Abstract Marcot, Bruce G. 1995. Owls of old forests of the world. Gen. Tech. Rep. PNWGTR-343. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific

Northwest Research Station. 64 p.

A review of literature on habitat associations of owls of the world revealed that about

83 species of owls among 18 genera are known or suspected to be closely associated with old forests. Old forest is defined as old-growth or undisturbed forests,

typically with dense canopies. The 83 owl species include 70 tropical and 13 temperate forms. Specific habitat associations have been studied for only 12 species

(7 tropical and 5 temperate), whereas about 71 species (63 tropical and 8 temperate)

remain mostly unstudied. Some 26 species (31 percent of all owls known or suspected to be associated with old forests in the tropics) are entirely or mostly restricted

to tropical islands. Threats to old-forest owls, particularly the island forms, include

conversion of old upland forests, use of pesticides, loss of riparian gallery forests,

and loss of trees with cavities for nests or roosts. Conservation of old-forest owls

should include (1) studies and inventories of habitat associations, particularly for

little-studied tropical and insular species; (2) protection of specific, existing temperate

and tropical old-forest tracts; and (3) studies to determine if reforestation and vegetation manipulation can restore or maintain habitat conditions. An appendix describes

vocalizations of all species of Strix and the related genus Ciccaba.

Keywords: Owls, old growth, old-growth forest, late-successional forests, spotted

owl, owl calls, owl conservation, tropical forests, literature review.
Summary To better understand the broader context of conservation strategies developed for

the Northern Spotted Owl in the Pacific Northwest of the United States, this paper

reviews the status and management of owls associated with old, closed-canopy, or

undisturbed temperate and tropical forests throughout the world.

A total of 83 extant owl species are associated with old forests. Twelve of these

species (seven tropical or subtropical and five temperate) are fairly well known to

be closely associated mostly with dense, old, or undisturbed forests. Examples

include Soumagne’s Owl of dense, evergreen rain forests of Madagascar; the Bay

Owl of Himalayan forests; the Northern Spotted Owl of the Pacific Northwest, and its

cousin the Himalayan Wood Owl of eastern Himalayas oak and conifer forests; and

the Crested Owl of dense forests of the Neotropics (figs. 22, 23). The remaining

71 species (63 tropical and 8 temperate) are associated with, and may be dependent

on, old forests but are essentially unstudied.

Basic inventories and ecological studies of habitat associations of many of these

83 species are needed. Priority should be given for species in isolated, insular, or

increasingly fragmented environments (for example, Celebes Barn Owl and Giant

Stops Owl) whose primary old-forest habitat is threatened and in decline, as it is

with many of the tropical species (for example, Scully’s Wood Owl and Fulvous

Owl; see figs. 12, 13).

Nearly a third of the 83 species occur on islands or peninsulas, and the remainder

are found in continental settings. The island forms are often at relatively higher risk

of population decline and extinction. At least six owl species recently extinct likely

were associated with old forests; five of these occurred on islands.

The greatest threat to owls of old forests is the direct loss of their habitats. One

example is the loss in recent decades of old, dense, interior forest habitat of wet

evergreen and moist deciduous forests in the Indo-Malayan area, which has caused

declines in populations of Brown Wood Owls and Bay Owls. Other threats, particularly to island forms, include conversion of older upland secondary forests, use of

pesticides, loss of riparian gallery forests, loss of trees with cavities for nests or

roosts, and tourism and other human disturbance.

No scientific studies have demonstrated to date that forestry can be used to restore

old-forest habitats and associated owl populations. In the Pacific Northwest, however,

silvicultural studies are underway to test how well old-forest components, such as

large live trees, large snags and down logs, and dense and diverse vegetation structures, can be maintained intentionally or induced by direct stand manipulation. One

phase of these studies involves testing behavioral and population responses by the

Northern Spotted Owl in National Forests. Restoration projects elsewhere, as in

Costa Rica and India, might help identify useful silvicultural methods to recover

local populations and habitats of old-forest owls, but much work still is needed.
Contents 1

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Introduction

Owls of Old Forests of the World

Owls of the Genus Tyto

Owls of the Genus Phodilus

Owls of the Genus Ofus

Owls of the Genus B&o

Owls of the Genus Srrix

Owls of the Genus Ciccaba

Other Little-Known Forest Owls

Implications for Old-Forest Management

Summary of Owls in Old Forests

Extinct and Endangered Owls of Old Forests

Old-Forest Owls in Continental and island Settings

Threats to Owls of Old Forests

Restoration of Old Forests

Nest Boxes Are Not a Long-Term Solution

Interpreting Habitat Associations

Forest Owls in Human Cultures

Acknowledgments

Measure Equivalencies

Literature Cited

Appendix A: The Songs of S&ix

Introduction

Origin and Purpose of Vocalizations

Vocalizations of Strix

Strix of the Nearctic Region

Sfrix of the Neotropical Region

Sirix of the Palearctic and Oriental Regions

Ciccaba: Tropical Cousins

Discussion

Literature Cited in Appendix A

Appendix B: Species and Selected Subspecies

Introduction The Northern Spotted Owl (Sfrix occidental/s caurina) has been the center of recent

controversies over conservation of ancient forests in the Pacific Northwest of the

United States. Globally, however, it is not the only owl species associated with oldforest habitats. This paper reviews species of owls associated with old temperate

and tropical forests throughout the world.

Although other authors (for example, Clark and others 1987) have summarized occurrence of some owl species by general forest types, none has done so for old

forests and with a global perspective. This report discusses owl species closely

associated with old, dense, or undisturbed forests, particularly species with populations or habitats declining in abundance or distribution. I generally follow taxonomies presented in Everett (1977) Clark and others (1978), Amadon and Bull

(1988), and Voous (1988). Scientific names of all old-forest owls are listed in table 1.

Scientific names of selected subspecies and species are included in the text for

clarity or for species not closely associated with old forests.

I do not discuss all species of owls found in forested habitats. I list species associated with dense, old-forest conditions in two categories: (1) species whose associations with such forests have been documented by primary scientific autecological

studies, and (2) those without studies but with anecdotal accounts suggesting close

association. I also denote species (1) whose ranges primarily occur in tropical latitudes (“tropical”) and (2) those mostly in temperate latitudes or in high-elevation

temperate forest habitats in tropical latitudes (“temperate”). As a point of comparison,

I also discuss some species that seem to inhabit other forest conditions successfully

and that can coexist in human-altered landscapes. I hope that this review will lead

to a broader understanding and better informed decisions on managing old-forest

habitats, such as those for the Northern Spotted Owl in the Western United States.

Owls of Old Forests It is not unusual for forest-dwelling wildlife species to exhibit specific affinities and

of the World adaptations for old- or undisturbed-forest environments. In many ways, much of the

wildlife of the world evolved in association with vegetation and environments unaltered

by human presence. This is also true with owls. Some owls have persisted in spite of

persecution by humans, such as the Great Horned Owl (Bubo virginianus), or have

successfully adapted to use of buildings and human habitations, such as the Barn

Owl (Tyto a/&). Others, including the Eurasian Eagle-Owl (Bubo b&o), have been

extirpated throughout much of their previous range (Clark 1987, Clark and others

1978, Fremming 1987; see fig. 26) but have persisted in areas of rather sparse

human presence. Such persistence indicates the extent to which some owl species

can tolerate additional habitat change. Many owl species have retained their close

affinities with the old forests in which they likely evolved (table 1) and have suffered

great declines because of habitat alteration.

Ecologies of most owl species are little known. Habitats, particularly of forest owl

species, seldom are described in details of forest age, structure, flora, or degree of

disturbance. Thus, in this report, “old forest” refers to various conditions, particularly

(1) closed-canopy forests (which often denotes undisturbed, mature or old-growth

forests); and (2) forested stands and landscapes little disturbed by human activities,

especially timber harvests, human settlements, agriculture, and human-caused fires.

1
Table l-Owls primarily associated with old tropical or temperate forest@

Species Tropica? Temperateb Range, habitat

Tyfo, Barn Owls and relatives:

Celebes Barn Owl (T. rosenbergi/)

Sooty Owl (7: tenebricosa)-

Lesser Sooty Owl (T. multipun&@ (recently listed

as separate species)

Soumagne’s Owl (T: soumagneo

Sula Island Barn Owl (7- nigrobrunnea)

Minahassa Barn Owl (7: inexspectata)

T. pollens (extinct)

Phodilus, Bay Owls:

Bay Owl (f? badius)

Prigogine’s Owl or African bay owl (I? prigoginel)

Ofus, stops Owls:

Spotted Stops Owl (0. spilocephaluscspilocephalus)-

Javan Stops Owl (0. s. angelinae)

White-Fronted Stops Owl (0. sagittatus)

Reddish Stops Owl (0. rufescens)

Giant Stops Owl (0. gurney4 (sometimes Mirnizuku

gurney4

Tawny-Bellied Screech Owl (0. watsonil)

Puerto Rican Screech Owl (0. nudioes)

Flores Stops Owl (0. alfred/) ’ ’

Rajahs Stops Owl (0. brooki/)

Lesser Sunda Stops Owl (0. silvicolus)

Sandy Stops Owl (0. icterorhynchus)

Sokoke Stops Owl (0. ireneae)

Mentaur Stops Owl (0. umbra)

Cuban Screech Owl (0. lawrenci!)

Santa Barbara or Bearded Screech Owl (0. barbarus)

Black-Capped Screech Owl (0. atricapillus)

Rufescent Screech Owl (0. ingens)

Cinnamon Screech Owl (0. pefersonl)

Cloud-Forest Screech Owl (0. marshal//)

Colombian Screech Owl (0. colombianus)

Bare-Shanked Screech Owl (0. clarkii)

White-Throated Screech Owl (0. albogularis)

Roborate Screech Owl (0. roboratus)

Seychelles Stops Owl (0. insularis)

Sao Theme Stops Owl (0. hartiaubi)

Lan Yu Stops Owl (0. elegans botelensis)

Pacific Screech Owl (0. cooper0

Anjouan Island Stops Owl (0. rufilus capnodes) (recently

extinct)

Mauritius Stops Owl (0. commersom) (recently extinct)

Bubo, Eagle-Owls:

Forest Eagle-Owl (EL nipalensis)

Shelley’s Eagle-Owl (5. shelleyo

Akun Eagle-Owl (f3. leucostictus)

Fraser’s Eagle-Owl (EL poensis)

Barred or Malay Eagle-Owl (f3. sumafranus)

Milky or Verreaux’s Eagle-Owl (5. lacfeus)

Philippine Eagle-Owl (El. philippensis)

Nduk Eagle-Owl (5. vosselen)

Leguat’s Owl (5. leguafi) (recently extinct)

?

?

?

X

?

;7)

X

?

?

?

?

?

?

?

?

?

?

?

?

?

?

?

?

?

?

?

?

?

?

?

?

;,

(?)

X

?

?

?

?

?

?

[?)

Celebes rain forest

Australia

Northeast Queensland

Madagascar dense evergreen rain forest

Indonesia

Indonesia

Bahamas pine barrens

Himalayas dense evergreen forest

Congo montane forest

? Southeast Asia evergreen forest

Java mountain forests

Malaysia lowland and foothill forest

Southeast Asia dense low-elevation forest

Philippines lowland rain forest

Amazonia rain forest

Puerto Rico

Lesser Sundas mountain woods

Sumatra

Lesser Sundas coastal forest

African Gold Coast forest

East Kenya coastal forest

Southwest Pacific coastal forest

Cuba forest

Mexico

South America subtropical rain forest

South America subtropical forest

Peru and Ecuador high-cloud forest

Peru high-elevation cloud forest

Colombia high-elevation mountain forest

Central America highland forest

? Northern Andes highland cloud forest

? Peru Andes highland forest

Mahe in Seychelles

Sao Theme island

Taiwan forests

Neotropics deciduous and evergreen forest

Anjouan Island forests?

Mauritius Island forests?

India Himalayas dense submontane forest

Africa tropical and subtropical forest

Africa tropical and subtropical forest

Africa tropical and subtropical forest

Greater Sundas forests

Sub-Sahara Africa dense riverine forest

Philippine Islands tropical rain forest

Tanzania Usambara Mountain forests

Leguat forests
Table l-Owls primarily associated with old tropical or temperate forest@ (continued)

Species Tropicalb Temperateb Range, habitat

Sfrix, Wood Owls:

Northern Spotted Owl (S. occident&s caurina)

California Spotted Owl (S. occidentalis occidentalis)

Himalayan Wood Owl (S. aluco nivkola)

Scully’s Wood Owl (S. aluco biddulphfl

Brown Wood Owl (S. leptogrammica)

Fulvous Owl (S. fulvescens)

Malay Wood Owl (S. orientalis).

Spotted Wood Owl (S. seloputo)

Rufous-Legged Owl (S. rufipes)

Rusty-Backed Owl (S. hylophila)

Mauritius Owl (S. sauzierfl (recently extinct)

Ciccaba, Mottled Owls:

Black-and-White Owl (C. nigrolineata)

Black-Banded Owl (C. huhula)

Rufous-Banded Owl (C. albitarsis)

African Wood Owl (C. woodfordii sokokensis)

Crested Owls and relatives (Lophostrix spp.):

Crested Owl (L. cristata)

Maned Owl or Akun Stops Owl (L. /etti/) (sometimes

Jubula leftid

Fish Owls (Ketupa spp.):

Blakiston’s Fish Owl (K. blakistonl)

Tawny Fish Owl (K. flavipes)

Fishing Owls (Scotopelia spp.):

Pel’s Fishing Owl (S. pe/Q

Rufous Fishing Owl (S. us&en)

Vermiculated Fishing Owl (S. bouvien)

Spectacled Owl and relatives (Pulsatrix spp.):

Spectacled Owl (I? perspicillafa)

White-Chinned or Tawny-Browed Owl

(P. koeniswaldiana)

Rusty-Barred or Band-Bellied Owl (P. melanota)

Pygmy-Owls (Glaucidium spp.):

Red-Chested Owlet (G. tephronotum)

Chestnut-Backed Owlet (G. sjostedtl)

Andean Pygmy-Owl (G. jardin@

Albertine Owlet (G. albertinum)

Cuckoo Owl (G. cuculoides)

Eared Owls (Asio spp.):

Abyssinian Long-Eared Owl (A. abyssinicus)

Madagascar Long-Eared Owl (A. madagascariensis)

Long-Whiskered Owlet (Xenoglaux lowery!)

Papuan Hawk Owl (Uroglaux dimorpha)

X

?

?

?

?

;,

X

?

?

X

?

?

?

?

?

?

?

?

?

?

X Western North America old-growth conifers

X California mixed- and old-growth conifers

X Eastern Himalayas oak and conifer forest

? Kashmir

?

X

?

?

?

Indo-Malaysia hill and submontane jungles

Neotropics cloud and mountain forest

Malaysia forests

Malaysia forests

South America dense tropical forest

South America dense tropical forest

Mauritius forests?

Neotropics lowland evergreen forest

Amazon Basin lowland tropical forest

Andes humid temperate forest

Sub-Sahara Africa lowland and mountain

forest

Neotropical dense forest

West Africa tropical forest

Southeast Asia riverine forest

Southeast Asia riverine forest

Africa gallery and tropical rain forest

Africa gallery and tropical rain forest

Africa gallery and tropical rain forest

Neotropical lowland forest

Neotropical lowland forest

Neotropical lowland forest

West Africa rain forest

West central Africa lowland rain forest

Andes wet dense montane forest

Zaire

Himalayan forests

East Africa

Eastern Madagascar humid forests

Peru Andes upper subtropical cloud forest

New Guinea

3
Table l-Owls primarily associated with old tropical or temperate forestsa (continued)

Species Tropicalb Temperateb Range, habitat

Hawk Owls (Ninox spp.):

Rufous Owl (N. rufa)

Ochre-Bellied Hawk Owl (A/. perversa)

Andaman Hawk Owl (N. arrinis)

Philippine Hawk Owl (IV. philippensis)

Indonesian Hawk Owl (N. squamipila)

Brown Owl (N. theomacha)

Fearful Owl (Nesasio solomonensis)

Tengmalm’s or Boreal Owl (Aegolius funereus)

Forest Spotted Owlet (Athene blewif@ (recently extinct?)

Total living species, (x) known to be primarily associated

with old forests (12 total)

(?) suspected to be primarily associated with old forests

(71 total):

Total (83 spp.($

??I

7

6 3

7 0

Australia

Celebes deep virgin forests

East Indies forests

Philippines forests

Southeast Asian island forests

New Guinea lowland rain forest

Solomon Island lowland primary forest

Holoarctic conifer forest

Central India deciduous forest

5

8

13e

a Many additional owl species are not listed here that also occur in old forests but not necessarily as primarily selected habitat. See text for

gitations.

x = primarily associated with old forests; ? = reportedly associated with old forests, but little is known of their ecology; (?) = recently extinct.

: Considered as a separate species, Javan Stops Owl (Ofus angelineae), by Hume and Boyer (1991) and Amadon and Brown (1988).

