HABITAT SUITABILITY INDEX MODELS:

LEWIS· WOODPECKER

SK

361

.U54

no. 82-

10.32

hand Witdlife Service

. Department of the Interior
Thi s model is designed to be used by the Division of Ecological Servi~es

i n conjunction with the Habitat Evaluation Procedures.
FWS/OBS-82/10.32

April 1983

HABITAT SUITABILITY INDEX MODELS: LEWIS' WOODPECKER

by

Patrick J. Sousa

Habitat Evaluation Procedures Group

Western Energy and Land Use Team

U.S. Fish and Wildlife Service

Drake Creekside Building One

2627 Redwing Road

Fort Collins, CO 80526

Western Energy and Land Use Team

Division of Biological Services

Research and Development

Fish and Wildlife Service

U.S. Department of the Interior

Washington, DC 20240
This report should be cited as:

Sousa, P. J. 1982. Habitat suitability index models: Lewis' woodpecker.

U.S. Dept. Int., Fish Wildl. Servo FWS/OBS-82/10.32. 14 pp.
PREFACE

This document is part of the Habitat Suitability Index (HSI) Model Series

(FWS/OBS-82/10), which provides habitat information useful for impact assessment and habitat management. Several types of habitat i nformat i on are

provided. The Habitat Use Information Section is largely constrained to those

data that can be used to derive quantitative relationships between key environmental variables and habitat suitability. The habitat use information provides

the foundation for HSI models that follow. In addition, this same information

may be useful in the development of other models more appropriate to specific

assessment or evaluation needs.

The HSI Model Section documents a habitat model and information pertinent

to its application. The model synthesizes the habitat use information into a

framework appropriate for field application and is scaled to produce an index

value between 0.0 (unsuitable habitat) and 1.0 (optimum habitat). The applicat ion i nformat ion i ncl udes descri pt ions of the geographi c ranges and seasona 1

application of the model, its current verification status, and a listing of

model variables with recommended measurement techniques for each variable.

In essence, the model presented herein is a hypothesis of species-habitat

relationships and not a statement of proven cause and effect relationships.

Results of model performance tests, when available, are referenced. However,

models that have demonstrated reliability in specific situations may prove

unreliable in others. For this reason, feedback is encouraged from users of

this model concerning improvements and other suggestions that may increase the

utility and effectiveness of this habitat-based approach to fish and wildlife

planning. Please send suggestions to:

Habitat Evaluation Procedures Group

Western Energy and Land Use Team

U.S. Fish and Wildlife Service

2627 Redwing Road

Ft. Collins, CO 80526

iii

CONTENTS

PREFACE iii

ACKNOWLEDGMENTS vi

HABITAT USE INFORMATION 1

Genera 1 1

Food 1

Water 2

Cover 2

Reproduct ion 2

I nterspersi on 3

Special Considerations............................................ 3

HABITAT SUITABILITY INDEX (HSI) MODEL , '" 4

Model Applicability............................................... 4

Model Description................................................. 5

Model Relationships............................................... 8

Application of the Model.......................................... 11

SOURCES OF OTHER MODELS 13

REFERENCES 13

v
ACKNOWLEDGMENTS

Dr. Carl E. Bock provided valuable critiques of earlier drafts of an HSI

model for the Lewis' woodpecker. His comments and suggestions added significantly to the quality of this model, and his contributions are gratefully

acknowledged.

Word processing of this document was provided by Carolyn Gulzow and

Dora Ibarra. The cover was illustrated by Jennifer Shoemaker.

Publication costs of this model were partially paid for by the U.S. Army

Corps of Engineers.

vi
LEWIS' WOODPECKER (Melanerpes lewis)

HABITAT USE INFORMATION

General

The Lewis' woodpecker (Melanerpes lewis) inhabits open forest stands and

feeds primarily on insects from spring to fall and on mast crops during the

winter (Bock 1970). It occurs regularly in Western North America ..... from

eastern Colorado west to the Pacific, and from British Columbia to northernmost

Mexico" (Bock 1970:80). The species may be a year-round resident in suitable

habitats (Bock et al. 1971).

Food

The Lewis' woodpecker is an opportunistic feeder that breeds where insects

are locally abundant and winters where abundant mast crops are available (Snow

1940; Bock 1970). The selection of some habitats for breeding and rejection

of others probably reflects differences in insect abundance. The diet may

also include various fruits, berries, and seeds in late summer. The Lewis'

woodpecker may stockpile food in cracks and holes near the nest site (Constantz

1974), and breeding adults may store insects in cracks for later feeding to

the nestlings (Bock 1970).