Includes listing of 2 subspecies of Ofus spilocephalus under both tropical and temperate categories but only one listing of Srrix occidentalis

under temperate category.

e Includes listing of 2 subspecies of Sfrix aluco under both known and suspected categories,

In this report, I discuss the various old forests in which owls are found, the threats to

the survival of forest habitats and owl populations, the need to conserve and restore

owl populations and their old-forest habitats, and the roles owls have played in

human cultures. All these topics need to be studied and considered in conservation

plans if we are to provide successfully for continued existence of owls associated

with old forests of the world.

Owls of the Genus Tyto Most species of Tyto, including the Barn Owl, inhabit grassy or open habitats. A few

little-known species, however, occupy deeply forested environments.

Celebes Barn Owl-This species inhabits rain forests of Celebes (Everett 1977).

Hume and Boyer (1991) noted that it occurs in rain forests of several of the Sulawesi

(Celebes) islands but that it also is associated with lowland habitats now eroded by

deforestation. Little is known of its ecology.

Sooty Owl and Lesser Sooty Owl-Another little-studied Tyto, the Sooty Owl

occupies dense forests of eastern Australia and New Guinea (Clark and others 1978,

Everett 1977, Pizzey 1980, Prestt and Wagstaffe 1973; also see fig. 59). Like the

Celebes Barn Owl, its ecology is also little known. Cayley (1975) noted that the

Sooty Owl occurs as isolated pairs in heavy mountain forests. Pizzey (1980:205)

denoted habitat of the Sooty Owl as “dense tropical, subtropical and temperate

rain-forests and fern-gullies.”
Old Conifer Forests of North America

1. Ancient forest of western hemlock

(Tsuga heterophylla) and western redcedar (T/X& plicafa), Olympic National

Park, western Olympic Peninsula,

Washington. Such stands are habitat

for the Northern Spotted Owl (Strix

occident& caurina) but in recent years

also have been invaded by the Barred

Owl (Sfrix varia). The Barred Owl is fast

becoming coexistent with, and in many

cases replacing, the less aggressive

Spotted Owl.

2. Fragmentation of western hemlock

forests in southeast Alaska, Tongass

National Forest, from timber harvesting

(clearcutting). Such harvesting locally

opens forest canopies and eliminates

habitat for Boreal (Tengmalm’s) Owls

(Aegolius funereus) and other species.

3. Selective cutting of western hemlock

forests in southeast Alaska. If such

cutting does not greatly reduce canopy

closure or nesting substrate (including

snags and cavity-bearing trees), then it

may be compatible with conserving

habitat for some of the old-forest owl

species. Studies are needed, however,

to assess the response of each species.

Hume and Boyer (1991) and Amadon and Bull (1988) list the Lesser Sooty Owl,

previously considered a subspecies of the Sooty Owl, as a separate species. Hume

and Boyer note that both species inhabit patches of rain forest and wet eucalyptus

forests containing old trees with hollow trunks suitable for nesting and roosting, and

that the Lesser Sooty Owl favors extensive tracts of rain forests. Both owls have

recently taken to roadsides and clearings as foraging habitat, however.

5
Soumagne’s Owl-Soumagne’s Owl is found only in large, dense, evergreen forests

of northeastern Madagascar. It has been sighted only in 1929 and 1973 (Clark and

others 1978). Its precise habitat requirements are unknown. Hume and Boyer (1991)

called this species Madagascar Grass Owl. They suggest that the loss of forest cover

on Madagascar and the conversion of forests to plantations of introduced eucalyptus

and other trees unsuitable for this species have contributed to its decline and present

scarcity.

Owls of the Genus The genus Phodilus shares the family Tytonidae with the well-known Barn Owl and

Phodilus Grass Owls. Although the Barn Owl is known for-indeed, even named for-its

tolerance and affinities for human-built structures and habitations, Phodilus is less

well known and is associated only with deep forests of Indonesia. A second species

recently has been discovered in Africa.

Bay Owl-The seldom-seen Bay Owl is small with short ear tufts, fully feathered

legs, a compressed bill, and rather short wings for hunting in deep forests of the

Himalayas (figs. 55, 56). Natural history of Bay Owls is little known (Marshall 1966).

Ali (1962) noted that one subspecies, the Sikkim Bay Owl (P. bad/us saturafus), is

a rare resident of dense foothill forests in Himalayan valleys of Nepal and Sikkim,

India (fig. 35). It is confined to dense evergreen forest in the submontane tracts and

foothills locally up to about 1500 m (Ali and Ripley 1983). King and others (1975)

note habitat associations of this subspecies as forest and second growth. They

define “second growth” as new plants growing where the original plants have been

removed, as in the rank growth following deforestation. All other sources, however,

describe habitat of Bay Owls as dense, old, and undisturbed forests.

Little is known of Sikkim Bay Owls. Ali and Ripley (1983) provide the following

descriptions. Sikkim Bay Owls are strictly nocturnal and seldom seen. In daytime

they roost in cavities and hollows in tree trunks. The nest is in an unlined hollow

in a tree trunk or rotten stump about 2 to 5 m high. The same nest site is used

every year and is littered with casts and pellets. At night, Sikkim Bay Owls hunt by

launching from perches to fly through dense understory stands of young trees after

its prey of small mammals, birds, lizards, frogs, and beetles and other large insects.

The Burmese subspecies P. 6. bad& occurs in evergreen and pine forests and

feeds chiefly on mammals and birds. It frequents pools and riparian areas along

rivers and also takes some fish. In higher elevations, it is confined to evergreen

forests (Smythies 1984). The Ceylon subspecies (P. b. assimilis), endemic to Sri

Lanka, is a little-known, scarce resident of forests below 1200 m in both the wet

and hill zones (Ali and Ripley 1983). The Peninsular Bay Owl (P. 6. ripley/), a rare

resident of central and southern India, occurs in dense wet evergreen forests (Ali

and Ripley 1983; also see fig. 38).

Prigogine’s Owl or African Bay Owl-Everett (1977) and Clark and others (1978)

briefly note the discovery of Prigogine’s Owl, a single specimen of which was discovered in 1951 northwest of Lake Tanganyika of the eastern Congo. It seems to

inhabit montane forests (fig. 29)-Hume and Boyer (1991) speculate that it survives

inside the threatened forests of Zaire-but essentially is unknown.
Old Hardwood Forests of North America

4. Emory oak woodland (Quercus

emorv,) at Madera Canyon, southern

Arizona. The upland forests here also

contain silverleaf oak (0. hypoleucoides),

Arizona sycamore (Plantanus wrighti/),

alligator juniper (Juniperus deppeana),

and Chihuahua pine (Pinus leiophylla

var. cbihuahuana); and Fremont

cottonwood (Populus fremonfil) along

riparian areas. Flammulated Owls

(Qfus Nammeolus), as well as Western

Screech-owls (0. kennicotfii), Whiskered

Owls (0. trichopsis), and Mexican

Spotted Owls (S&ix occidentalis lucida),

inhabit the canyon forests.

5. Blue oak woodland (Quercus

douglash) along the interior foothills

to the Sierra Nevada mountains,

Central Valley, California. Such

woodlands are used by some

individual Caiifornia Spotted Owls

(Strix occidentalis occidentalis) which

migrate seasonally from higher mixedconifer forests. Blue oak woodlands

often also contain digger pine (Pinus

sabiniana) and are threatened with

removal from increasing urban

construction.

Owls of the Genus Otus Taxonomy of Otus species, particularly of the Neotropics, Middle East, and Southeast Asia, is somewhat uncertain. Clark and others (1978) list 32 species, Everett

(1977) lists 34, Hume and Boyer (1991) list 41, and Marshall and King (1988) list 52,

worldwide.

Following are descriptions of eight species of 0fu.s facultatively associated with old

forests, although a few subspecies seem to be obligate associates. Lesser known,

more habitat-specific old-forest obligates are then listed beyond.

Mountain Stops Owl (0. spilocephalus)-Found throughout the mountains of

Southeast Asia, the Mountain Stops Owl inhabits various evergreen forest types.

These types include oak, rhododendron, pine, and deodar forests of the Himalayas

at 600 to 2700 m (de Schauensee 1984); and both cool, evergreen, broad-leaved

and mossy elfin forests of the Sumatra and Borneo highlands (Voous 1988). King

and others (1975) note that the species occurs in both evergreen and second-growth

forests.

One subspecies of the Mountain Stops Owl, the Spotted Stops Owl, is found up to

2600 m (Ali 1977) and is confined to hill-oak, pine, and deodar forests (Ali 1949; also

see fig. 38). Its daytime perch is in tree cavities (Ali 1977). Nests in the Himalayas

have been found in abandoned woodpecker or barbet cavities (Voous 1988). Another

subspecies, the Javan race 0. s. angel&e, occurs in mountain rain forests and is

considered by some as a separate species (Amadon and Bull 1988, Hume and

Boyer 1991).

7
Oriental Stops Owl (0. sun&)-The Oriental Stops Owl 0. s. stecfinatfus is

probably the Old World ancestor of the Flammulated Owl.’ In Southeast Asia, the

Oriental Stops Owl occurs in tropical evergreen and deciduous forests in lowlands

and hills, up to 2300 m in oak and pine forests in the Himalayan foothills (Roberts

and King 1986). In Myanmar (Burma), this species also is found in hill cultivations,

gardens of rural villages, and teak forests (Voous 1988). Although it probably is not

dependent on old, undisturbed forest habitats, it is found in open or primeval deciduous and mixed-riparian forests (Knystautas and Sibnev 1987, Pukinsky 1977) and

in broad-leaved forests up to 1500 m in Honshu, Japan (Voous 1988).

Daytime roosts are high in a tree in dense foliage. It feeds in glades and along forest

edges and in open, parklike woods, taking prey from the forest floor as well as from

the tree canopy and has been observed nesting in the big sacred trees surrounding

temples and shrines (Voous 1988).

Collared Stops Owl (0. bakkamoena)-This Indo-Malayan species is found in

tropical rain forests, tropical winter-dry forests, Savannah, temperate, and marginally

boreal climatic zones. It inhabits evergreen and deciduous tropical and subtropical,

humid and arid forests, as well as forest edges and wooded areas near cultivations

and villages (Ali 1977, 1979; Hume and Boyer 1991; Voous 1988). Collared Stops

Owls are found in dipterocarp, oak, pine, and deodar forests in the Himalayan foothills up to 2400 m (Ali 1977, Ali and Ripley 1969); in subtropical and temperate

mixed-deciduous forests in China (Voous 1988); in primeval broad-leaved forests

with elms, ashes, and grassy openings in the Russian Far East (Knystautas and

Sibnev 1987, Nechaev 1971); and in river valleys and hills near edges of coniferous

taiga of birch and poplar in Siberia (Voous 1988). Although the species is associated

with many forest types, some of them old growth, it also has acclimated to nest

boxes and human-altered landscapes (Voous 1988).

Flammulated Owl (0. flammeo/us)-This western North American species inhabits

a diversity of conifer and mixed-conifer-hardwood forest types (for example, fig. 4),

including pine, Douglas-fir, and true firs (Bull and others 1990, Goggans 1986,

Marcot and Hill 1980, Reynolds and Linkhart 1987), with affinities to mature and

old-growth forests (Howle and Ritcey 1987, Reynolds and Linkhart 1987). The

species, however, does not seem to be an obligate associate of old-growth forests.

Nests are typically in abandonded woodpecker cavities in dead trees and less

commonly in natural cavities of dead or live trees, including oaks (for example,

Marcot and Hill 1980). The diet consists of arthropods and lepidopterans. Reynolds

and Linkhart (1987) report that the affinity of Flammulated Owls for old yellow pine

forests in Colorado is because such forests afford nest cavities, adequate stand

structure for roosts, and availability of arthropod prey. In Colorado, where on rare

occasions Flammulated Owls will nest in pinyon-juniper woodland, the diet includes

moths (see footnote 1).

’ Personal communication. Jon Winter, 5331 El Mercado

Parkway, Santa Rosa, CA 95401.
Vermiculated Screech Owl (0. guatema/ae)-This species is found in Central

America and western South America in dense, tall, and continuous broad-leaved

forests, from tropical deciduous and thorn forests in lowlands and foothills up into

oak woodland; and also in evergreen upper elevation tropical rain forests in southern Mexico (Marshall 1967, 1978; Peterson and Chalif 1973; Voous 1988; also see

fig. 11). Clark and others (1978) note that it is found in open forests and plantations.

Hilty and Brown (1986) list its habitat as understory to lower midlevels of humid

forest and second-growth forests in lower elevations. It also inhabits temperate oak

woodlands of Mexico and tropical cloud forests of Central and South America (Stiles

and Skutch 1989, Voous 1988; see fig. 19). The Vermiculated Screech Owl is a

facultative but not obligate inhabitant of older native forests.

Other species of Otus facultatively associated with old forests include the Western

Screech Owl (0. kennicoffl), Eastern Screech Owl (0. asio), and Whiskered Screech

Owl (0. trichopsis) (see Marshall 1967, 1978). Each of these species is found in

North America in various conifer, mixed-conifer and hardwood, and pure hardwood

forests, at times near human habitations (for example, see fig 4). Each is found not

only in old undisturbed forests but also in various other types of broken woodlands

(personal observation) and sometimes in nonwooded areas, in the case of the

Western Screech Owl.’

A listing of other, little-studied Otus species of dense tropical forests (Clark and others

1978, Everett 1977, Hilty and Brown 1986, Hume and Boyer 1991, King and others

1975) is formidable (table 1):

.

.

.

.

.

.

.

.

.

.

White-Fronted Stops Owl, occurring in Malaysian lowland and foothill forests

The rare Reddish Stops Owl of Southeast Asian dense lowland and hill forests

(Hekstra 1973)

Giant Stops Owl, sometimes placed in the monospecific Mimizuku (Amadon and

Brown 1988, Clark and others 1978, Hume and Boyer 1991), endemic to lowland

rain forests of the Philippines

Tawny-Bellied Screech Owl of Amazonian rain forests (fig. 17)

The endangered Puerto Rican Screech Owl of submontane woodland and tropical

forests of Puerto Rico and Virgin Islands (see figs. 6-10)

Flores Stops Owl of mountain woods in the Flores Islands of the Lesser Sundas

Rajah’s Stops Owl of lowland forests of Sumatra and Borneo

Lesser Sunda Stops Owl of coastal forests in Flores and Sumbawa Islands of

the Lesser Sundas, although Hume and Boyer (1991) note that it lives close to

human settlements and seems adaptable to several habitats

Sandy Stops Owl of forests of the African Gold Coast from Ghana to East Congo

Sokoke Stops Owl of coastal forests of East Kenya, Africa

’ Personal communication. Carl Marti, Department of

Zoology, Weber State College, Ogden, UT 84408.

9
.

l

.

.

.

l

.

.

.

.

.

.

l

Mentaur Stops Owl, found in coastal forests of the Simaur and Engano Islands

of the southwest Pacific

Cuban Screech Owl, sometimes placed in the monotypic genus Gymnoglaux,

which inhabits forests of limestone country of Cuba (see figs. 6-9)

Santa Barbara or Bearded Screech Owl, found in mountain woodlands from

1350 to 1850 m in Mexico and Guatemala (fig. 11)

Black-Capped Screech Owl of subtropical rain forests in eastern South America,

including Paraguay, southeast Brazil, and northeast Argentina

Rufescent Screech Owl, found in subtropical humid cloud forests of western

South America from Bolivia to Venezuela (figs. 18, 19)

Three closely related species listed by Hume and Boyer (1991): Cinnamon

Screech Owl of Peruvian and Ecuadorian high-elevation cloud forests, CloudForest Screech Owl of high cloud forests of Peru (figs. 50, 51), and Colombian

Screech Owl of Colombian high-elevation mountain forests (figs. 18, 19)

Bare-shanked Screech Owl of highland forests from 1300 to 2330 m in Costa

Rica and Panama (fig. 15; although Hilty and Brown 1986 list habitat as including

forest, woodland borders, and tree-lined fence rows)

White-Throated Screech Owl of subtropical to temperate forests in the Andes

and other mountains above 2100 m, found in western South America from

Venezuela to Bolivia (fig. 18; although Hilty and Brown 1986 also list highland

forest borders, open woodland, and semiopen areas with scattered trees as

habitat for this species)

Roborate Screech Owl, found in Andean forests at about 3000 m in western

Peru (fig. 18), although Hume and Boyer (1991) list its habitat as scrub and

high open woodland

Seychelles Stops Owl, rare in remote, high valley cloud forests, but possibly

increasing as secondary forests mature; once considered an island race of the

Madagascar Stops Owl (Hume and Boyer 1991)

Sao Theme Stops Owl, found in forests on S&o Theme island off western Africa

and possibly a well-marked race of the common Stops Owl (Hume and Boyer

1991)

Lan Yu Stops Owl of Taiwan forests

Pacific Screech Owl, which frequents deciduous and evergreen forests of the

Neotropics (Marshall 1967; personal observation; fig. 17), although Hume and

Boyer (1991) list its habitat as low scrub and coastal mangrove. Solis and

Manley3 report the species in a building compound in a private reserve of

primary dry tropical forest in northwestern Costa Rica.

3 Personal communication. David Solis and Patricia Manley,

USDA Forest Service, Pacific Southwest Regional Office,

Fish and Wildlife Unit, 630 Sansome Street, San Francisco,

CA 94111.

IO
Owls of the Genus Bubo Members of Bubo include some of the most aggresive hunters in the owl world. The

following species seem to associate primarily with old or dense forests.

Forest Eagle-Owl-The Forest Eagle-Owl is well named, as it is a fierce hunter of

primarily densely forested areas. Habitat of several subspecies closely associated

with old forests have been described as follows.

The rare Forest Eagle-Owl B. nipalensis nipalensis occurs in dense tropical forests

of Sikkim, India, up to about 2100 m, more normally to about 900 to 1200 m (Ali

1962, Ali and Ripley 1983; also see fig. 35). It frequents submontane forest tracts

of the lower Himalayas, occurring in dense evergreen and moist deciduous forests

in tropical valleys, terai and duars (wet perennial grasslands along the Himalayan

foothills), and sholas (dense riparian gallery forests) (Ali 1977, Ali and Ripley 1983).

Mostly nocturnal, the Forest Eagle-Owl roosts diurnally on densely foliaged tree

boughs in deep forests or sholas (Ali 1949) and occasionally hunts during the daytime. At dusk, it moves to the edge of clearings and streams but “is essentially a

forest dweller and does most of its hunting within the forest” (Ali and Ripley

1983:248). Its nest typically consists of “a hollow in an ancient tree or a deserted

stick-nest of an eagle” (Ali and Ripley 1983:248), although it also lays eggs on bare

soil in a cave or in a fissure on a rock scarp (Ali 1949, Ali and Ripley 1983).

Smythies (1984) reports that Huhua nipalensis (= B&o nipalensis) frequents forests

and their outskirts in the Himalayas of Myanmar. In Sri Lanka, the endemic Ceylon

Forest Eagle-Owl (f3. n. b/igh/) also inhabits deep tropical forests (Ali and Ripley

1983). The only reported nest was a “collection of debris in the hollow formed by the

junction of large boughs” about 6 m high in a big tree by a stream in dense forest at

about 600 m (Ali and Ripley 1983:249).

Other, less well-known species of Bubo associated with old or dense, mostly tropical

forests (Clark and others 1978, Everett 1977, Fogden 1973, Hume and Boyer 1991,

King and others 1975, Voous 1988), include the following:

. Shelley’s Eagle-Owl, Akun Eagle-Owl, and Fraser’s Eagle-Owl of African tropical

and subtropical forests (fig. 28)

l Barred or Malay Eagle-Owl of mountain rain forests in the Greater Sundas

. Milky or Verreaux’s Eagle-Owl of dense riverine forests of sub-Sahara Africa

(Newman 1991; also see figs. 30, 31) although Hume and Boyer (1991)

describe its habitat as including dry woodland, introduced conifers and

eucalyptus, and brushveld

l Philippine Eagle-Owl of tropical rain forests of the Philippine Islands

11
Owls of the Genus Strix Commonly referred to as “wood owls,” species of the genus Strix are found throughout the Northern Hemisphere. Wood owls occur mostly in temperate to subboreal

forests, although a few specialists are found in subtropical to tropical environments.

Extant members of Strix likely are derived from a more circumpolar stock that was

north temperate or subboreal, some offshoots of which radiated into narrower geographic areas and evolved close affinities with specific climatic environments and

vegetation conditions. Examples of such radiations include the split of Tawny Owl

and Ural Owl in Europe and Asia and the Barred Owl and Spotted Owl in North

America. Of these two pairs, the Tawny and Barred Owls attained a more southerly

distribution and evolved a greater tolerance to disturbed temperate forests and to a

wider range of vegetation conditions and climates than did their Ural and Spotted

Owl counterparts.

The wood owls, true to their namesake, are strongly affiliated with and adapted to

forest habitats. There they find cover, prey, and nesting substrates to meet their

life needs. Their brownish cryptic coloration, broad wing shape, and maneuverable

manner of flight and foraging all suggest life within wooded environments. Despite

their worldwide distribution, members , of the genus Strixand the related

subtropical and tropical genus Ciccaba

(see below) have many common

Old Forest Species of Sfrix

vocalization patterns (see appendix A).

Northern Spotted Owl S. occidentalis caurina

Himalavan Wood Owl S. &co nivicola

Spotted Owl-A denizen of western Scully’; Wood Owl S. aluco biddulphi

North America, the Northern Spotted Brown Wood Owl S. leptogrammica

Owl (S. occidentalis caurina) is known Fulvous Owl S. fulvescens

to consistently select old-growth and Malay Wood Owl S. orientalis

mature stands of conifer forests Spotted Wood Owl S. seloputo

(appendix F in Thomas and others

Rufous-Legged Owl S. Wipes

1990; also see fig. 1, this report).

Rusty-Backed Owl S. hylophia

Northern Spotted Owls typically nest

in large cavities in trees and less often on mistletoe clumps and abandoned raptor

nests in the understory of tree canopies (Forsman 1980). Day roosts of this mostly

nocturnal species are in older forest stands with dense overhead foliage and diverse

understory vegetation (Thomas and others 1990).

The California Spotted Owl (S. o. occidentalis) is found throughout Sierran forests of

mixed-age and mixed-species composition (also see fig. 5), but Verner and others’

(1992:9) analysis demonstrated that it selects very large, old trees for nest sites and

forests having medium-sized and larger trees and high canopy closure. Thus, it can

be considered here as closely associated with old-forest conditions. The Mexican

race (S. o. lucida) of the Southwest United States and northwest Mexico is found in

copses of hardwoods, along forested washes, and in more extensive mixed forests

of pine, perhaps representing an ecotype of the species locally adapted to shady,

moist microhabitats (fig. 4).

Because of rising polemics over conflicting use of its old-growth habitat, the Spotted

Owl is probably one of the best known species of owls in the Western United States.

In recent years, dozens of scientists and several hundred biologists have been engaged in research, inventory, and monitoring studies of the species in young and old

forests on private and public lands.

12
Old Forests of the Caribbean

6. Old-growth forest of Caribbean pine (Pinus

caribbeanensis), central Andros Island, Bahamas.

These forests probably once held the meter-tall,

flightless Tflo pollens. Similar forests on Cuba

still provide habitat for the rare Cuban Screech

Owl (Otus lawrencii). 7. Much of the old tropical forest of

the Caribbean has been converted

to second-growth scrub and human

habitations. Here, the old Caribbean

pine forests of the Bahamas have been

cleared for industrial agriculture. Similar

conversions have occurred in the tropics

worldwide, reducing available habitat to

many island-dwelling species of

old-forest owls.

8. Most of the old-growth Caribbean pine forests of Andros

Island, Bahamas, had been harvested and converted to crop

fields or, as shown here, second-growth pine plantations.

The plantations are cut by individual tree or small group

selection and provide forest cover. It is unknown, however,

if such silvicultural methods would suffice to retain habitat

for Cuban Screech Owls on Cuba or other old-forest owls

of the Caribbean and the Greater and Lesser Antilles.

9. The original old forests of the shores of the Caribbean

islands (above) have been largely invaded by introduced

species such as Australian pine (Casuarina equisetifolia),

reducing or eliminating habitat for owls more closely

associated with native pines and hardwoods.

10. Dense, tropical second-growth scrub of St. John,

U.S. Virgin Islands (left). The old tropical forests were

eradicated mostly during the latter half of the 19th century

when sugar mills dominated the Lesser Antilles. The

Puerto Rican Screech Owl (Otus nudipes) has become a

scarce inhabitant found only on Puerto Rico and the Virgin

Islands, its habitat greatly reduced from felling of the old

tropical forests.

13
Barred Owl (S. var@-The Barred Owl occurs throughout North America in various

forest ages, types, and conditions, ranging from dense Douglas-fir forests of the

Pacific Northwest to lowland basswood groves and isolated hammocks of mahogany

and broad-leaved hardwoods of southern Florida (personal observation). The species

is not an old-forest obligate. Its recent movement into the Pacific Northwest of North

America (Taylor and Forsman 1976) including into both young, managed forests and

extensive tracts of old-growth conifer forests, has led, however, to direct territorial

conflict with the Spotted Owl (Hamer 1985, Johnson 1992). It apparently has recently

moved west across British Columbia, south into the Pacific Northwest, and now into

California. This movement might have resulted from widespread logging of old forests

over the second half of the 20th century, as such activities often remove large snags

and live trees with hollows affording nest sites (Bosakowski and others 1987). This

hypothesis is untested, however.

In a few cases, Barred Owls have hybridized with Northern Spotted Owls and

even produced apparently fertile offspring.4 This is not suprising, however, as many

closely related species of birds have been observed to hybridize (Ehrlich and others

1988:501ff), including the Tawny and Ural Owls in Europe (Scherzinger 1983). To

date, observations of interactions and interbreeding between Barred and Spotted

Owls definitively indicate neither long-term genetic swamping of either species

(particularly the threatened Spotted Owl) nor competitive exclusion of entire Spotted

Owl populations by the Barred Owl. The outcome of the Barred Owl’s range extensions on long-term viability of Spotted Owl populations has yet to be determined and

deserves further study.

Great Gray Owl (S. nebu/osa)-The circumpolar Great Gray Owl is found in old

mature subalpine forests of spruce, fir, and pine; mixed-hardwood forests in east

Asia; and taiga and boreal muskegs and bogs (Hilden and Solonen 1987, Hume and

Boyle 1991, Spreyer 1987, Voous 1988; see figs. 2, 3). It also is found in fairly open

subboreal forests of North America.5 In Sweden, it inhabits northern conifer forests

and is tied closely to vole cycles (Mikkola 1983). In winter, it ventures into agricultural

fields and along forest edges and openings for foraging on small rodents, sometimes

close to human habitations (but see fig. 26). Although found in mature subboreal

forests, the Great Gray Owl probably is not an old-forest obligate per se. In fact, in

northeastern Oregon, it reached greatest nonbreeding densities in heavily logged

areas (Bull and Henjum 1990, Bull and others 1988). De Schauensee (1984) however, notes its habitat in China as dense coniferous forests, and Hume and Boyle

(1991) wrote that in Europe and Asia it occupies mature, lichen-covered spruce, fir,

and pine, often mixed with larch and poplar, and sometimes birch woodlands.

4 Personal communication. Eric Forsman, USDA Forest

Service, Forestry Sciences Laboratory, 3200 SW Jefferson

Way, Corvallis, OR 97331.

5 Personal communication. Evelyn Bull, USDA Forest

Service, Forestry and Range Sciences Laboratory,

1401 Gekeler Lane, La Grande, OR 97850.

1 4
Great Gray Owls nest mostly in abandoned raptor nests, particularly those of

Northern Goshawks (Accipitergentilis), and also in mistletoe platforms in eastern

Oregon (Bull and others 1987). They do not use tree cavities, but in Idaho and

California, this species nests in the tops of broken-off snags in areas where raptor

nests are scarce (Winter 1986; see endnote 5). Their use of raptor nests and

mistletoe clumps accounts for their presence in boreal forests that otherwise lack

snags of adequate size and number.

Tawny Owl (S. &co)-The well-studied Tawny Owl is found widespread throughout

mixed woodlands, especially deciduous forests (Perrins 1987), of Europe and Asia

(Mikkola 1987). It normally nests in tree cavities. In Europe, it has acclimated to the

use of nest boxes and occurs in various forest conditions, including old dense forest,

upland spruce forests (Petty 1983), and relatively young forest plantations (Southern

1970, Voous 1988).

Two subspecies of the Tawny Owl seem associated primarily with dense, undisturbed

forest conditions. The Himalayan Wood Owl (S. a. nivicola) is resident in the eastern

Himalayas between 1200 and 4250 m in rocky wooded ravines in oak and conifer

forests (Ali 1977; also see fig. 35). It lays its eggs in the hollow of an ancient tree

or in the fissure of a rock cliff without any proper nest (Ali 1949). Scully’s Wood Owl

(S. a. biddu/ph/) is found in wooded ravines in Kashmir and the northwest Himalayas

up to about 3350 m (Ali 1949; also see fig. 35), although its habitat associations are

less well known than those of the Himalayan Wood Owl.

Ural Owl (S. uralen&)-This northern owl of the Old World inhabits tall and open

taiga forests of spruce, fir, and pine, as well as forest glades, bogs, and hardwood

riverine taiga forests, upper elevation fir forests, and lowland forests in eastern Asia

and Japan to 5000 m (de Schauensee 1984; Lahti 1972; Lundberg and Westman

1984; Mikkola 1983, 1987; Voous 1988). Hume and Boyle (1991) characterize habitat

of Ural Owls as remote, undisturbed forests far from human communities. They note

that the species is drawn to old-conifer forest or mixed woodland with clearings

(although in Finland it has begun to use forest bots of spruce and birch and damp

heathland with scattered trees) and that it now nests in buildings and nest boxes

(see fig. 26). Ural Owls nest in natural tree cavities and in abandoned raptor nests.

Mikkola (1983) notes that, in the southern parts of its range, Ural Owls usually breed

in montane forests including beech woods, but elsewhere they prefer dense mixed

forests and conifer forests (personal observation; fig. 40). He reports Ural Owls

nesting in cavities in stumps of a pine or a spruce tree in natural forests, but more

recently they have taken to various nesting sites, including tree stumps, holes in

trees, twig nests, nest boxes, buildings, rock faces, and even flat ground. Thus, the

Ural Owl may not necessarily be closely associated only with old forests but also

may be able to use other habitats in at least a portion of its wide range.

Most of the literature sources note the occurrence of Ural Owls in dense forests.

Scherzinger (1987) however, speculates that Ural Owls depend on open areas and

cannot live in dense woods, and that recent management policies in Scandinavian

national parks to regrow old, virgin woodlands from large clearcuts might reduce prey

densities and habitat suitability for this species. Similarly, Mikkola (1983) suggests

that, although Ural Owls breed in large conifer woods, they prefer the more open

sections and forest edges for hunting, and thus that large clearings of felled trees

are attractive. This conjecture has not been tested scientifically.
Old Forests of Mexico and Central America

11. Diverse Neotropical forests are found in deep canyons

or barrancas of the Sierra Madre Occidental of western

and southern Mexico. Here reside species associated with

dense, undisturbed forests, including Stygian Owl (Ado

sfygius), Vermiculated Screech Owl (Ofus guatemalae),

and Santa Barbara or Bearded Screech Owl (0. barbarus).

12. Upper Sanguita Jungle of San Bias,

western Mexico. These increasingly

scarce old tropical forests of Mexico

occur from the west coast through

Chiapis and Campeche of southeast

Mexico. They contain old-forest owls

such as mottled owl (Ciccaba virgafa)

in western Mexico, and Fulvous Owl

(Sfrix fulvescens) and Stygian Owl in

south Mexico and Central America. In

the higher cloud forests of southern

Mexico and Central America also

occurs the Unspotted Saw-Whet Owl

(Aegolius ridgway/).

13. Many of the tropical forests of southern Mexico and

Zentral America have been cut, burned, and converted to

agricultural fields or pastureland. Often the soil is thin and

provides at best only a few years of production, such as

this corn field converted from west coast tropical forest in

Nayarit, western Mexico.

Hume and Boyle (1991) list David’s Wood Owl (S. david$ as a separate species,

although many authorities consider it to be a strongly marked race of the Ural Owl

(viz., S. uralensis c&avid/). David’s Wood Owl occurs in mountain forests of western

Szechwan, China, and is rare and probably endangered.

Brown Wood Owl-This Indo-Malayan species (S. leptogrammica) inhabits deep

tropical forests and dense hill jungles, from subtropical submontane forests up to

oak-rhododendron forests in the Himalayas, and lowland primary rain forests in

Sunda (Hume and Boyer 1991, Voous 1988; also see figs. 53, 54). The species

avoids contact with humans and with cultivations (Voous 1988) and seems to

closely associate with dense old forests.

16
14. Caribbean slope rain forest of 15. Upper montane cloud forest,

La Selva, Costa Rica. Found in these Monteverde, Costa Rica. These dense

old forests are Black-and-White Owl tropical old forests provide habitat for

(Ciccaba nigrolineata) and Crested mottled owl and Bare-Shanked Screech

Owl (Lophosttix cristata). Owl (OfUS clarkil).

16. Typical fate of tropical forests of

Central America: clearing for pastureland and fuelwood gathering. Under

such land use, little if any suitable

habitat remains for the native oldforest owls. Cordillera de Talamanca,

Costa Rica.

Ali (1962) reports that on subspecies, the Himalayan Brown Wood Owl (S. 1 .

newarensis), is a resident of forests of Sikkim, India, up to about 4000 m. It occurs in deep forests, particularly for daytime roosts (Ali 1977). A very shy bird, it is

disturbed easily on the roost. Much of its breeding biology is unknown, although its

nest has been reported as consisting of “a few sticks and feathers in the hollow of a

forking tree-trunk, on a shelf in a cliff-face, or shallow scrape in the bare ground at

the foot of a rock or large tree in some shady ravine” (Ali and Ripley 1983:256).