In contrast to most other woodpeckers, the Lewis' spends more time flycatchi ng and ground-brush foragi ng than probi ng for insects (Bock 1970). A

breeding population in a pine (Pinus spp.) forest in California spent 60% of

thei r feedi ng time flycatchi ng, 30% ground-brush foragi ng, and 10% gl eani ng

insects from tree surfaces. A breeding population in an oak (Quercus spp.)

woodland spent relatively similar amounts of time in the above activities, but

also spent 11% of their feeding time utilizing previously stored acorns.

Lewi sI woodpeckers breedi ng -jn ri pari an cottonwood (Popul us spp.) groves and

farmland cottonwood fence rows in southeastern Colorado fed largely by

flycatching over adjacent grazed pastures or plowed fields (Bock, pers. comm.).

There is no evidence that chiseling, typical of most woodpeckers, is ever used

as a foraging technique by the Lewis' woodpecker (Bock 1970).

Lewis' woodpeckers winter in areas of abundant mast, such as oak woodlands

or commercial nut orchards, especially almonds and walnuts (Bock 1970), or

adjacent to corn fields (Bock et al. 1971; Hadow 1973). Acorns formed a major

portion of the diet of the Lewis' woodpecker from September through April in

Utah (Snow 1940). Individuals (rarely a pair) collect and store mast in

natural crevices, such as cracks in trees or utility poles (Snow 1940; Bock

1970). Within oak woodlands, areas with a diversity of oak species probably

provide a more dependable mast supply than oak woodlands dominated by a single

species. However, mast diversity in any specific area may not be critical to

winter survival because the Lewis' woodpecker is highly opportunistic and will

1
move to areas of high mast availability (Bock, pers. comm.). Winter caches

are defended both against inter- and intraspecific competitors (Snow 1940;

Hadow 1973). A wintering population in a California oak woodland spent about

72% of their feeding activities harvesting and storing mast, 15% flycatching,

and 13% gleaning insects from tree trunks (Bock 1970). Despite the large

amount of time invested in collecting, storing, and defending mast supplies,

Hadow (1973) suggested that insects are preferred in winter whenever they are

available and that the mast stores serve as reserve food supplies.

Flycatching activities (hawking) start from prominent perches, including

stumps, fenceposts, utility poles, and tall trees (Bock 1970). When groundbrush scanning, Lewis' woodpeckers scan their surroundings from low perches,

such as stumps or shrubs.

Water

No information regarding water requirements for the Lewis' woodpecker was

found in the literature.

Cover

Habitats used by Lewis' woodpeckers are characterized by their openness

(Bock 1970). Open forests allow sufficient vi sibi 1ity and movement for the

Lewis· woodpecker to flycatch effectively and also allow the development of a

shrubby understory that supports terrestrial insects. Vertical interspersion

of vegetative strata is important in evergreen forests and in burns in meeting

habitat requirements for breeding and, to a lesser degree, for winter habitat.

Although logged or burned habitats may provide suitable habitat for 10 to 30

years following the disturbance, the habitat will be unsuitable if it does not

contain a shrub stratum (as a result, for example, of overgrazing or intensive

forest management). However, the presence of a shrubby understory is appa rently of less importance in riparian groves, farmstead fence rows, and oak

woodlands (Bock, pers. comm.). Although the reasons for such a difference in

the importance of shrubs is unclear, it may be due to different feeding

strategies in coniferous and burned habitats compared to riparian and oak

habitats.

Scanning perches are an important, but not usually limiting, component of

year-round habitat (Bock 1970).

Reproduction

The Lewis' woodpecker is restricted, as a breeding species, to areas

be low the upper montane 1i fe zone (Bock, pers. comm.). Park1ike ponderosa

pine (Pinus ponderosa) stands provide the major breeding habitat of the Lewis'

woodpecker throughout its range (Bock 1970). The combination of an open

canopy, a brushy understory, and an abundance of insects describes breeding

habitat for the Lewis' woodpecker in ponderosa pine forests. Logged or burned

coniferous forests that are structurally similar to parklike pine stands also

provide suitable breeding habitat. At lower elevations, breeding habitat is

provided by riparian cottonwood groves, fence rows in agricultural areas, and

oak woodlands (Bock, pe\s. comm.). Suitable conditions for breeding in these

2
habitats are provided by the same structural features important in ponderosa

pine forests, except that shrub cover is apparently not a critical habitat

feature. Areas domi nated by agri cul tura 1 1ands may be used by Lewi s ' woodpeckers if sufficient nest trees are available in fence rows, along roads, or

around buildings (Bock et al. 1971). Pinyon-juniper (Pinus edulis-Juniperus

spp.) woodlands are infrequently occupied, possibly because such woodlands

typically occur on dry sites that may not support sufficient insect prey (Bock

1970).