17
Owls of the Genus

Ciccaba

The central and south Indian race S. 1 . indranee occurs in deep sholas (dense,

moist forest groves) (Ali 1962; personal observation). It resides in dense evergreen and moist-deciduous forests in mountains of the southern Indian peninsula (Ali and Ripley 1983; also see figs. 37, 38). Smythies (1984) reports that,

in Myanmar, S. indranee (= S. 1 . indranee) occurs in the higher hills, keeping to

deep forests during the daytime, but may venture to glades and more open parts

of the forest in the evening (also personal observation). Throughout Myanmar,

the subspecies occurs in “well-wooded localities” up to nearly 2000 m (Smythies

1984:314).

Mottled Wood Owl (S. osce//ata)-This species is not to be confused with the

Mottled Owl (Ciccaba virgata) of the New World tropics (see below), which in some

accounts (for example, see Stiles and Skutch 1989) bears the same common name.

S&ix oscellata is found throughout much of the Indian subcontinent. It keeps to lightly

wooded plains and frequents mango topes and groves of tamarind and banyan on

village outskirts and in areas of cultivation (Ali 1979; personal observation). One race,

the Northern Mottled Wood Owl, lives in mangos and groves of ancient, densely foliaged banyans and tamarinds, often beside land close to villages (Hume and Boyer

1991). Mottled Wood Owls seem more tolerant of human habitation and agricultural

landscapes than do their sympatric cousins the Brown Wood Owls.

Fulvous or Guatemala Barred Owl-This species is closely related to the Barred

Owl and occurs from south Mexico through Central America in cloud forest and pineoak mountain zones (Peterson and Chalif 1973; also see figs. 18, 19). Hume and

Boyer (1991) describe its habitat as humid upper tropical and temperate pine-oak

forest.

Several other species of Strix are associated with forest habitats, although virtually

nothing is known of their ecologies. Two Southeast Asian species are the Malay

Wood Owl and the Spotted Wood Owl. These two species are combined in some

taxonomies. They inhabit forests, but Clark and others (1978) and Hume and Boyer

(1991) also note that they are found in second growth, town parks, orchards, open

country with scattered woodland, and paddyfields. In South America, the RufousLegged Owl is a little-known species associated with dense tropical forests, and the

Rusty-Backed Owl (also called Rusty-Barred Owl or Brazilian Owl) is found in forests

from southeast Brazil to northern Argentina (Clark and others 1978, Hume and Boyer

1991).

The circumtropical species of Ciccaba resemble those of Strix and, indeed, are

sometimes listed in that genus. They are the southerly forms of the wood owls and

constitute a diverse assemblage of species found throughout many tropical forest

types and elevations.

Mottled Owl (C. wirgafa)-The Mottled Owl widely inhabits dense Neotropical forests

from humid lowlands (fig. 12) to montane cloud forests, as well as semideciduous

and tropical dry forest (Voous 1988), humid forest borders and tall second growth

(Hilty and Brown 1986), and heavily timbered areas (Everett 1977; see figs. 46, 47).

Stiles and Skutch (1989) and Peterson and Chalif (1973) note that Mottled Owls

occur in semiopen, old second growth and in coffee plantations with shade trees.

Hume and Boyer (1991) describe habitat for this species as tropical forest, plantations, and open woods. Thus, the species is not an old-forest obligate. Mottled Owls

18
Other Little-Known

Forest Owls

roost in low thickets by day, and in Costa Rica they also roost in subcanopies of

montane cloud forests (personal observation; fig. 15). Nothing, however, is reported

on their ecological adaptations to specific tropical forest conditions.

Black-and-White Owl-Sometimes considered a subspecies of the Black-Banded

Owl (Stiles and Skutch 1989, Voous 1988), the Black-and-White Owl is found in or

near tall, humid, lowland forests (Peterson and Chalif 1973; personal observation;

figs. 14, 17, 22, 23), in evergreen or gallery forests in arid areas, or sometimes in tall

mangroves (Stiles and Skutch 1989). Hilty and Brown (1986) list habitats as humid

forest, forest borders, tall second growth, and clearings with trees, sometimes near

habitations. Strictly nocturnal, it roosts in thickets by day and often hunts along forest

edges and clearings of damp woods by night.

Two other species of Ciccaba associated with forests in South America include the

Black-Banded Owl found in primary lowland tropical forests in the Amazon Basin

(personal observation; fig. 17) and the rare Rufous-Banded Owl of humid mountain

forests in the Andes mountains (fig. 18). Little is known of the ecologies of these two

species. Everett (1977) suggested that the Black-Banded Owl is showing signs of

adapting to human presence by its regular occurrence in banana and coffee plantations, and Hilty and Brown (1986) noted its habitat as including humid forests, forest

borders, and trees in clearings. Hume and Boyer (1991) denote habitat of the RufousBanded Owl as humid temperate cloud forests of the northern Andes, but that in

Venezuela it is observed in forest openings. They also suggested, however, that

accommodation to human presence is secondary and that removal of rain forest for

monocultures and ranch land almost certainly poses a threat to the species (figs. 20,

21).

The African Wood Owl, the only Old World member of Ciccaba, is widespread south

of the Sahara in evergreen and riparian forests and moist mountain forests (Clark

and others 1978; also see fig. 30). This species prefers forest but only the edges of

denser rain forest tracts, and it survives well in plantations and riparian forests (Hume

and Boyer 1991, Newman 1991). Newman (1991) noted that day roosts are in large

trees. Of the five recognized races, C. woodfordii sokokensis is an endangered, local,

endemic form found only in the Sokoke Forest, Kenya. Whether its endangered status

is due to surrounding deforestation and reduction in its habitat is unknown; it has not

yet been studied.

In addition to the above genera, several other little-studied owl species also are

associated with old, dense, or undisturbed forests, mostly in the tropics. Little is

known of their specific habitat associations, particularly with forests of various ages,

tree densities, degrees of fragmentation, and disturbance histories. These owls are

listed below by genus.

.

Ilophosfrix-Crested Owl of dense Neotropical humid lowland forests (Stiles

and Skutch 1989; personal observation; figs. 22, 23) and tall second-growth and

woodland patches (Hilty and Brown 1986); and the Maned Owl of tropical forests

in west Africa (Everett 1977; but listed in the genus Jubula by Hume and Boyer

1991).
Old Forests of South America

17. Riverine rain forests of the Upper

Amazon Basin, Rio Napo, Ecuador.

Such forests are becoming much more

fragmented as they are cleared by

settlers for agricultural development.

These highly diverse forests contain

lowland interior species such as BlackBanded Owl (Ciccaba huhula), Blackand-white Owl (C. nigrolineata), TawnyBellied Screech Owl (Ofus watsonil),

Pacific Screech Owl (0. cooper&

Spectacled Owl (Pulsatrix perspicillafa),

and the little-known Rusty-Barred or

3andBellied Owl (P. melanota).

18. Peru and Ecuador high cloud

forests. These old forests contain a

high diversity of screech owls, including

Cinnamon (Ofus petersoni), CloudForest (0. marshal/i), Colombian

(0. colombianus), White-Throated

(0. albogularis), Rufescent (0. ingens),

and Roborate (0. roborates) Screech

Owls. Also found in some of these old

cloud forests are Fulvous Owl (S&ix

fulvescens), Long-Whiskered Owlet

(Xenoglaux lowery,), Rufous-Banded

Owl (Ciccaba albifarsis), and Andean

Pygmy-Owl (Glaucidium jardini,).

19. Patches of Polylepis woodland occur

amidst the paramo grasslands in the

high Andean passes west of Quito,

Ecuador, here at nearly 4300 m

elevation. Such cloud forests may

provide habitat for the highland screech

owls and other species. One inhabitant

is the Buff-Fronted Owl (Aegolius

harrisi,), which is a very rare and littleknown denizen of semiopen areas with

old trees, to the edge of paramo in

Colombia and Ecuador.

20. Highland forests of the Andes have been largely

:leared for crops fields and human habitations. Interior

/alley south of Otavalo, Ecuador, approximately 2700 m

elevation.

21. Most of the forest cover in the Andes consists of

plantations of introduced species, such as pines and, as

shown here, Eucalyptus. Along Pan-American Highway,

central Ecuador.

20
22. Lowland Pacific slope tropical forests. As with most

other tropical forests of the world, these forests have been

reduced by clearing and their old forest characteristics

have been compromised by selective cutting of the larger

trees. This forest occurs at approximately 600 m elevation

in Ecuador northeast of the tiny village of Mindo and is

one of the most extensive remaining lowland Pacific

slope tropical forests, although it too is being cleared

(foreground). Owls of the lowland tropical forests of the

Pacific slope include Crested Owl, Spectacled Owl, and

Black-and-White Owl.

24. Ever-growing human densities in South America

Amazonia and lowland coastal areas result in tropical

forests lost to new highway corridors and settlements.

23. Dense tropical forest of the lowland Pacific slope, Rio

Palenque Forest Reserve, Ecuador.

25. Large old specimen of fig (Ficus

sp.) in western Mexico symbolizes both

the plight and promise of tropical forest

conservation for owls of old forests of

the world. In India and parts of Asia,

old-growth Ficus trees are revered for

their sacred qualities and remain uncut,

thereby also preserving old woodlands

for wildlife.

21
Ketupa and Scotope/ia--Many of the fish owls of dense Asian and African

riparian gallery forests (Ali 1962, Ali and Ripley 1983, Everett 1977, Newman

1991; personal observation), particularly Blakiston’s Fish Owl and Tawny Fish

Owl of Southeast Asian dense primary riverine forests (fig. 42); and Pel’s Fishing

Owl, Rufous Fishing Owl, and Vermiculated Fishing Owl of African gallery and

tropical rain forests (fig. 30).

Pulsatrix-Spectacled Owl and White-Chinned or Tawny-Browed Owl of Neotropical lowland forests (figs. 17, 22, 23); and Rusty-Barred or Band-Bellied Owl

of remote Andean highland forests and humid lowland forests (Everett 1977,

Hilty and Brown 1986, Hume and Boyer 1991, Stiles and Skutch 1989; personal

observation; figs. 17, 18, 48, 49).

. Glaucidium-Some of the pygmy-owls of more northerly temperate and taiga

forests, as well as others of tropical forests, associated with mature forest conditions (Stiles and Skutch 1989, Voous 1988; personal observation). Hume and

Boyer (1991) denote habitat for the Northern Pygmy-Owl (G. gnoma) as open

and mature coniferous or mixed forest in western North and Central America.

Other references (also personal observation), however, suggest a more catholic

use of various forests and woodlands. The species might be undergoing a

long-term decline in density, although this is unstudied. Most pygmy-owls seem

adapted to open forests with clearings and can tolerate plantations and human

disturbances of their forest habitats. Some members of this genus are associated

with old or dense primary forest conditions: the little-known Red-Chested Owlet

and Chestnut-Backed Owlet of primary tropical rain forests of west Africa (Clark

and others 1978); the Andean Pygmy-Owl, considered by some as a race of

the Northern Pygmy-Owl, found in wet, dense, montane forests of the Andes

(fig. 18); the Albertine Owlet, rare in forests of eastern Zaire and Rwanda and

threatened by logging and forest clearance for agriculture (fig. 34); and the

Cuckoo Owl found in Himalayan forests and rain forests of Southeast Asia

(Hume and Boyer 1991).

. Ash--Asio species occur variously in dense forest, broken woodland, and open

country. Taxonomies differ as to number of species. Hume and Boyle (1991)

note that the Abyssinian Long-Eared Owl inhabits mountain heaths and interior

highland cedar forests of east Africa and Zaire (fig. 33), and the Madagascar

Long-Eared Owl survives in the restricted and vanishing humid forests of eastern

Madagascar.

l Xenoglaux-Long-Whiskered Owlet, an owl genus discovered in 1976 in upper

subtropical cloud forests of Peru and dense old growth of the eastern slopes of

the Andes (Clark and others 1978, Hume and Boyer 1991; also see fig. 18).

. Uroglaux-Papuan Hawk Owl of dense, hot tropical forests of New Guinea and

Japan.

22
Old Forests of Europe

26. Most of the old forests of Europe

have been harvested and inhabited

for centuries. Populations of Eurasian

Eagle-Owls (/3&o b&o), Ural Owls

(Strix uralensis), Great Gray Owls

(S. nebulosa), and Eurasian Pygmy-Owls

(Glaucidium passerhum passerinum)

have declined or become extirpated

throughout much of the European

landscape but persist in scattered

woodland reserves and parks. The

viability of their mostly isolated

populations is unknown.

27. Many decades of intensive

silviculture in the Black Forest

of southwest Germany have

resulted in even-aged forests of

simple structure, which provide

poor habitat for the native

old-forest owls.

. Ninox-At least six species of hawk owls might be associated with old, dense

forest conditions (Clark and others 1978, Everett 1977, Hume and Boyer 1991):

Rufous Owl (fig. 61) a secondary cavity-nester (Cayley 1975), occurring in thick

woodlands and rain forests of Australia (figs. 59, 60) and New Guinea (Pizzey

1980); the little-known Ochre-Bellied Hawk Owl found in deep virgin forests of

Sulawei, Celebes (Harrison 1973; also see figs. 57-58); Philippine Hawk Owl of

Philippine forests; Andaman Hawk Owl found in forests of Andaman and Nicobar

Islands of the East Indies; Indonesian Hawk Owl of scattered island forests in

Southeast Asia; and Brown Owl of New Guinea lowland forests. Four other

species narrowly endemic to islands of the New Guinea area and likely to be

closely associated with old forests are Admirality Islands Hawk Owl (IV. meek/),

New Ireland Hawk Owl (N. solomonis), New Britain Hawk Owl (IV. odiosa), and

Solomon Islands Hawk Owl (IV. jacquinotl). These four species might also inhabit

lowland tropical forests, but their ecologies are unknown (Hume and Boyer 1991).

23
Implications for

Old-Forest

Management

Summary of Owls in Old

Forests

L-

“. Known Possible

Figure A-Number of known and possible old-forest

owl species in temperate and tropical settings.

. Nesasio-The rare Fearful Owl occurs in lowland primary forest only on three

of the Solomon Islands in Australasia, and little is known of its ecology (Everett

1977).

l AegoliueAll four species of this genus are adapted to forest conditions, although it is unclear if they all typically associate with old forests per se. One

species, Tengmalm’s or Boreal Owl, is associated with old Holarctic conifer

forests (Everett 1977, Ryder and others 1987, Whelton 1989; see figs. 2-3).

Mikkola (1983) notes that, in Europe, the favored breeding habitat of Tengmalm’s

Owl is dense coniferous forest of the taiga belt. The species has a specific preference for spruce but also occurs in mixed forests of pine, birch, and poplar.

Farther south in Europe, it also uses subalpine conifer forests and, in Germany,

pine forests on lower mountain slopes and similar forests on the plains.

Members of other owl genera, notably Athene, Micrathene, Nyctea, Pseudoscops,

Rhinoptynx, Sceloglaux, and Surnia, seem better adapted to various conditions,

including open grassland, Savannah, park woodlands, and broken forests, and thus

are not treated here.

Twelve extant owl species are fairly well known to be associated mostly with dense,

old, or undisturbed forests (table 1, fig. A). These 12 species include 7 tropical or

subtropical forms: Soumagne’s Owl, Bay Owl (which also inhabits high-elevation

temperate forest habitats in low northern latitudes), Forest Eagle-Owl, Brown Wood

Owl, Black-and-White Owl, Crested Owl, and Papuan Hawk Owl; and 5 temperate

forms: Northern and California Spotted Owls, Himalayan Wood Owl, Blakiston’s Fish

Owl, Long-Whiskered Owlet, and Boreal Owl (fig. B). Because so few temperate owl

species are known to be associated primarily with old forests, controversies over the

conservation of old-growth temperate coniferous forests for the Northern Spotted Owl

are a rather unique case.

24
0 Tropical Temperate

OhI. Bubo Ciccaba Scotopetia K&pa f’hoditus Nesesio Xenogtaux

strix Ninox Glaucidium Pulsatrix Asio Lophostrix Aegolius Uroglaox

Figure El-Number of old-forest owl species in temperate and tropical settings, by genus.

Another 71 extant forms-63 tropical and 8 temperate-are known to be associated with forests and also might be dependent on dense, old, or undisturbed forests

(marked with “?” in table 1; also see fig. A), but not enough is known of their ecologies to make definitive designations. These 71 forms include 5 species of Tyfo,

7 species of Otus, 7 species of /3&o, 6 species of Strix, 6 species of Ninox, and the

rest distributed over 9 other genera (fig. B). Several other species, such as the Great

Gray Owl, Flammulated Owl, and Ural Owl, also are found in dense, old, or

undisturbed forests but not as their sole or primary habitats, and thus are not

included in these tallies.

My listing of 71 species unconfirmed as old-forest obligates underscores our overall

poor inventory base and scientific knowledge, particularly in tropical environments. To

aid their conservation, these species should be assumed to be associated primarily

with old forests until further information becomes available. Basic inventories of the

presence and distribution of all species with either known or unconfirmed associations with old forests should be conducted, and nest stands should be protected.

In addition, ecological studies of habitat associations also should be pursued. For the

set of unconfirmed old-forest associates, greater priority should be given for species

(1) in isolated, insular, or increasingly fragmented environments, as with Celebes

Barn Owl, Giant Stops Owl, Fearful Owl, and others; or (2) whose primary habitat

is threatened and in decline, as with many of the tropical species including Scully’s

Wood Owl, Fulvous Owl, Malay Wood Owl, Spotted Wood Owl, Rusty-Barred Owl,

and others.

25
Extinct and Endangered Extinct owls-Clark and others (1978) list nine owl species that became extinct

Owls of Old Forests during historic time. Among these, the Anjouan Island Stops Owl, Mauritius Stops

Owl, Leguat’s Owl, and Mauritius Owl likely inhabited native forests. Their populations probably declined from I

deforestation-of their island

environments. Owls of Old Forests of the World

Recently extinct species

At least two additional species can

be added to this list. Gyro pollens Andros Island Barn Owl Tflo pollens

was a flightless, 1 -m-tall congener Anjouan Island Stops Owl Otus rutilus capnodes

of barn owls that likely occurred in Mauritius Stops Owl Otus commersoni

old-growth Caribbean pine (Pinus Leguat’s Owl Bubo Ieguati

caribaea) barrens of Andros Island, Maruituis Owl Strix sauzieri

Athene blewitti

Bahamas, in association with early

Forest Spotted Owlet

human settlers (see figs. 6-9). It

probably gave rise to local lore of chickcharnies, a mischievous leprechaunlike,

nocturnal imp said to have three toes and the ability to turn its head all the way

around. If disturbed, chickcharnies would impart terrible misfortune. It is possible that

territorial defense behaviors of a meter-tall Tyto could give rise to such legends.

The Forest Spotted Owlet of central India is known from less than a dozen specimens

and has not been reported since 1914 (Ali and Ripley 1983). It was associated with

dense or mature deciduous forests, particularly moist-deciduous jungle and groves

of wild mango near streams, in the Satpura Range of Maharashtra and Madhya

Pradesh States (Ali and Ripley 1983; also see fig. 36). These forests have become

heavily modified during the 20th century by clear-felling and conversion to coppice,

by planting of even-aged stands of teak (Tecfona grandis), and from intensive human

intrusions to extract other forest products (Marcot and others 1991; also see fig. 36).

Although members of Ofus and Glaucidium still inhabit these teak forests (personal

observation), the Forest Spotted Owlet has not been reported recently.

Endangered owls-Clark and others (1978) also listed nine endangered owl species

or subspecies, some of which may be associated with old native forest. Such species

might include Lan Yu Stops Owl of Taiwan, and Nduk Eagle-Owl, a local endemic of

Usambara Mountains, Tanzania (fig. 29). Little is known, however, of the ecology of

either species. In addition, Hume and Boyer (1991) list the Sula Islands Barn Owl

as known from only one specimen and possibly extinct. This species might have

inhabited older native forests, but nothing is known of its habitat associations and

status. They also list the Minahassa Barn Owl as a rare or endangered species in

northern Sulawesi where rich tropical rain forests abound, but nothing is known of

the ecology of the species.

Old-Forest Owls in

Continental and Island

Settings

Of all 83 extant owl species of old forests (table l), almost a third-26 species

(31 percent)-occur only on islands or peninsulas (for example, Malay Peninsula),

and the remainder are found in continental settings (fig. C). This proportion of island

forms is greater than that of all owls of the world regardless of habitat association:

only about one-fourth (26 percent) of the 155 owl species worldwide in all habitats

are found on islands or peninsulas. In general, species occurring only on islands

typically are at much greater risk than are species found in continental settings,

because small population dynamics increase the risk of local extinctions (Gilpin

and Soule 1986). Add to this the loss of old-forest habitats and direct exploitation,

26
Insular

!zi@

Continental-i

Extant Extinct

L ,

Figure C-Number of extant and recently extinct old-forest owl

species in insular and continental settings.

and the threat of extinction to associated owl species greatly increases. Further, of

the six extinct species of owls likely associated with old forests (discussed above),

five (83 percent) were island forms (fig. C). Clearly, island living adds substantial risk

to viability.

If habitats and populations are left undisturbed, many populations not already depressed to moribund levels may survive. For example, Walter (1990) cites the case

of the Socorro Island Red-Tailed Hawk (Buteo jamaicensis socorroensis) persisting

in isolation in small local numbers (20 5 pairs) because it has been undisturbed.

Although this hawk is more of a generalist in habitat and diet than many old-forest

owls, it nonetheless is illustrative of how small-island populations can persist with

local protection of habitats and resources. Few, if any, such studies have been

made, however, of population persistence of old-forest owls on islands.

Threats to Owls of

Forests

Most owls live outside reserves and their fortunes are largely dictated by the

activities of landowners, foresters, farmers, and planners.

Mikkola (1983:311)

The greatest threat to owls of old forests is the direct loss of their habitats. Old

forests are logged throughout the world for wood and other forest products, thereby

resulting in their conversion to young forests or nonforest conditions. Many old forests

have been converted to pasture and croplands, human habitations, and other uses

(Wilson and Peter 1988).

There are few forest conservation reserves estab- Threats to Owls of Old Forests

lished for owls per se throughout the world. In

Europe, as of 1981, only one reserve had been

. Loss of habitat

.

designed for birds of prey at Sabed, near the town lsular settings

*

of Tirgu Mures in Romania (Mikkola 1983). This

Pesticides

. Disturbance

reserve provides habitat for Long-Eared (Asio . Persecution

otus), Stops (Otus stops), Little (Athene noctua), . Collection

and Tawny Owls.

27
~Old Forests of Africa

28. Tropical and subtropical forests of southern Africa

contain Shelley’s Eagle-Owl (B&o sbelley,), Akun

Eagle-Owl (ff. leucostictus), and Fraser’s Eagle-Owl

(f3. poensis). Shown here is Lake Manyara National

Park, central Tanzania, in a rift valley at an elevation

of 945 m. Old tropical forest in foreground, Savannah

with acacia trees behind; baobob tree legacies on

hillsides. (Photo courtesy of David Hays)

30. Dense riverine tropical forests of

sub-Sahara Africa provide habitat for the

scarce Milky or Verreaux’s Eagle-Owl

(Bubo lacteus) and the more widespread

African Wood Owl (Ciccaba woodfordii

sokokensis). Such tropical gallery forests

also contain several species of fishing

owls, including Pel’s (Scotopelia pe/r),

Rufous (S. us&en), and Vermiculated

(S. bouvieri) Fishing Owls. Riparian forest

of Serengeti National Park, Tanzania

along the Grumeti River. (Photo courtesy

of David Hays)

29. Mountain forests northwest of Lake Tanganyika and

possibly within Zaire provide habitat for the rare Prigogine’s

Owl (Phodilus prigoginer). Such habitat appears as these

semideciduous forests occuring near the rim of Ngorongoro

Crater, Tanzania, at 2440 to 2740 m elevation. In the

Usambara Mountains of Tanzania this type of forest

provides habitat for the locally endemic Nduk Eagle-Owl

(Bubo vosselen). (Photo courtesy of David Hays)

31. This mature riparian forest along the Seronera River

in Serengeti National Park, Tanzania, at approximately

1525 m elevation, provides roosting habitat for the Milky

or Verreaux’s Eagle-Owl. (Photo courtesy of David Hays)

28
32. The hagenia forests of Virunga

Mountains, Rwanda, 2440 to 3050 m

elevation, are the home of the mountain

gorilla and eagle-owls. (Photo courtesy

of David Hays)

33. In Zaire, mountain heath and cedar forests are habitat

for the Abyssinian Long-Eared Owl (Ado abyssinicus). Photo

taken in Aberedere National Park, central Kenya, at approximately 3050 m elevation. (Photo courtesy of David Hays)

34. Deforestation in Rwanda includes terracing hillsides for

row crops and eucalyptus plantations (upper right). (Photo

courtesy of David Hays)

29
In the Pacific Northwest, some of the last remaining old-growth conifer forests on

federally administered public lands are being designated as ancient forest reserves,

in part for protection of the Northern Spotted Owl. Current polemics over use and

conservation of these ancient forests, however, are unique only in the degree of

popularity of the issues and the specific kinds of forests involved. The general issues

are timeworn when compared to the fate of many other owl species associated with

old forests throughout the world. Examples of such issues, listed by genus, follow.

Tyfo-Soumagne’s Owl likely is endangered from destruction of its tropical

evergreen forest habitat on Madagascar. This species is included in appendix I

of the 1977 CITES Resolutions and in the IUCN Red Data Book of 1968 and

updates thereto (Clark and others 1978). Conversion of humid rain forests on

Madagascar likely is causing declines of this little-known species (Hume and

Boyle 1991).

Phodilue-The Bay Owl is vulnerable to loss of its evergreen conifer and hardwood

forests in the Himalayan foothills, where lopping and cutting of trees has accelerated

in recent decades from increases in human populations. Over the past century, much

of its habitat in wet evergreen tropical forests of south India and Sri Lanka has been

converted to cropland or even-aged forest or coconut plantations, which has heavily

fragmented remaining habitat into small isolated parcels (personal observation; figs.

38, 39). Bay Owls (and a host of other associated primary and secondary cavityusing species) might be particularly vulnerable to loss of large cavity-bearing trees

in these areas. The related African Bay Owl might still occur in threatened forests of

Zaire (fig. 33), but its response to commercial use of these forests is unknown.

Otus-Forest habitat of the Mountain Stops Owl is “constantly under threat of

destruction” (Voous 1988:32). The Puerto Rican Screech Owl is one of the most

endangered species of Otus because of the progressive felling of its forest habitat

(Everett 1977; and see fig. 10).

On the other hand, Voous (1988) speculates that Flammulated Owls have benefited from the spread of open, arid ponderosa pine (Pinus ponderosa) forests in

the Western United States from human-caused forest fires. Potential threats to the

Flammulated Owl, an insectivore, also might include reduction of large flying insect

populations from pesticide use (Voous 1988) and loss of dead trees with woodpecker

cavities for nest sites (Goggans 1986, Marcot and Hill 1980). Similar loss of cavity

trees in the Himalayas (personal observation) might adversely affect populations of

the related Spotted Stops Owl, one subspecies of the Mountain Stops Owl.

Pesticides also might have had adverse effects on populations of the European

Stops Owl (Otus stops) (Voous 1988). Although this species likely has benefitted

from its association with human-altered landscapes of Europe (figs. 26, 27) and is

not an old-forest obligate, environmental pollution has caused population declines in

the Middle East (Voous 1988). Understanding reasons for population declines of the

European Stops Owl might aid in understanding other, less well-known congeners

associated with old native forests. It is unclear how its populations might be affected

by the current environmental crisis induced by the 1991 Iraqi war, especially pollution

of the atmosphere from hundreds of burning oil wells and other battle-related fires.

Other populations of the European Stops Owl have decreased because of

conversion of woodlands to vineyards in the Rhone valley of Switzerland and the loss

of trees with hollows (Arlettaz 1987, Voous 1988).

30
Old Forests of the Indian Subcontinent

35. The old forests of deodar (Cedrus deogara), blue pine

or kail (finus wallichiana), and chir pine (P. roxburghi,) of

the Himalayas of India, Nepal, Tibet, and Bhutan, have

provided habitat for the Bay Owl (fhodilus badius), Forest

Eagle-Owl (Bubo nipalensis), Himalayan Wood Owl (Strix

aluco nivicola), and Scully’s Wood Owl (S. aluco biddulphi).

However, severe overuse, including terracing, lopping of

trees, fires, and deforestation, has eliminated forest

habitats and resulted in great erosion and slope failures

in many areas.

37. A remnant “preservation plot” of tropical moist

deciduous forest in Kerela, southwest India, containing

:eak (Tectona grandis) and Lagerstroemia lanceolata

n the overstory and Randia dumetorum and Wrightia

Vncforia in the understory. Such forests provide habitat

‘or Brown Wood Owls (Strix lepfogrammica), one of the

Asian cousins of North America‘s Spotted Owl.

36. Much of the older, dry deciduous forests of India has

been removed for agricultural production. Some have been

replaced by plantations of sal (Shoria robusfa) in the north

and teak (Tectona grandis) or exotic species such as

eucalyptus (Eucalyptus globulus) in the center and south.

Forest reserves and wildlife sanctuaries protect remnants

of the original dry deciduous forests. This forest reserve

occurs in Melghat Tiger Reserve, Satpura Hills, Madhya

Pradesh and Maharashtra of the High Deccan Plateau of

central India. It is the last known forest habitat of the Forest

Spotted Owlet (Athene blewit@, not seen since 1914.

38. A tropical wet evergreen rain

forest in Tamil Nadu, south India

(left). These amazingly diverse

forests are characterized by

Dipterocarp trees (for example,

Dipterocarpus grandiflorus,

D. pilosus, D. kerrii, D. gracilis,

and others). Shown here is the

scarce giant evergreen forest of

the Western Ghats, containing

trees of the families Clusiaceae,

Anacardiaceae, Sapotaceae,

Meliaceae, and Lauraceae.

These forests host Brown Wood

Owls, Brown Fish Owls (Bubo

zeylonensis), and, in Southeast

Asia, Spotted Stops Owls (Otus

spilocephalus spilocephalus).

39. The lowland moist evergreen and

wet evergreen tropical forests of southcentral and Southeast Asia have largely

been converted to agriculture and other

land uses. Some of these forests in

upper elevations have been preserved

in recently formed forest and wildlife

reserves. Their small size and scattered

distribution, however, do not guarantee

the long-term viability of associated

old-forest owls, including Forest

Eagle-Owls, Brown Wood Owls, and

Brown Fish Owls.
Loss and conversion of old forests also might adversely affect many other subtropical

and tropical species of Otus, including the Oriental Stops Owl, which is dependent

on such habitats. Clearing of primary lowland rain forests in Malaysia, Sumatra, Java,

Borneo, and the Philippines likely is threatening the Rufous Stops Owl, but nothing

is known of how it might respond to increasing fragmentation of its primary forest

habitat and to growth of secondary forest (Hume and Boyer 1991). Although the

species is not currently endangered, loss of its habitat should be of concern. Collared

Stops Owls and Pacific Screech Owls,

on the other hand, might be more able to

persist in human-altered landscapes and

various forested landscapes in the absence

of old forests oer se. Studies of habitat associations

Ancient Mayan corn crop rotations and

agricultural practices likely led to declines

-Tropical and insular settings

. Protect existing key old forests tracts

-Temperate and troDical

in amount of undisturbed forest vegetation Study deforestation a;d vegetation

in Mexico and Central America (Terborgh

1989). This may have had adverse effects

~ l manipulation

on the Whiskered Screech Owl in the

Neotropics (Voous 1988). More recent and widespread conversions of forest cover

to human habitations and croplands in Mexico likely have caused greater population

declines. The species still remains locally abundant, however, in areas of denser

forest cover.

Populations of the Vermiculated Screech Owl also have declined because of destruction of its New World tropical forests in Mexico, which have all but been cleared

and converted to cropland and secondary scrub forest (Voous 1988; see figs. 12 and

13). Voous (1988:78) notes that “local, geographically marginal populations in Mexico

and South America have already disappeared as a result of habitat destruction, and

some of these probably extinct populations have recently been described as new

subspecies in an attempt to call attention to their former existence (Hekstra 1982).”

The Sokoke Stops Owl, discovered in 1965 by S. Dillon Ripley in the remnants of

the Sokoke Forest on the Kenyan coast, is threatened by loss of its forest habitat

and by specimen collectors (Everett 1977). Between 1956 and 1966, its forest habitat

was halved to 350 km2. Further deforestation poses a threat to the remaining population, as only one reserve of 40 km* has been established (Hume and Boyer 1991).

Its population has been estimated at 1,300-l ,500 pairs and is considered endangered

(Clark and others 1978). Its plight was highlighted in 1966 in the IUCN Red Data

Book.

Continued clearing of tropical mountain forests in Sumatra, Java, and Borneo may

be an increasing threat to the Rajah’s Stops Owl (Hume and Boyle 1991). In Mahe,

Seychelles, new forest harvest methods have led to reduction of upper valley forests,

habitat of the Seychelles Stops Owl. Apparently, the only habitat preserved for this

species occurs in Morne Seychellois National Park. Eventual clearing of highland

forests likely will separate the remaining individuals into one small, isolated population in the park.

In Brazil, loss of lowland dry deciduous tropical forest likely is reducing habitat

available to Black-Capped Screech Owls.

3 2
The Giant Stops Owl also is threatened by loss of its forest habitat in the Philippines

(Clark and others 1978, Everett 1977). Although not a forest bird, the Palau Stops

Owl (0. podarginus) likewise is vanishing because its primary, lowland mangrove

swamp habitat is “fast disappearing” from the Palau islands of Micronesia (Everett

1977347).

B&o-The Forest Eagle-Owl depends

for its survival on the continued existence of the “much endangered” tropical south Asian lowland and hill forests

(Voous 1988:108). Other, less wellknown Asian and African congeners,

including the Akun Eagle-Owl and

Philippine Eagle-Owl, also might be

adversely affected by removal, modification, and fragmentation of their

tropical forest habitats (Hume and Boyle

1991). Mikkola (1983:311) reports that

Ecological Studies Needed

* In insular or fragmented environments

(Celebes Barn Owl, Gian Stops Owl,

etc.)