Lewis' woodpeckers are cavity nesters but are not well suited for

excavating their own cavities except in dead or dying trees (Bock 1970). The

height of nest cavities summarized by Bock (1970) ranged from 1.5 to 51.8 m (5

to 170 ft), although Thomas et al. (1979a) considered the minimum snag height

to be 9.1 m (30 ft). Suitable snags have a minimum diameter at breast height

of 30.5 cm (12 inches) (Thomas et al. 1979a). An average density of one

suitable snag per 0.4 ha (1 acre) is required to support maximum breeding

densities of Lewis' woodpeckers in the Blue Mountains of Washington and Oregon

(Thomas et al. 1979a). The proportion of the maximum population that can be

supported is considered to be positively correlated with snag density; for

example, in otherwise equal habitat, an area with an average density of only

0.5 snags per 0.4 ha (1.0 acre) will support only 50% of the maximum breeding

population.

Cavity nesters genera lly face a shortage of nesting sites where trees

occur in clumps (Jackman 1975). In areas of high demand for sites, Lewis'

woodpeckers may nest wi thi n a short di stance of each other. Curri er (1928)

reported three holes that were occupied by Lewis' woodpeckers in each of two

trees less than 0.4 km (0.25 mi) apart. Managed forests generally have fewer

available nesting sites than do natural forests, because snags and diseased

and damaged trees are usually removed (Jackman 1975). Lewi s ' woodpeckers

exhibit a strong pair bond and high nest fidelity, returning to nest in the

same cavity in consecutive years (Bock 1970).

Interspersion

Bock (1970) reported that Lewi sI woodpeckers defend only the i mmedi ate

area around the nest site and, in winter, around the stored food (Bock 1970).

In contrast, a territory size of 6.1 ha (15 acres) per pair has been reported

in the Blue Mountains of Washington and Oregon (Thomas et al. 1979b). Spacing

of individuals on wintering grounds is probably determined by food or storage

site availability and competition (Hadow 1973). l.ewts ' woodpeckers in Utah

moved 0.6 to 0.9 km (1 to 1.5 mi) from winter habitat to nesting habitat (Snow

1940) .

Special Considerations

Although preferred habitat types for breeding and wintering remain structurally similar from year to year, the presence of Lewis· woodpeckers in any

given preferred habitat depends heavily on the food supply, either insects or

mast (Bock 1970). Because the habitat needs of Lewi s ' woodpeckers are more

specialized in winter than during the breeding season, destruction of winter

3
range represents a greater potential threat to the species than loss of breeding habitat (Bock, pers. comm.).

Lewis' woodpecker habitat may be adversely affected by grazing, if it

eliminates brushy undergrowth, or by forestry practices that eliminate snags

or a brushy understory (Jackman 1975). Forest management pract ices that

provide snags, a brushy understory, and slash provide suitable Lewis' woodpecker habi tat.

The Lewis' woodpecker has been included in the Audubon Society's Blue

List since 1975 (Tate 1981). The list is intended as an early warning list of

species exhibiting noncyclical population declines or range contractions.

Competition for nest sites from starlings (Sturnus vulgaris) may be a possible

cause of the decline. However, evidence also exists that the Lewis· woodpecker

has expanded its range into plains habitat in response to maturation of cottonwoods around rura 1 residences and the avail abi 1i ty of a mast source in the

form of irri gated corn (Hadow 1973). The Lewi s ' woodpecker is cons i dered a

potential sensitive environmental indicator in forest communities dominated by

ponderosa pine (Diem and Zeveloff 1980).

Lewis' woodpeckers can apparently do considerable damage to commercial

nut orchards during fall and winter (Neff 1926). Large flocks in late summer

may damage fruit orchards (Jackman 1975).

HABITAT SUITABILITY INDEX (HSI) MODEL

Model Applicability

Geographic area. This HSI model was developed for use within the breeding

and wintering range of the Lewis' woodpecker.