.

In habitats threatened or in decline

-Many tropical species (Scully’s

Wood Owl, Fulvous Owl, Malay Wood

Owl, Spotted Wood Owl, Rusty-barred

Owl, others)

the Eagle-Owl has been persecuted heavily by humans and “may well fade from

the European avifauna if they are not strictly protected.” In fact, Eagle-Owls were

on a list of “vermin” in France until the early 1960s and as a result, their range

and numbers declined markedly (Mikkola 1983). Captive breeding programs are

underway in Sweden, Germany, and England and are needed in Norway (Mikkola

1983).

Sfrix-The Northern Spotted Owl has become the cause celebre for conservation of

old-growth forests of the Western United States. Its numbers and distribution have

doubtless declined from extensive clearcutting of ancient forests, thereby prompting

a new wave of alternative forestry practices to be considered for use on commercial

forest lands. Barred and Great Gray Owls have evolved greater tolerance for broken

and open forest conditions and do not seem to be in similar peril. In particular, the

Great Gray Owl might never have been very abundant in extensive dense forests

as they usually forage in more open habitats (see footnote 5).

In Eurasia, the Ural Owl likely has suffered declines from widespread conversion of

its northern forests to agriculture or human habitations. The species apparently is

taking to other substrates for nesting, however. Mikkola (1983) notes that in former

times, breeding habitat was old-conifer or mixed forest far from human habitation,

but in the last 25 years this has become more varied. Ural Owls still favor damp

heath forest but now also regularly nest in dry heath forests and spruce bogs, with

additional breeding records in pine bogs and herb-rich forests. Mikkola (1983:171)

concludes that “such adaptability will favor it in the future.”

Because of its tolerance to young forest conditions and its small territory size among

Strix species, the Tawny Owl has persisted in woodlands of Europe. Little is known,

however, of the status of two Asian subspecies, the Himalayan Wood Owl and

Scully’s Wood Owl. As with the northern subspecies of the Spotted Owl, these subspecies of the Tawny Owl seem more dependent on dense or older forests of the

mountains. Loss of ancient trees as nest and roost substrates in the Himalayas from

burgeoning human populations very likely are adversely affecting the populations of

the owls.

33
Old Forests of Eastern Asia

40. Broadleaf hardwood and conifer forests of Far East

Russia supply habitat for Ural Owls, Eurasian (or Northern)

Eagle-Owl, and Brown Hawk-Owl (Ninox scutulafa). This

forest is found in central Ussuriland south of Khabarovsk.

The higher elevation larch and pine forests of Ussuriland

support the more northern Holarctic species including

Great Gray Owl, Eurasian Pygmy-Owl, and Boreal

(Tengmalm’s) Owl.

41. Forest reserves or zapovedniki help conserve oldforest habitats in the Ussuriland region of Far East Russia.

Bolshe-Khekhtsivsky Zapovednik just south of Kabarovsk.

Forests here consist of many locally endemic plants including large cork trees (fhellodendron amurense), two

species of linden (Tilia mandshurica and T. amurensis),

Korean pine (Pinus koraiensis), Manchurian walnut

(&glans mandshurica), Manchurian ash (Fraxinus

mandshurica), and the ancient, relict Mongolian oak

(Quercus mongolica).

42. Undeveloped broad flood-plain forests of Far East

Russia, eastern China, and Korea contain the rare

Blakiston’s Fish Owl (Kefupa blakistonr). Upper Bikin

River Basin, Ussuriland, Far East Russia.

Little is known also of the population status of the Brown Wood Owl. This species is

a close associate of interiors of dense old forests in the Indo-Malaysian area. Like its

Tawny Owl relatives, likely it has suffered declines in recent decades. Its evergreen,

moist deciduous, subtropical submontane, and lowland rain forest habitats have been

reduced greatly. Altering and fragmenting its selected habitats, as with the conversion

of wet evergreen forests to teak plantations in south India (fig. 39) and Sri Lanka,

may pose an even greater threat to the Brown Wood Owl than to the Tawny Owl,

which may be more tolerant of forest edges and openings.

34
43. Across the border from the Russian Far East is

Heilongjiang Province, northeast China, where lowland

forests have long since given way to rice paddies, agricultural fields, and pasturelands. Old-forest owls of the Far

East are essentially extirpated throughout most of eastern

China under the enormous and growing human population

pressures for land use.

44. “Artificial forests” of larch (Larix olgensis and

L. gemenii) and pine (Pinus sylvestris var. mongolica)

have replaced the diverse native forests of Kinghan fir,

Korean pine, Mongolian oak, and many other species,

throughout much of eastern China. These planted forests

cover vast acres but likely provide poor habitat for many

of the native species of old-forest owls.

45. Eastern China has seen great episodes of deforestation.

its rich, loess-covered agricultural fields are subject to

tremendous wind erosion and gullying, further reducing

suitability for growth of forests. Restoration of native forests

is virtually unheard of and most forest cover consists of

plantations of three or fewer tree species where dozens

once stood. Few if any old-forest owls have survived these

changes.

Partly sympatric with the Brown Wood Owl is the Mottled Wood Owl, which is more

tolerant of human-altered landscapes and may not be as affected by loss and conversion of old-forest habitats. Recently, measures have been taken to protect wet

evergreen forest stands in Kerela and Tamil Nadu states in south India, such as with

the creation of Indira Ghandi Wildlife Preserve. These are major positive steps that

will aid in conserving habitat for Brown Wood Owls, Mottled Wood Owls, and their

old-forest associates (for example, Uniyal and Surendrnathan Asari 1988).

35
1Examples of Forest Distributions and Owl Ranges

Pntral and South America 1

I46. Distribution of South American tropical rain forest, moist

deciduous forest. and montane forest:

47. Range of Mottled Owl (Ciccaba

virgafa). Note coincidence with

distribution of tropical forests.

50. Range of Cloud-Forest Screech Owl (O&s marshal/o

in Andean cloud forests of Peru. An example of a locally

endemic species with narrow distribution.

48. Range (above) of

Band-Bellied Owl (Pulsatrix

melanofa) coincides with

lowland tropical forests

east of the Andes.

49. Band-Bellied Owl (left).

P”

51. Cloud-Forest Screech Owl.

J

36
A more subtle potential threat to the Brown Wood Owl and associates may be the

intensive use of forests by humans for forest products other than commercial timber. In Southeast Asia, such forest products and uses include gathering of bamboo,

canes, resins, and bidi leaves; collection of deer antlers; falling of hazard trees; selection cutting of trees for poles and construction; lopping of tree limbs for livestock

fodder; and grazing livestock. Such use, if conducted in moderation, should pose no

threat to the owls or their habitats. Unconstrained use, however, results in forests of

substantially sparser canopy and ground cover and lower overall plant and animal

diversity (personal observation). This use is apt to adversely affect resident owl

populations by reducing forest cover and availability of trees with nest cavities.

Such potential effects on owl populations need further study.

Little is known of the population status of Fulvous Owls in the Neotropics. It can

be surmised that cutting of their associated pine-oak and cloud-forest habitats has

detrimental effects on population sizes of this and other related owl species of the

New and Old World tropics, including the Malay Wood Owl, Spotted Wood Owl,

and Rufous-Legged Owl.

Ciccabe-The Mottled Owl does not seem threatened as long as tropical forests

remain protected in sundry parks and reserves, such as the cloud forests of

Monteverde Biological Preserve in Costa Rica (fig. 15). Little is known of the

population status of other tropical members of Ciccaba, although it can be surmised that reduction of tropical gallery and evergreen forests has adversely

affected Black-and-White and Black-Banded Owls in the lowlands and perhaps

also Rufous-Banded Owls in the Andean highlands.

Other genera-The Blakiston’s Fish Owl is threatened with the removal of the

taiga forests on which it depends in Japan and the Russian Far East (Voous 1988;

personal observation). The Japanese race Ketupa 6. blakisfoni of Hokkaido and

Kunashire Island numbered 50 birds in 1984 (Hume and Boyle 1991) and is

endangered from loss of its dense, primary forest habitat (Clark and others 1978).

in the Russian Far East, its primary habitat is mixed old-growth forests of broadleaved and conifer trees; most of these forests have been logged and the species

persists only in small, isolated populations in broad, mostly undisturbed valleys of

the Amur, Bikin, Khor, and a few other major rivers of the region. Likely, it is mostly

extirpated in northeast China because of conversion of vast native forests to agriculture, pasture, or forest plantations (personal observation; figs. 43-45). Other

threats to its persistence include increasing human populations, seledtive harvesting

of its nest trees, and disturbance from tourists, although it seems to be taking to use

of nest boxes in Hokkaido (Hume and Boyle 1991).

The Eurasian Pygmy-Owl (Glaucidium p. passerinum) had disappeared from the

Black Forest mountains of Germany because of intensive timber management

activities, including parcelling of the spruce-fir forests and clearcutting of old-growth

forest stands (K&-rig 1981; see figs. 26, 27). More recently, the species has been at

least partially restored with the use of nest boxes (Voous 1988). The Albertine Owlet

likely is endangered because of logging and clearing of the Nyungwe Forest in

Rwanda and mining in the ltombwe Mountains of central Africa (Hume and Boyle

1991). Zaire and Rwanda have planned, but not yet implemented, some conservation

measures. Other species, including Papuan Hawk Owl, Ochre-Bellied Hawk Owl,

37
Restoration of Old

Forests

Indonesian Hawk Owl, Stygian Owl (Asio stygius; see fig. 1 l), and Madagascar

Long-Eared Owl, also increasingly might be threatened from reductions in their

tropical forest habitats.

Certainly, there are many other threats to forest owl species of the world, including

disturbance by photographers, birders, and tourists, as with Eagle-Owls in Britain

and Great Gray Owls in California; use of pesticides; poisoning, shooting, and

electrocution; and collecting of eggs and specimens. Another major cause of habitat

loss is reduction of riparian forests from drainage of wetlands, streams, and lakes.

This probably has reduced numbers and distributions of Eagle-Owls and Brown Fish

Owls throughout Europe and the Mediterranean region, particularly in Israel (Mikkola

1983) and India (personal observation).

Cleared old native forests rarely are returned to original or near-original condition.

I am aware of no scientific study that has demonstrated unequivocal success in

intentionally restoring an owl species or other wildlife associated with ancient forest

conditions through use of reforestation or other specific forest management practices.

Several projects underway deserve special mention and support, however.

In temperate conifer forests, environmental concerns for loss of old-forest habitats

are fostering a new era of forest management techniques. In part, such techniques

are aimed at maintaining and restoring at least some older forest conditions on public

commercial timber lands of the Pacific Northwest (for example, Franklin and others

1986, Klinka and others 1990). Silvicultural prescriptions are being written to demonstrate and test how well old-forest components, such as large live trees, large snags

and down logs, and dense and diverse vegetation structures, can intentionally be

maintained or induced by direct stand manipulation. One phase of these studies

involves testing behavioral and population response by the Northern Spotted Owl

on National Forests. Indeed, one conservation strategy for managing habitat for

Northern Spotted Owls on Federal forest lands (Thomas and others 1990) calls for

developing and testing such silvicultural techniques as an integral part of the

long-term success of the strategy. Such new forestry tactics are best applied in a

careful scientific program of hypothesis testing to evaluate effects on forest stand

structure and composition, production of desired commodities, and particularly

long-term response by owl populations. In using an approach of this type, existing

scarce and declining old forests should be protected at least in the interim (Johnson

and others 1991).

Restoration of wetlands and associated riparian gallery forests in Europe and Asia

could aid in recovery of associated owl species. Brown Fish Owls, Eagle-Owls, and

the host of other fishing owl species would benefit.

Several owl species primarily associated with old forests also show some use of

mixed-age or older secondary forests. These species include the Tawny-Bellied

Screech Owl, Fraser’s Eagle-Owl, and perhaps the Spotted Owl in limited parts of

its range. Manipulation experiments to test the response of these species to carefully

applied silvicultural prescriptions might help identify new methods for conserving their

habitats and allowing some degree of use of forest commodities. Such experiments

should be conducted, however, as strict scientific and statistical studies, as aberrant

case observations can easily lead to overestimating the degree of adaptability of

these species.

38
In tropical forest systems, restoration projects are being proposed or implemented to

help bring back old-forest conditions. Among these is the restoration of dry deciduous

tropical forests in the Guanecaste region of northwestern Costa Rica (Jantzen 1988).

Success of this project might benefit species of Ciccaba, Ofus, and other tropical

genera and concomitantly would provide for sustained use by humans for farming

and livestock grazing. In the Western Ghats mountains of southern India, silvicultural

monitoring projects are aimed at restoring some of the highly modified and fragmented wet evergreen forests from converted teak plantations (fig. 37). The restoration also might help recover Forest Eagle-Owls and Brown Wood Owls in these

areas (personal observation). Many other tests of effects of forest openings, patch

cuts, and canopy gaps in Brazilian Amazonia (Lovejoy and others 1986) and Caribbean slope rain forests of Costa Rica (for example, Denslow and others 1990) are

being explored as well. Results of these and other studies can be used to identify

forest management activities that can restore or maintain old-forest owl species

even in the presence of human use of forests.

Nest Boxes Are Not a

Long-Term Solution

Many forest owl species benefit from nest boxes or artificial nest platforms, including

Tawny (Southern 1970), Barred (Johnson 1987), Great Gray (Bull and others 1987),

Flammulated (Hasenyager and others 1979), Striated Stops (0. brucei; Voous 1988),

European Stops (Arlettaz 1987, Barthos 1957, Kadochnikov 1963, Randik 1959),

and Collared Stops (Pukinsky 1977) Owls. Mikkola (1983) also lists the Hawk

(Surnia u/u/a), Tengmalm’s, and Little Owls as readily using nest boxes.

By far, however, most of these species are notably more generalist in the ages and

kinds of forests they inhabit than are their old-forest congeners discussed in this

report. Similar nest-box programs for owl species more closely associated with old

forests, such as for Brown Wood Owls and Northern Spotted Owls, likely would not

meet all their life needs found in old forests, including availability of prey and thermal

and predation cover. Possibly for this reason, the Northern Pygmy-Owl has not taken

to nest boxes as has its European congener the Eurasian Pygmy-Owl (Voous 1988),

and the Northern Spotted Owl has been induced to use nest boxes or artificial nesting

platforms only in isolated cases.6 The removal and prevention of old rotting wood in

European forests by modern forestry programs is detrimental to breeding successes

of Hawk, Tawny, Ural, Tengmalm’s, and Pygmy Owls, who use natural fissures and

tree cavities as nest sites (Mikkola 1983). In Sweden and Finland, however, many

nest boxes have aided in increasing local numbers of Ural Owls. If instituted for

old-forest owls, nest-box programs should first be conducted to scientifically test

hypotheses of behavioral and long-term population responses rather than as a

full-fledged management program (Marcot and Gardetto 1980).

Interpreting Habitat

Associations

Studies of the Northern Spotted Owl have described clearly its selected habitat as

mature and old-growth conifer forests (Thomas and others 1990). Nevertheless,

many people interested in the commercial values of its preferred habitat cite occurrence of the subspecies in second- and young-growth forests as evidence of its

“adaptability” (for example, Craig 1986). Studies have revealed that such atypical

associations occur for only a small portion of the subspecies, if at all (atypical

associations with young forests also are reported with other old-forest owl species).

6 Personal communication. Jeffery Mattison, Six Rivers

National Forest, Fish and Wildlife Unit, 1330 Bayshore Way,

Eureka, CA 95501.

39
Examples of Forest Distributions and Owl Ranges

Southeast Asia

5 4. Brown Wood Owl (far right).

Tropical rain forest

Moist deciduous forest

m Montane forest

2. Distribution of rain forests of the Indo-Malaysian region.

3. Range of Brown Wood

)wl (Strix lepfogrammica) in

ioutheast Asia. Note general

oincidence with distribution of

,opical rain forests.

L

40
. _

i

CQ..

55. Range of Bay Owl (Phodilus badius) in Southeast Asia.

c .

57. Range of Ochre-Bellied Hawk Owl (Ninox pen/em) in

tropical rain forests of Celebes.

56. Bay Owl.

58. Ochre-Bellied Hawk Owl.

41
Also, within young forests, Northern Spotted Owls typically are found tightly associated with elements or small patches of old forests (Forsman and others 1977,

Thomas and others 1990). The Northern Spotted Owl evolved in association with,

and is adapted to, old forests. Populations likely would fare poorly in landscapes

with highly fragmented old forests or with purely young-forest conditions (Thomas

and others 1990).

Ongoing research is testing these

concepts and assessing how well Conservation Activities Needed

silvicultural manipulations can provide

old-forest elements for Spotted Owls l Create old-forest reserves

and other old-forest associates in . Restore old-forest conditions

commercially managed forest lands l

Study behavioral and population response

(Nyberg and others 1987). Also of Restore wetlands, riparian habitats

particular relevance to management

1 Nest boxes 7

. . . .

of Spotted Owls would be an understanding of its old-forest congeners, particularly the Himalayan Wood Owl and

Scully’s Wood Owl, in their increasingly fragmented and altered mountain forest

habitats. Unfortunately, no ecological or demographic studies seem to have been

conducted on these populations.

Some species of Ofus, such as the European Stops Owl, the Striated Stops

Owl, and the Collared Stops Owl, seem to do well in cultivated and humanaltered habitats. Other congeners, however, such as the Mountain Stops Owl

and the Oriental Stops Owl, are associated primarily with old, denser forests

and do not tolerate human alteration of landscapes. Similarly, among species of

Strix, the Barred Owl and Tawny Owl likely are more tolerant of human-altered

habitats and concomitant invasions by potential predators and competitors than

are other congeners such as the Brown Wood Owl and the Spotted Owl. In the

same way, among species of B&o, the Great Horned Owl is more catholic in ages

and structures of forests it inhabits than is its Asian cousin, the Forest Eagle-Owl.

It should be no surprise that the various species of a genus complex, such as Strix

and Otus, have evolved to specialize in use of different environments including

undisturbed, old forests. Nor should it be a surprise, following this evolutionary

history, that no one species of a given genus exhibits the full range of ecological

adaptations and habitat associations as seen among all its congeners, just as no

one individual of a species exhibits the behavioral variation of all races of the

species (Ruggiero and others 1988). Thus, the best way to ensure the continued

existence of all species of each genus complex is to provide for the full range of

habitat conditions, including old forests, needed by each species.

Forest Owls in Human

Cultures

Many species of forest owls have played prominent roles in myths and religious

beliefs (Holmgren 1988). The plaintive song of the Mountain Stops Owl is known in

legends of the mountainous tribes of Myanmar (Smythies 1953, Voous 1988). The

Oriental Stops Owl is the subject of folklore in Japan and Korea, its call associated

with the mystical treasures of Buddhism (Austin and Kuroda 1953, Voous 1988).