Season. This model was developed to obtain an HSI for breeding habitat

and/or winter habitat used by the Lewis· woodpecker.

Cover types. The Lewis' woodpecker is associated with open forest stands

during the breeding season and may use any of the following cover types (terminology follows that of U.S. Fish and Wildlife Service 1981): Evergreen

Forest (EF); Deciduous Forest (OF); Evergreen Tree Savanna (ETS); Deciduous

Tree Savanna (DTS); Desertic Woodland (OW); Deciduous Forested Wetland (DFW);

and Cropland (C). For purposes of this model, Evergreen Forest and Evergreen

Tree Savanna are considered to represent only those stands dominated by ponderosa pine; evergreen cover types dominated by other species should not be

evaluated with this model. Cover types classified as any of the deciduous

types (OF, DTS, OW, DFW) are considered to represent only those sites dominated

by either cottonwoods or oaks; deciduous types dominated by other species

should not be evaluated with this model. Only those croplands in corn production should be evaluated with this model.

4
Minimum habitat area. Minimum habitat area is defined as the minimum

amount Df contiguous suitable habita~ that is required before an area will be

occupied by a species. A territory size of 6.1 ha (15 acres) per pair of

Lewis' woodpeckers has been reported from Washington and Oregon (Thomas et al.

1979b), although other sources report that a defended territory is maintained

only in the vicinity of a nest or winter food cache (Bock 1970). Lewis'

woodpeckers will also breed and winter in relatively small areas of fence rows

and riparian woodlands (Bock, pers. comm.). Adjacent open cover types are

used in such instances for foraging. Because of the opportunistic nature of

the Lewis' woodpecker, no minimum habitat area is defined in this model. If a

habitat is large enough to be mapped as any of the cover types listed above,

it is assumed that enough area of the cover type will be available in most

instances to provide potential habitat for the Lewis' woodpecker.

Verification level. Two earlier drafts of an HSI model for the Lewis'

woodpecker were reviewed by Dr. Carl E. Bock. His review comments have been

incorporated into this model.

Model Description

Overview. The distinguishing characteristic of breeding habitat of the

Lewis' woodpecker is openness of the tree canopy, although sufficient trees

must be available to provide nest sites. Food and reproductive needs are

considered to be the most important life requisites for the Lewis' woodpecker

during the breeding season. Cover requirements during the breeding season are

assumed to be met by the same set of habitat characteristics that define

reproductive habitat. Food is considered to be the most important life

requisite during winter. Winter cover needs are assumed to be met by the same

set of habitat characteristics that define winter food. Water is not considered limiting to the Lewis' woodpecker during any season.

The following sections identify important habitat variables, describe

suitability levels of the variables, and describe the relationships between

variables. The relationship between habitat variables, life requisites, and

cover types used in this model and an HSI value for the Lewis' woodpecker is

shown in Figure 1.

Summer food component. In contrast to typical woodpecker foraging

methods, Lewis' woodpeckers rarely use chiseling as a foraging technique. The

most common foraging method during the breeding season is flycatching, which

requires open scanning perches such as stumps, trees, or fence posts. Other

commonly used foraging methods include foraging on the ground or shrubs, and

gleaning. Lewis' woodpeckers also feed heavily on fruits and berries during

late summer and fall.

A1though the occurrence of the Lewi s ' woodpecker in any specifi c area

during the summer may be sporadic due to available food, characteristics of

preferred habitat can be used to determine the habitat potential of a selected

cover type. Preferred foraging habitat during the breeding season in ponderosa

pine stands (including logged or burned ponderosa pine stands) is characterized

by an open canopy and a dense understory. The open canopy allows sufficient

vision and mobility for the Lewis' woodpecker to forage by flycatching and a

5
Habitat variable

Life

requisite Season Cover types

-----HSI

Deciduous Forest

Evergreen Tree

Savanna

Deciduous Tree

Savanna

Desertic Woodland

Deciduous Forested

Wetland

Wi nte r food Wi nte r

Percent tree canopy closur~

Summer

Percent shrub crown cover food

> Summer... Evergreen Forest HSI

Number of snags greater than or equal to 30.5~mReproduction (12 inches) dbh per

0.4 ha (1 acre)

Percent crown cover of

mast-producing shrubs

Percent of the total tree

canopy closure that is

hard mast-producing trees

0)