42
1 Examples of Forest Distributions and Owl Ranges

Austr&ia

m Moist rain forest

Wet sclerophyll forest _

m Cypress pine forest

Riverain forest

~~~~g~ x::& Open woodland and scrub

59. Distribution of rain forests in Australia.

60. Range of Rufous Owl (Ninox rufa) in moist rain forests of

northern Australia.

61. Rufous Owl (right).
Old-forest owls often are associated with sacred, large trees in riparian gallery

forests, near temples, and in cemeteries. In India, the Forest Eagle-Owl plays a

major role in many legends and is said to be found calling from Hindu cemeteries

that are often the only local bastion of old-growth forests with large hollow trees

and snags.‘The Brown Wood Owl, Forest Eagle-Owl, and Brown Fish Owl are

found in sholas and gallery forests of Ficus near waterholes and streams in northern

and southern India, sacred areas with mundirs and temples (personal observation;

fig. 38). In a sense, then, many of these owl species serve as indicators of the

religious value of a forest.

The Collared Stops Owl has survived on Java and Borneo possibly in part because

of the ill omen or reverence it represents in legends there (Voous 1988). In China

and Korea, these owls are used for medicinal purposes and many have been taken

annually for this purpose (Austin 1948, Gore and Won 1971, Voous 1988). For the

most part, however, the Collared Stops Owl has adapted well to areas of human

habitation.

Ultimately, the Spotted Owl finds itself in similar circles of controversy over forest

management as have many other species in other parts of the globe. The fate

of Brown Wood Owls in southern India, Sikkim Bay Owls in the Himalayas, and

Crested, Black-and-White, and other Neotropical owls in Central and South America

similarly are caught in disputes over human use of their selected old-forest habitats.

Such controversies include the closure of local forests to commercial timber harvest,

national policies in India that have brought hardship to some local tribes and villagers.

In response, the Government of India has instituted retraining programs to school

the former loggers to become environmental educators and field tour leaders for

the growing industry of environmental tourism (Panwar and Rao 1990). Perhaps by

similarly incorporating the Spotted Owl once again into the culture of North America

through recreational, aesthetic, artistic, scientific, and even ethical interests, it can

play a legitimate role in the well being of human societies and thereby continue to

persist in some of the least disturbed and oldest temperate forests the world now

knows.

Acknowledgments I thank Evelyn Bull, Carl Marti, David Wilcove, and Jon Winter for helpful technical

reviews of the manuscript, and Steven McDonald for a policy review. This paper

is dedicated to the many field biologists of Federal and state forest management

agencies, universities, research stations, and other private and public organizations

whose work is helping to protect owls of old forests throughout the world.

Measure 1 meter (m) = 39.37 inches or 3.28 feet

Equivalencies 1 square kilometer (km2) = 0.3861 square mile

’ Personal communication. V.B. Sawarkar, Wildlife Institute of

India, P.O. New Forest, Dehra Dun 248006, India.

44
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51
Appendix A: The

Son

f

s of Sfrix

Intro uction

The past decade has seen an exponential increase in studies, inventories, and

monitoring of Spotted Owls (Sfrix occident&s) on Federal, state, and even private

lands throughout the Western United States and Canada (for example, Allen and

others 1989, Fredrickson and others 1990, Simon-Jackson 1989). The USDA Forest

Service (1988) has been using protocols for monitoring Northern Spotted Owls (S. o.

caurina). Such protocols stipulate the use of nocturnal and diurnal calling surveys

(Forsman 1983) to locate owls (see also Johnson 1986).

Spotted Owls have a wide variety of songs and calls (Fitton 1991, Forsman and

others 1984). Some of these vocalizations have been recorded on audio tape for

use in conducting calling response surveys in the field and for training of personnel

to recognize owl species (see also Ganey 1990, Laymon 1985, and USDA Forest

Service 1988 for studies of Spotted Owl vocalizations and their use in monitoring

surveys). In recent years, a small army of field personnel have scoured many types

of forests for presence of Spotted Owls by using taped or vocalized calls. What these

biologists might not realize is that the Spotted Owl has many cousins throughout the

world with rather similar vocalizations. The purpose of this paper is to review the

various Strix species and their calls. Herein, I compare descriptions of vocalizations

from field guides and other sources, many not commonly known by most field-going

wildlife biologists. I hope this brief review of vocalizations of 13 species of Strix’ and

5 species of Ciccaba (appendix B) will highlight similarities and help foster a greater

understanding and appreciation for Spotted Owls and their relatives.

Origin and Purpose of

Vocalizations

The evolution of vocalizations by birds, including owls, can be attributed to acoustic

properties of their primary habitats, as well as to selective forces of sexual recognition and other intraspecific and interspecific interactions. Specific vocalizations

given in particular instances are often the result of mood, pair and breeding status,

time of day, age and sex class, and season. Vocalizations generally are given to

announce and defend territories for mates or resources or to maintain contact with

mates or young (Jellis 1977).

With few exceptions, most species of Strix occupy woodland and forested habitats

mostly in the Holarctic zoogeographic region. A few species occur in the Neotropical

and Oriental zoogeographic regions (Voous 1988). Most Strix species are typically

monogamous and vocally defend territories for mates or resources. Many vocalizations for territorial defense are loud and forceful, and they consist of various series

of several individually recognizable hooting notes. Other vocalizations, projecting a

greater state of agitation as when confronting a conspecific at close range, typically

include various shrieks, howls, and screams, such as with the Spotted Owl (Forsman

and others 1984). Still other sounds include softer calls given by young as foodbegging calls, or by females to locate and maintain contact with their young.

Vocalizations of Strix The following accounts describe many of these calls listed by species. Vocalizations

for many species are yet undescribed in published material.

I recognize the long-acknowledged difficulty in describing bird sounds with words or

phrases (Jellis 1977). Sound spectrograms are vastly superior to words for denoting

durations, frequencies, harmonics, and overtones. They are difficult to obtain, however, for as full a set of species as offered in this report and are less mnemonic than

are the more subjective descriptions herein.

’ Fourteen species, if S&ix davidi is considered separately

from S. uralensis.

52
Strix of the Nearctic

Region

Spotted Owl (S. occident&is)-Spotted Owls are found throughout western and

southwestern North America from southern British Columbia into the mountains of

northwestern Mexico. Spotted Owl vocalizations are quite varied, and have been

well described by Forsman and others (1984). They include high-pitched hoots, like

the barking of a small dog, usually in groups of four, as in hoo,who-who,whooo

(Peterson 1961), the last note drawn out and descending in pitch. These are location

calls given by both sexes, with the female’s call being slightly higher in pitch.

When more greatly agitated, Spotted Owls also give a call consisting of a rising

inflection of whoo, whoo, hoo, hoo, hoo, hoo-hoot-hoot, hoo-hoot-hoot, cut off at

the end or occasionally terminated with a descending hoooo. This call may escalate

to a shrill kre-ick! kre-ick!, which in turn might escalate to a rising whistle, which

rises most abruptly at the end and is cut off sharply, as in wheee-et! or cooo-weep!

This is often given repeatedly and is a contact call, more often given by the female.

Other calls include a crowlike bark khaw khaw khaw, given by the female. Foodbegging calls given by the young or female-young contact calls given by the female

generally are heard only at close range and are not commonly encountered during

field surveys.

Barred Owl (S. varia)-Barred Owls occur throughout southern Canada, the Eastern

United States, and into northeastern and central Mexico. Udvardy (1977) described

calls as a distinctive, rhythmic series of loud hoots, who-cooks-for-you, whocooks-for-you-all (see also Forrand 1983). The call also has been described as

hoohoo-hoohoo-hoohoo-hoohoooaw, the ending aw being characteristic; and

other calls include sounds like the barking of a dog (Peterson 1961; personal

observation of the author). Still other calls include a hoot that terminates with a

diminishing waahh-ah that fades away, and a “pleasant duet of the pair with one

on a higher tone and twice as fast, and a number of weird chuckles, screams, and

assorted haunted-house noises” (Tyler and Phillips 1978:138-l 39).

Great Gray Owl (S. nebu/osa)-Great Gray Owls are circumpolar and found in

boreal regions of North America, Europe, and Russia (Holarctic distribution). Calls

include a series of deep, resonant whoos (Udvardy 1977), also described by

Peterson (1961) as a deep booming whoo-hoo-hoo and deep single whoos. The

male’s territorial call is a regular, deep, booming series hoo-hoo-hoo, which can

rise gradually in pitch (Hume and Boyer 1991). In Far East Russia, the calls are a

loud and muffled hoo-hoo-hoo (Flint and others 1984). Perrins (1987:140) reported

the voice of the male as “regular, deep growling or booming hoots and ke-with calls”

similar to those of the Tawny Owl but deeper.

Mikkola described the primary territorial song given by the male (and sometimes by

the female) as a series of up to 8 to 12 regularly spaced ho notes given at a rate

of 1.5 notes per second, the series lasting 6-8 seconds, with 33 seconds between

series. The most common call of the female is a soft mellow hoot used to communicate with her mate at the nest. Various depictions are vee-vee, nieh-nieh, and

whoop. In addition, both sexes give a series of rapid double notes as a defensive

or warning cry. The female also gives a loud heronlike squawk or bark at the end

of a series of notes ranging from vigorous hooting to high-pitched wails and squeals,

as in alarm.

53
S&ix of the Neotropical

Region

Fulvous Owl or Guatemala Barred Owl (S. fo/vescens)-This species occurs in

tropical and temperate forests of southern Mexico and northern Central America. The

call is described as a four-noted huho, huhoo, the combination sometimes repeated

twice rapidly (Edwards 1972). Fulvous Owls previously were considered by some to

be a race of the Barred Owl (Davis 1972, Eck 1971, Peters 1940). Their calls were

described by Peterson and Chalif (1973) as hooting similar to that of the Barred Owl.

Indeed, the repeated four-note series sounds similar to the location call of the Barred

Owl (see above). Its hooting calls also have been described as similar to those of the

Spotted Owl (Dickey and van Rossem 1938, Monroe 1968, Voous 1988).

Rusty-Barred Owl (S. hy/ophi/a)-This species and the Rufous-Legged Owl are

the only St&species in South America. The Rusty-Barred Owl inhabits woodlands

of the central part of the continent, and its calls include a rolling rrrrro; a rhythmic,

descending gutteral gu gu gu gu gu, u, u, u, u; and a long-drawn i-u-a (Hume and

Boyer 1991) or ascending and then descending scratchy scream sounding like a

frightened human.

Rufous-Legged Owl (S. rufipes)-This species is found in southern South America.

I could find no reports of its vocalizations. However, the recordings by Hardy and

others (1990) include 2-note and 4-note songs, sounding like a scratchy prr-prrrrr

(sometimes doubled in the 4-note song), the second note accented and descending

in pitch; and the same song with 2 or 3 brief introductory notes and 2 ending notes

of the same prr quality added.

S&ix of the Palearctic

and Oriental Regions

Tawny Owl (S. &co)-Tawny Owls are found throughout Europe and in disjunct

populations in the Near East, Far East, and southeastern Asia. Their voice, as

reported by Perrins (1987) in Britain and Europe, is quite variable with the male

giving a tu-whit-tu-whoo and the female responding ke-wick; the young give a

scratchy persistent ti-sweep. In Far East Russia, Flint and others (1984) wrote that

the male gives a hoo-hoo-hoooo, and the female a kyouyouyouveeh. In Southeast Asia, King and others (1975) reported the voice as a high, screeching, sharply

accented call of two syllables, buku.

Hume and Boyer (1991:139-140) described the call as “a long, pure, or faintly

wheezy, hoot, followed by a short pause, then a brief, abrupt hu and a long,

resonant, wavering huhuhuhoooo.” The contact call is kewick, and as followed

by a hoot has given rise to the “somewhat inaccurate” depiction as tu-whit-tuwhoo (Hume and Boyer 1991). Fledged young have a similar call, but it is a more

wheezing, strained, lower, and less explosive tsi-weep.

Mikkola (1983) denoted their calls as the most diverse of all European owls, with

10 different basic calls given by breeding adults and 5 calls given by young. The

basic call of the male serves for marking territories, during courtship, and when

bringing food to the female and young. This call is a long drawn out hooo, a pause

of 2 to 6 seconds, an abrupt and subdued hu, followed at once by a long, resonant

huhuhuhooo. The females’ calls are less clear-phrased, ending with a wailing

wow-wow-hooo. Other calls include an oo-trill given by the male after delivery

of prey and as a territorial conflict call; this call also has been described as a loud

discordant “caterwauling.” Another call is a hissing trill co-co-co-co-co-co given

during courtship and territorial fights.

54
In India, calls of one subspecies, Scully’s Wood Owl (S. a. biddu/ph,), have been

listed as “a loud hoo....hoo..hoo-ho-ho-hooo, the final hoo being somewhat drawn

out. There is a pause of about four seconds after the initial hoo, and half a second

between the second and the rest of the concluding rolling note” (Ali and Ripley 1983:

257; similarly described in China by de Schauensee 1984). Other calls of this subspecies include a loud quack and a soft coo, the latter similar to those of a ring

dove or turtle dove (Ali and Ripley 1983:257), and a khawak uttered when flying

about at night, occasionally when perched (Ali and Ripley 1983:257). Ali and Ripley

also noted that Scully’s Wood Owls begin calling an hour or so after sunset from

some exposed treetop and repeat the call for 10 minutes at a time, with a pair or

several birds answering one another. The authors also described calls similar to

the above for the Himalayan Wood Owl, S. aluco nivicola, including a “loud

hoo..hoo..hoo-ho-ho-hoo, the final hoo drawn out;” and that the call sounds

“sometimes merely as a hurried deep low hu-hoo” (Ali 198962).

The contact call of the Tawny Owl is kewick and is given mostly by the female

(Mikkola 1983). This is quite similar to the contact calls given by female Spotted

Owls. Mikkola (1983) described several other calls of Tawny Owl adults and young.

Ural Owl (S. u&en&)-The Ural Owl occurs in middle north temperate latitudes of

Europe and Asia. Perrins (1987) reported the Ural Owl’s calls as consisting of both

hooting and ke-wick types, both deeper and more barking than those of the Tawny

Owl. Flint and others (1984) noted that the Ural Owl’s call in Far East Russia is a

barking, high-pitched hey-hey-hey or kaoo-vekk. Calls in China were reported by

de Schauensee (1984) as a long, quavering hoot, and also a barking khau-khau

and a harsh ke-wick. Young Ural Owls give wheezy notes.

Hume and Boyer (1991:146) noted that its call is a double barking hoot, and that

pairs might call together. The song is a “simple repetition of hoots, huow-huowhuow, the female’s version being lower, weaker and harsher in quality.” The male

also gives a call consisting of wohu, a 4-second pause, and then a wohu-huwohu,

for territorial defense or mate contact. Ural owls also give a loud, sharp korrwick,

longer and harsher than the kewick note of Tawny Owls. Young give food-begging

notes.

Hume and Boyer (1991:148) also separate the David’s Wood Owl (S. &vi@,

which others consider as a strongly marked race of the Ural Owl. In their account,

the David’s Wood Owl gives a “long, quavering hoot and barking khau khau.”

Mikkola (1983) described the courtship song of the male as a deep hooting

wohu...wohu-huwohu, with a 4-second pause in the middle. Other calls include

a barking huow-huow-huow given by the male; a single huu given by the male in

excitement; various calls at the nest given by the female, including barking, gobbling,

chuckling, and hissing; and a sharp cry korrwick, harsher and longer than similar

notes of the Tawny or Great Gray Owls.

Brown Wood Owl (S. /eptogrammica)-A resident of deep mountain forests in

much of the Oriental zoogeographic region, the Brown Wood Owl is poorly studied.

The 15 recognized races differ considerably in size and degree of isolation (Hume

and Boyer 1991). The outer ear structure is less complex than that of other Strix

species, leading Hume and Boyer (1991) to suggest its grouping with Ciccaba.

55
King and others (1975) listed calls as a l-second series of four deep musical notes,

goke, goke-galoo, with the first note emphasized and a wide variety of similar calls.

In China, the voice was cited by de Schauensee (1984) as a mellow, musical, hollowsounding tok...tu-hoo, often repeated, with the tok note in undertone. In Sri Lanka,

the voice is a sonorous huhu-hooo (Henry 1971). Other calls include a “barking

wow wow, undoubtedly signifying alarm” (Voous 1988:208).

Ali (1962) described the call of the Himalayan Brown Wood Owl (S. 1 . newarensis)

as “a deep four-noted hoot, hoo...hoohoo...hoo.” Other calls include what is probably

a conversational note between a pair at dusk-a low, sonorous koo-krrri, rather like

a domestic pigeon-as well as querulous screams and loud snapping of the bill on

detection of an intruder near the nest, and when apprehensive (Ali 1962), the calls

sometimes being given diurnally (Ali and Ripley 1983). Calls of S. 1 . newarensis also

have been described as “a low double hoot tu-whoo (Ali and Ripley 1983256).

Smythies (1984: 310, 313) described calls of the Brown Wood Owl, Strix indranee

(= S. leptogrammica indranee) of Burma, as a deep musical call of four syllables,

who-hoo-hoo-hoo, with the emphasis on the first note, lasting about 1 second; and

“diabolical screaming shrieks...like that of a demented person casting himself over

a precipice.” Ali and Ripley (1983:256) described the calls of S. leptrogrammica

irtdranee as a “mellow, musical, hollow-sounding tok...tu-hoo repeated every few

seconds,” the initial tok (sometimes twice) uttered as a low undertone and audible

only at close range (also mentioned in Ali 1989 for S. 1 . newarensis). Birds were

described by Ali and Ripley as being particularly vocal during moonlit nights and in

the breeding season. Calls include various “weird, eerie shrieks and chuckles, in

addition to the loud bill-snapping” (Ali and Ripley 1983:256) denoting aggression

(Voous 1988).

Mottled Wood Owl (S. osce//eta)-The Mottled Wood Owl occurs on the Indian

subcontinent. Ali and Ripley (1983:256) described calls of S. o. oscellata as “a loud

quavering eerie chuhua-aa uttered regularly as the birds emerge from their daytime

retreat, and again before retiring at dawn [and] also from time to time during the

night, but not very frequently [see also Ali 19791. At other [nonbreeding] seasons

[calls are] mostly a single mellow, metallic hoot [and] an occasional harsh screech

similar to the Barn 0~1’s.” King and others (1975) listed the call as a loud, single

hoot. In northern India, I have heard it give an eerie descending, quavering whistle,

4 to 5 per minute; a rising, then falling, plaintive vibrato hoot, 20 per minute; and a

rather trilled, hooted series pdd-pddd-pdddd-pdd.

Hum&s Owl (S. butleri)-H-fume’s Owls are found mostly in the Middle East. The

Hume’s Owl has been considered by some to be a desert offshoot of the temperate

Tawny Owl (Voous 1988), but recent studies have not supported this hypothesis

(Hume and Boyer 1991). In most accounts it is given separate specific status (Voous

1988). Calls include “an unmistakable clear long-drawn huu uttered at intervals,

sometimes varied by a tremulous and more throaty hoot as in Strix aluco,” and

variants (Ali and Ripley 1983:255).

56
Ciccaba: Tropical

Cousins

Descriptions by Hume and Boyer (1991 :135) include the following. The call has been

reported to resemble that of the Tawny Owl and consists of a single long even note

that lacks the quavering typical of Tawny Owls. The call also has been described as

a “hoot followed by two shorter, double notes-hoooo huhu huhu.” Another call,

given in agitation, is hu-hu-hu-hu-hu-hu-hu, which lasts for 2 to 3 seconds. Two

birds have been heard calling in duet. In southern Israel, calls include a series of 12,

sometimes 13, notesgiven at dusk, the notes increasing slightly in speed and

noticably in volume. The final note in the series was lower and cut short and call

series “had a deep, slightly booming but rather muffled quality-bu bu bu bu bu bu

bu BU BU BU BU b”-and was unlike calls of the Tawny Owl.

Mikkola (1983) described calls of the Hume’s Owl as hoooo-huhu-huhu and

whoo-who-whoo, a longish hoot followed by two short double hoots. The birds

also give an excited and agitated hu-hu-hu-hu-hu-hu-hu lasting 2 to 3 seconds

when another bird is nearby or in response to taped calls.

Malay Wood Owl (S. orientalis)-The Malay Wood Owl occurs in southeast Asia.

Smythies (1984) described the calls of S. orientalis orientalis as commencing with

a rolling hoo-hoo-hoo and ending with a prolonged and deep drawn hoooo.

Spotted Wood Owl (S. se/oputo)-The Spotted Wood Owl is found in subtropical

and tropical parts of Southeast Asia. In some accounts, it is listed as a subspecies

of the Malay Wood Owl. King and others (1975) listed the Spotted Wood Owl in

Southeast Asia as S. selopufo (orientalis), whose varied calls include a deep rolling

hoo-hoo-hoo ending with a prolonged deep hooo’. Hume and Boyer (1991:137)

noted that its calls include a “series of low, musical notes that end with a longer,

deeper hoot.”

Although some authors (Norberg 1977, Voous 1964, 1988) have assigned the

mostly tropical wood owls of Ciccaba to the genus Strix, in this account I retain the

separate genera designations, following American Ornithologists’ Union (AOU) (1983).

Mottled Owl (C. virgata)-Mottled Owls occur in the New World tropics in Central

and South America. Their most common call is “2-3 successively louder grunts, low

and guttural, then 2 sharp downslurred hoots, the first louder: huh-huh; WHOO’,

WHOO;” and “sometimes a single hoot, or 1-3 grunts alone” (Stiles and Skutch 1989:

195). Hume and Boyer (1991) described other calls as a rising, whistling screech.

Stiles and Skutch (1989:195) defined it as “a long-drawn-out catlike screech usually

heard shortly after dusk or before dawn.” Peterson and Chalif (1973) described the

calls as “harsh and mournful waaa-a’-oooo, increasing then decreasing in pitch and

volume; a boo, boo-ab, boo-ab, boo-ab, boo-ab, boo-ab; a descending modulated

hoot; and a semi-whistled screech and a gruff growl” (Peterson and Chalif 1973).

Hilty and Brown (1986:231) described the most common call in Colombia as “a very

deep, resonant whooou, usually in pairs or triplets or sometimes 5-6 in a row,” and

that vocalizations also include, rarely, a catlike scream. Davis (1972) described the

most frequently heard calls as a 2-second series of five hoots cut off, as in hut,

the first two hoots spaced half a second apart and the others given at increasingly

shorter intervals. In Mexico, I have heard a Mottled Owl give a lo-second series

of short hut notes, first increasing, then decreasing, in pitch. Edwards (1972:91)

described the call as “a slow series of four or five, low-pitched, burred notes,

descending in pitch, hroot, hroot, hroot, hroot, hroot.”

57
Voous (1988) noted that Mottled Owls commonly interact vocally and territorially.

Their territorial song is “invariably described as a series of deep, often guttural and

slightly modulated hoots rendered as bru bru and bu bo bu (Panama; Wetmore

1968), keeooweeyo or cowooawoo (Panama, Ridgely 1981), or whoo-oo

(Venezuela; de Schauensee and Phelps 1978), all of the same character and quality

as the call of the Spotted Owl (Miller 1963)” (Voous 1988:203). Other calls of both

juveniles and adults include a long, drawn out, whistled screech, and a call sounding

like a child crying (Voous 1988). Immatures call with a catlike wail, louder and higher

pitched than the previously mentioned call and lasting about 1 second (Davis 1972).

Gerhardt (1991) reported five different vocalizations, including a three- to six-note

“hoot” given frequently by males and infrequently by females, the males in response

to taped calls and across home range boundaries. Females called at a higher pitch

than did the males. Another call given by adult females is used to solicit food from

the male, particularly near the nest, and is a “cat-like yowl” (Gerhardt 1991:23). A

third call is the food-begging call of juvenile mottled owls: a very soft “high-pitched

rattling hiss.” A fourth call is a growl given by adults during capture or when nest

trees were climbed. Another call is a peeping of the very young nestlings.

Black-and-White Owl (C. nigro/irteata)-Sometimes considered a subspecies of

C. huhula of South America (see below), this species is found from lowland, mostly

swampy forests in Central America and northwestern South America (Voous 1988).

Its call differs across its range (Hume and Boyer 1991). Its most common call is a

“low grunt followed by a gruff, strident hoot: huh, HOOoo; these sometimes followed

by 2 lower, softer, faster hoots, huh, HOOoo hoo-hoo, a 4-note call with pattern the

reverse of that of Mottled Owls.”

Young birds give an ascending, breathy shriek (Stiles and Skutch 1989:195). In La

Selva, Costa Rica, they give a low-pitched hooted series hu-hu-HU-HU-hu-hu, the

middle two notes higher in pitch and volume than the other notes (personal observation). Peterson and Chalif (1973) described calls as a loud, drawn out catlike

whee-u-u-u, and a resonant, low-pitched whoo, whoo, whoo. Edwards (1972:91)

described the voice as an “extended, slightly rasping, mewing sound.” Hume and

Boyer (1991:131) described the calls as “loud and high-pitched, like a long who-ah”;

in Panama, the call is a “long nasal oo-weh with a marked upward inflection, rather

quieter than the similar call of the Mottled Owl.”

Another more explosive, sharp sound is often repeated, sounding in Panama like a

deep, resonant and deliberate whoof, whoof, whoof; in Colombia, gives a strained,

rising and falling catlike scream, and a deeply resonant hu, hu, hu hoo-ah, and a

series of 9 to 14 hoo-ah notes with an occasional single deep boo (Hume and Boyer

1991). In Colombia, according to Hilty and Brown (1986:230-231), the species has

two very different calls: “a high-pitched dry scream, rising, then falling, catlike, and

strained as though only air is expelled (Hilty); and a deep, resonant, deliberate hu,

hu, hu, hoo-ah (last phrase slurred) with variations.” This last call also has been

described as “a series of 9-14 slow hu-wah’s and a single, loud, deep boo at

intervals” (P. Schwartz in Hilty and Brown 1986:231).

58
Discussion

Black-Banded Owl (C. h&u/a)-Black-Banded Owls generally are scarce

inhabitants of rain forests and plantations in northern and central South America.

Its voice is well described as a “rising cat-like scream followed by a loud hoot,

whoeeruh, hoo”, and also as a “deep, resonant hu hu hu HOOOO” (Hume and

Boyer 1991 :I 32). Hilty and Brown (1896:231, and P. Schwartz cited therein)

described the voice as “an ascending catlike scream, whoeeeruh followed after a

short pause by a loud booo; also a deliberate, deep, resonant hu, hu, hu, HOOO,

with variations.” The emphasized syllable is particularly forceful (personal observation

in Upper Amazon Basin, Ecuador). Hume and Boyer (1991) and Hilty and Brown

(1986) both noted that at times its voice is identical to that of the Black-and-White

Owl, and that they commonly respond to one another’s calls.

Rufous-Banded Owl (C. a/bitarsis)-This species occurs in Andean mountain

forests of South America. The species is said to greatly resemble the Fulvous Owl

(Kelso 1940) and is either an offshoot of the more northerly Strix or, less likely, is

a relict of a tropical form from which Strix arose (Voous 1988). In Colombia, it is

reported to give a deliberate pattern of deep, resonant notes, as in hu, hu-hu-hu,

HOOOa, repeated every 8 to 11 seconds (Hume and Boyer 1991). Hilty and Brown

(1986:231, and P. Schwartz cited therein) described it as “a deep, deliberate,

resonant hu, hu-hu-hu, HOOOa, repeated at 8-11 second intervals.” They also

noted that in Colombia, the main song of the Rufous-Banded Owl is similar to those

of the Black-Banded and Black-and-White Owls, but that it differs in cadence; the

Rufous-Banded Owl’s song includes a pause after the first note, the next three notes

are quicker, and the final note is more prolonged and more strongly given. Local

names of the Rufous-Banded Owl in Venezuela, including Borococo and Surrucuco,

resemble the calls (Hume and Boyer 1991).

African Wood Owl (C. woodfordii)-African Wood Owls (sometimes Strix

woodfordii, Newman 1991) are widespread and common in forests and open

woodlands of sub-Sahara Africa and the only Ciccaba found outside the Neotropics.

Descriptions of calls were given by Hume and Boyer (1991:133) as follows. Calls are

sometimes given in late afternoon from the top of the forest canopy. Both sexes give

a series of rapid hoots; the female’s are higher pitched. Calls begin “loudly and

evenly but fade away into an uneven rhythm-whu-whu-whu whu-uh uh-uh-uh.”

The female also gives a high wheeow which is answered by a low hoot from a

nearby male. The pair also will call together in a coordinated duet or in a series of

overlapping hoots. Newman (1991:216) described calls of males as “a rapid HU-hu,

hu-HU-hu-hu, hu-hu,” with females responding with a higher-pitched “hoo.”

Although vocalizations of every species of Strix and Ciccaba have not been studied,

several similarities are evident from reports cited herein. Vocalizations of most Sfrix

species include location calls. These calls typically consist of a series of four or

more hooted notes such as given by Spotted, Barred, Great Gray, Brown Wood,

Himalayan Brown Wood, and Fulvous Owls. Other similarities among Sfrix species

include various screeched, wailed, or barking calls such as given by Spotted, Barred,

Tawny, Ural, and Brown Wood Owls. Still other species give extended wavering

notes or single loud hoots, as with Hume’s and Mottled Wood Owls. Malay Wood

and Spotted Wood Owls give a long rolling series of hoots. Ciccaba vocalizations

include four- or five-note location type calls and variations on rolling and downwardslurred notes, similar in description to those of their Sfrix relatives.

59
Literature Cited

Degree of similarity in vocalizations can be one piece of evidence for degree of

evolutionary relatedness. For example, in forests of the Pacific Northwest United

States, hybrids of Spotted and Barred Owls (nicknamed “sparred owls”) have been

observed giving vocalizations intermediate between the two species.’ It has been

only in recent years that the two species have become sympatric with the Barred

Owl invading the range of the Spotted Owl’s (Boxall and Stepney 1982, Hamer

1985, Taylor and Forsman 1976). In Europe, Tawny and Ural Owls, a similar pair

of closely related species, have hybridized in captivity (Scherzinger 1983, Voous

1988), with the fertile hybrids having a similar but “more varied vocabulary” than

either parent. Also, van der Weyden (1972) demonstrated the close relatedness

between the Tawny Owl and the Afrotropical Wood Owl (Ciccaba woodfordii,

sometimes placed in Strix, as with Voous 1988) based on similarity of vocalizations

of owls in Morocco and Senegal, West Africa. Understanding degree of relatedness

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habitat requirements and evolutionary history of closely related species.

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63
Appendix B: Species and selected subspecies mentioned in the appendix text

Species and

Selected Subspecies GFtg gli Nearctic RegionSpotted Owl (S. occidentalis)

Northern Spotted Owl (S. o. caurina)

Barred Owl (S. varia)

Great Gray Owl (S. nebulosa)

Strix of the Neotropical RegionFulvous or Guatemala Barred Owl (S. fulvescens)

Rusty-Barred Owl (S. hylophila)

Rufous-Legged Owl (S. rufipes)

Strix of the Palearctic and Oriental RegionsTawny Owl (S. &co)

Scully’s Wood Owl (23. a. biddu/ph/)

Himalayan Wood Owl (S. a. nivicola)

Ural Owl (S. uralensis)

David’s Wood Owl (S. u. cfavido (sometimes considered as the separate species

S. david)

Brown Wood Owl (S. leptogrammica)

Himalayan Brown Wood Owl (S. 1 . newarensis)

Brown Wood Owl (Burma) (S. 1 . indranee)

Mottled Wood Owl (S. oscellata)

Mottled Wood Owl (India) (S. o. oscellata)

Hume’s Owl (S. butler/)

Malay Wood Owl (S. orientalis)

Malay Wood Owl (S. o. orientalis)

Spotted Wood Owl (S. seloputo (orientalis)) (often combined with Malay Wood

Owl)

Genus Ciccaba:

Ciccaba of the Neotropical RegionMottled Wood Owl (C. virgata)

Black-and-White Owl (C. nigrolineata) (sometimes considered a subspecies of

C. huhula)

Black-Banded Owl (C. huhula)

Rufous-Banded Owl (C. albitarsis)

Ciccaba of the Palearctic RegionAfrican Wood Owl (C. woodfordil)

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