Cropland management practice

-------- Winter food Winter Cropland HSI

Distance to nearest potential

mast storage sites

Figure 1. Relationship of habitat variables, life requisites, seasonal habitat,

and cover types in the Lewis' woodpecker HSI model.
dense understory provides habitat for numerous insect prey for ground or brush

foraging. In this model, it is assumed that canopy conditions will be optimal

if tree canopy closure is 1ess than 30% and will be unsuitab1 e if canopy

closure exceeds 75%. Optimal understory conditions are assumed to exist if

shrub crown cover exceeds 50%. Both understory and canopy conditions must be

optimal in order to have optimal conditions in ponderosa pine stands. If tree

canopy closure exceeds 75%, or if no shrubs occur in the understory, then it

is assumed that the habitat will not be useable by the Lewis' woodpecker. The

same habitat features may be used to describe foraging habitat during the

breeding season in deciduous cover types, although a dense shrub stratum is

apparently unnecessary. In deciduous cover types, the presence of shrubs is

considered to add to the food value, but will not be limiting to food

sui tabi 1ity.

Winter food component. The winter diet of the Lewis· woodpecker consists

primarily of available acorn mast or corn. Mast is stored in caches and is

occasionally used early in the breeding season. It is assumed that evergreen

forests do not usually provide adequate mast, although evergreen tree savannas

may provide adequate mast in the form of Gambe1's oak (Quercus gambe1ii).

Potent i a 1 mast production in nonagri cultura1 types can be eva 1uated by the

amount of mast producing species present in the shrub and tree strata. It is

assumed that potential mast production (and winter food suitability) in the

shrub stratum increases with increased canopy cover of mast-producing shrubs.

Although the same reasoning would appear to hold true for the tree stratum,

the Lewis' woodpecker prefers open woodlands. It is assumed in this model

that optimal conditions will be approached as the proportion of mast-producing

species in the tree canopy increases. Optimal tree canopy conditions are

assumed to be the same as described previously under the summer food component.

Tota 1 food needs may be met by mast from ei ther the shrub or tree strata or

from a combination of both food sources.

Corn is assumed to be the only crop that provides a suitable winter mast

source for Lewis' woodpeckers. The suitability of cornfields is a function of

the abundance of corn during winter and the availability of mast storage

sites. Corn that is 1eft standi ng throughout the wi nter wi 11 provi de an

abundant mast supply. Cornfi e 1ds that are harvested in the fa 11 but have

stubble plowed under in the spring are assumed to provide a moderate amount of

waste grain throughout the winter. Cornfields that are harvested and fall

plowed are assumed to provide only minimal quantities of mast for Lewis'

woodpeckers. Lewis' woodpeckers require mast storage sites in the form of

trees or utility poles with desiccation cracks. It is assumed in this model

that mast sources within 0.8 km (0.5 mi) of potential storage sites will be

optimally available. Mast sources located more than 1.6 km (1 mi) from storage

sites are considered unavailable to Lewis' woodpeckers. The suitability of

mast abundance is modified by the suitability of mast storage sites to obtain

an overall winter food value for croplands.

Reproductive component. Lewts ' woodpeckers are cavity nesters, but are

not well suited for excavation except in dead or dying trees. The presence of

dead or dying trees, or existing cavities, is a critical component of breeding

habitat. Suitable snags are characterized by a minimum diameter at breast

height of 30.5 cm (12.inches) and a minimum height of 9.1 m (30 ft). An

7
average of at least one snag per 0.4 ha (l acre) is considered adequate to

support maximum breeding densities of Lewis' woodpeckers. The proportion of

the maximum population that can be supported by specific habitat conditions is

positively correlated with snag density.

Model Relationships

Suitability Index (SI) graphs for habitat variables. This section

contains suitability index graphs that illustrate the habitat relationships

described in the previous section.

Cover

EF,DF,

ETS,DTS,

DW,DFW

Variable

Percent tree canopy

closure.

1.0

x 0.8 OJ

-0

c:

.......

0.6

..0 0.4 n::l

+.>

0.2 (/)

25 50

%

75 100

EF,DF, Vz Percent shrub crown 1.0

ETS,DTS, cover.

DW,DFW x

OJ 0.8

-0

c:

.......

>., 0.6

-+J

r-

..0 0.4 n::l

-+J

(/) 0.2

8

25 50

%

75 100
DF,ETS,

V3 Percent crown cover 1.0

DTS,OW, of hard mastOFW producing shrubs.

x

(]) 0.8

"'0

s::

.......

0.6

''-

r-

''-

...Q 0.4 ttl

+J

:::J

Vl 0.2

OF,ETS,V4 Percent of the total 1.0

DTS,DW, tree canopy closure

x DFW that is hard mast- (]) 0.8

producing trees. "'0

s::

.......

0;6

''-

r-

''-

...Q 0.4 ttl

+J

''-

:::J 0.2 Vl

%

I

CVs Cropland management 1.0

practice.

x

(]) 0.8

A. Corn left stand- "'0

s::

ing throughout .......

winter. >, 0.6 +J

B. Corn harvested in ''-

fall, stubble ''-

...Q 0.4

plowed under in ttl

+J

spring. ''-

:::J 0.2 C. Corn harvested Vl

and stubble

plowed under

in fall.

9

A

25 50%B

75

c

100
c V6 Distance to nearest 1.0

potential mast x

storage site -(trees, <Ll 0.8 -0 wooden utili ty poles). t::

......

0.6 'r-

'r-

...0 0.4 ra

.jJ

'r-

:::s

l/) 0.2

0.4

0.25

0.8

0.5

1.2

0.75

1. 6 (km)

1.0 (mi)

EF,DF,

ETS,DTS,

DW,DFW

Number of snags

30.5 cm (12 inches)

dbh per 0.4 ha

(l acre).

1.0

x

<Ll 0.8

-0

t::

......

>, 0.6 .jJ

'rr-

'r-

...0 0.4 ra

.jJ

:::s

l/) 0.2

0.25 0.50 0.75 1.0+

Equations. In order to obtain life requisite values for the Lewis'

woodpecker, the SI values for appropriate variables must be combined through

the use of equations. A discussion and explanation of the assumed relationships between variables was included under Model Description, and the specific

equations in this model were chosen to mimic these perceived biological relationships as closely as possible. The suggested equations for obtaining life

requisite values are presented in Figure 2.

10
Life requisite Cover types Equation

Summer food EF, ETS (V 1 x V2 ) 112

Summer food DF,DTS, Vi + V2

DW,DFW

(N.B. If Vi =0, the summer

food value equals 0.0. If the

sum of Vi and V2 exceeds 1.0,

the summer food value equals 1.0.)

Winter food

Winter food

Reproduction

DF,ETS,

DTS,DW,

DFW

C

EF,DF,

ETS,DTS,

DW,DFW

1/2

V3 + (V 4 x Vi)

(N.B. If the sum exceeds 1.0,

the winter food value equals

1. 0.)

Figure 2. Equations for determining life requisite values

by cover type for the Lewis' woodpecker.

HSI determination. Because the Lewis' woodpecker is opportunistic in

both summer (breeding) and winter habitat selection, a cover type may be

useful at one time of year without necessarily meeting year-round habitat

needs. In those types that provide summer habitat (EF, OF, ETS, DTS, OW,

DFW), the summer habitat value is the lowest of the summer food and reproduction life requisites. Winter habitat value in all types, except evergreen

forests (i .e., ETS, OF, DTS, OW, DFW, C), equals the winter food value determi ned for the cover type. The HSI va1ue in those cover types potentially

providing year-round habitat (i.e., ETS, OF, DTS, OW, DFW) is equal to the

highest of the values for summer habitat and winter habitat. The HSI equals

the summer habitat value in evergreen forests and the winter habitat value in

croplands. The relationship of the HSI value by cover type to habitat variables and seasonal needs is presented in Figure 1 (p. 6).

Application of the Model

Definitions of variables and suggested field measurement techniques (Hays

et al. 1981) are provided in Figure 3.

11
Variable (Definition)

Percent tree canopy

closure [the percent

of the ground that is

shaded by a vertical

projection of the

canopies of woody

vegetation greater

than 5 m (16.5 ft)

in height].

Percent shrub crown

cover [the percent of

the ground that is

shaded by a vertical

projection of the

canopies of woody

vegetation less than

5 m (16.5 ft) in

height].

Percent crown cover of

hard mast-producing

shrubs [the percent

of the ground that is

shaded by a vertical

projection of the

canopies of woody

vegetation less than

5 m (16.5 ft) in

height that produce

hard mast, such as

acorns (e.g., Gambel's

oak)].

Percent of the total

tree canopy closure

that is hard mastproducing trees (the

proportion of the

estimate for VI that

is made up of trees

producing hard mast,

such as acorns,

walnuts, or almonds).

Cover types

EF,DF,ETS,DTS,

DW,DFW

EF,DF,ETS,DTS,

DW,DFW

ETS,DF,DTS,

DW,DFW

ETS,DF,DTS,

DW,DFW

Suggested technique

Transect, line intercept,

remote sensing

Line intercept, quadrat,

remote sensing

Line intercept, quadrat,

remote sensing

Transect, line intercept,

remote sensing

Figure 3. Definitions of variables and suggested measurement techniques.

12
Variable (Definition)

Cropland management

practice (an evaluation

of the winter availability of corn based

on management of corn

crops. Management

categori es are: corn

left standing, spring

plowing, and fall

plowing).

Distance to nearest

potential mast

storage site (an

evaluation of the

ava il abil i ty of

trees or wooden

utility poles for

storage of corn

mast in winter

caches).

Number of snags 30.5 cm

(12 inches) dbh per 0.4 ha

(1 acre) [the number of

standing dead trees or

partly dead trees

at least 30.5 cm

(12 inches) dbh

and at least 9.1 m

(30 ft) tall].

Cover types

C

C

EF,DF,ETS,DTS,

DW,DFW

Suggested technique

On-site inspection

Remote sensing, ruler

Quadrat

Figure 3. (concluded).

SOURCES OF OTHER MODELS

No other habitat models for the Lewis' woodpecker were located.

REFERENCES

Bock, C. E. 1970. The ecology and behavior of the Lewis woodpecker

(Asyndesmus lewis). Univ. Calif. Publ. Zool. 91. 100 pp.

13
Personal communication (letters dated 5 March 1982 and 2 August

1982). Dept. Environmental, Population, and Organismic Biology, Univ.

Colorado, Boulder.

Bock, C. E., H. H. Hadow, and P. Somers. 1971.

red-headed woodpeckers in southeastern

83(3):237-248.

Relations between Lewis' and

Colorado. Wilson Bull.

Constantz, G. D. 1974. Robbing of breeding l.ewt s ' woodpecker food stores.

Auk 91(1):171.

Currier, E. S.

30(6):356.

1928. Lewis' woodpeckers nesting in colonies. Condor

Diem, K. L., and S. 1. Zeveloff. 1980. Ponderosa pine bird communities.

Pages 170-194 in R. M. DeGraff and N. G. Tilghman (compilers). Workshop

Proceedi ngs: Management of western forests and grasslands for nongame

birds. U.S. Dept. Agric., For. Servo Gen. Tech. Rep. INT-86. 535 pp.

Hadow, H. H. 1973. Winter ecology of migrant and resident Lewis' woodpeckers

in southeastern Colorado. Condor 75:210-224.

Hays, R. L., C. Summers, and W. Seitz. 1981. Estimating wildlife habitat

variables. U.S. Dept. Int., Fish Wildl. Servo FWS/OBS-81/47. 111 pp.

Jackman, S. M. 1975. Woodpeckers of the Pacific Northwest: Their characteristics and their role in the forests. M.S. Thesis, Oregon State Univ.,

Corvallis. 147 pp.

Neff, J. A. 1926. A study of the economic status of the common woodpeckers

in relation to Oregon horticulture. M.S. Thesis, Oregon State Agric.

Coll., Corvallis. 133 pp.

Snow, R. B. 1940. A natural history of the Lewis woodpecker, Asyndesmus

Lewis (Gray). M.S. Thesis, Univ. Utah. 75 pp.

Tate, J., Jr. 1981. The Blue List for 1981. Am. Birds 35(1):3-10.

Thomas, J. W., R. G. Anderson, C. Maser, and E. L. Bull. 1979a. Snags.

Pages 60-77 in J. W. Thomas, tech. ed. Wildlife habitats in managed

forests: the-Slue Mountains of Oregon and Washington. U.S. Dept. Agric.,

For. Servo Agric. Handbook 553. 512 pp.

Thomas, J. W., R. W. Miller, C. Maser, R. G. Anderson, and B. E. Carter.

1979b. Pl ant commun iti es and successi ona 1 stages. Pages 22-39 .in J. W.

Thomas, tech. ed. Wildlife habitats in managed forests: the Blue

Mountains of Oregon and Washington. U.S. Dept. Agric., For. Servo Agric.

Handbook 553. 512 pp.

U.S. Fish and Wildlife Service. 1981.

Habitat Suitability Index models.

Wildl. Serv., Div. Ecol. Servo n.p.

14

Standards for the development of

103 ESM. U.S. Dept. Int., Fish.
50272 -ret

REPORT DOCUMENTATION !.l... AEPORT NO.

PAGE : FWS/OBS-82/10.32

'2.

I

I 3. AeciDienc's Acceesion No.

i

, TItle _nd Subtitle

Habitat Suitability Index Models: Lewis' Woodpecker I

5. AellOl't O.te

Apri 1 1983

I.

7. -.utllor(s) a. ,..rlorminl O....nizetlon Aeot. No.

I"atrl ck J. Sousa

f------------..---------.-------------+-------------~

9. Perlarminl O....niz.tion N.me _nd Addr... Habi tat Eval uation Procedures Group

Western Energy and Land Use Team

U.S. Fish and Wildlife Service

Drake Creekside Building One

2627 Redwing Road

Fort Collins, CO 80526

10. Projec:t/Tuk/Worlc Unit No.

11. CGntrac:t(C) ar Gnlnt(Gl No.

(C)

(G)

12. Soon,orinlOrpniutton N.me _nd Add..... -Western -r-nergy and Land Use 1earn

Division of Biological Services

Research and Development Fish and Wildlife Service

Washington, DC 20240

I 13. TYDe at AeDQrt & Period C4vered

I

14.

15. SUDDlement.ry Not..

·11. AlIstr.ct (Wmit: 200 ward.,

Habitat preferences of Lewis' woodpecker (Melanerpes lewis) are described in

this publication, which is one of a series of Habitat Suitability Index (HSI)

models. A re~iew and synthesis of the literature is followed by development

of a model of the species-habitat requirements of Lewis' woodpecker. Habitat

suitability indexes are designed for use with Habitat Evaluation Procedures

previously developed by the U.S. Fish and Wildlife Service.

17. Oocument An.lyei. _. Oescriptors

Mathematical models, Wildlife, Habitability, Birds.

tl. identitiers/Ooen·Endec:l Term,

Lewis' woodpecker

Melanerpes lewis

Habitat Suitability Indexes (HSI)

c. COSATI Field/GroUl!

• ....\I.,l.bility St.tement Release Unlimited 21. No. of lOsIe.

14

20. Security Crass (This IOseel

UNCLASSIFIED

,5" ANSI-Z39.1Sl See Instructions on "'s"erse

1< us, GOVERNMENT PRINTING OFFICE: 1983---679-525/300 REGION NO.8

OPTIONAL FORM 272 (oI-i1)

(Formerly NTI5-3Sl

Cell.rtment of Commerce
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VlrQln ISlan<1S

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Habi tat suitabi lity index Ilodels : 2494 7

Sousa, Patrick J. S~361 .U56 no.82

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• Locations 0' RegIOnal Offices

• 'NeSlern Energy ana Lana Use Team

FI Courns CO

.... HawaIIan Island P

t:l H ac::!~ua·1ers DIYISlon of BIologic al

Ser... ces Washington DC

)( East ern Energy and Land Use Team

L.eeiown WV

* aucnat Coas tai Ecosystems Team

suceu LA

REGION 2

Regional Director

U.S. Fish and Wildlife Service

P.O. Box 1306

Albuquerque. New Mexico 87103

REGION 3

Regional Director

U.s. Fish and Wildlife Service

Federal Building. Fort Snelling

Twin Cities, Minn~sotll 55111

REGION 4

Relional Director

U.S. Fish and Wildlife Service

Richard B. Russell Building

75 Spring Street. S.W.

Atlanta. Georgia 30303

REGION S

Regional Director

U.S. Fish and Wildlife Servrce

One GatewayCenter

Newton Corner, MassachulCtts 02158

REGION 6

Regional Director

U.S. Fish and Wildlife Service

P.O. Box 25486

Denver Federal Center

Denver, Colorado S022S

GION 7

onal Director

U.S. Fish and Wildlife Service

lOll E. Tudor Road

Anchor••• Alaska 99503
.~.

USH. ","'IUK.I"". · st.HVKOt:

DEPARTMENT OF THE INTERIOR

u.s. FISH AND WILDLIFE SERVICE

."" ... ,... .

As the Nation's principal conservation agency, the Department of the Interior has responsibility for most of our .nationally owned public lands and natural resources. This includes

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