bluuebunny/crossref_metadata_2025 huggingface dataset:
AGE, EGG‐SIZE AND BREEDING SUCCESS IN THE HERRING GULL LARUS ARGENTATUS
Authors: Davis J. W. F.
Published: April 2008

The breeding biology of the Herring Gull Larus argentatus was studied in 1969, 1970 and 1972 on Skokholm, Pembrokeshire.

The distribution of laying dates in three years is given; median laying date was always about 10 May. Laying dates of individual pairs were fairly constant between two years, but females up to nine years of age apparently advanced their laying date in successive years. In 1969 there was a decline in clutch‐volume index during the season but this was not found in 1970 or 1972. Females laid clutches of similar volume in successive years, although the volume did vary with age, increasing up to 7 or 8 years of age and then declining. Hatching success was highest in the earliest of four periods in 1970 (69%) and lowest in the last (51%); in 1972 the corresponding figures were 71% and 63% and the seasonal trend was not significant. Chick mortality was higher in 1970 (69%) than in 1972 (59%); in 1970 there was significant seasonal variation in chick survival but in 1972 there was not. In 1970 chick survival was positively correlated with hatching weight (and hence egg‐size) and chick survival was also related to growth which was itself correlated with hatching weight. There were no such correlations in 1972. Mean chick production in 1970 was 0.60 per pair and in 1972 0.70. In both years later breeders were less successful, but the seasonal range of mean success was less in 1972.

In the discussion it is shown that some of these differences between years could be due to changes in the age structure of the population and it is suggested that the correlation between egg‐size and chick survival in 1970 may be an artefact of the age structure.
CRANE GRUS GRUS MIGRATION OVER SEA AND LAND
Authors: Alerstam Thomas
Published: April 2008

The detailed process of Crane Grus grus migration over sea and land, respectively, was studied from films of a radar station in Skåne, southernmost Sweden, during the spring migratory periods in 1972 and 1973.

The true air speed for travelling over the sea was 67 km h‐1, whereas over land the Cranes made use of thermal air to soar and gain height and the true air speed was 44 km h‐1. Soaring lasted on the average 6.3 min and the distance travelled between the soaring interludes was 13.3 km. True air speed during the flights between thermals was about 70 km h‐1.

The Cranes compensated completely for wind drift over land, but only incomplete compensation took place over the sea. The angle between the Cranes' heading and track directions over the sea was composed of 68% compensation and 32% drift.
THE INTERTARSAL JOINT OF THE HARRIER‐HAWKS POLYBOROIDES SPP. AND THE CRANE HAWK GERANOSPIZA CAERULESCENS
Authors: BURTON P. J. K.
Published: April 2008

The Harrier‐Hawks Polyboroides spp. and Crane Hawk Geranospiza caerulescens have legs capable of flexing backward as well as forward at the intertarsal joint. This is evidently adaptive to their habit of extracting prey from crevices using the feet. The structure and properties of the intertarsal joint have been investigated using an alcoholic specimen of P. typus and skeletons of P. typus and G. caerulescens; specimens of Circus cayaneus (alcoholic) and C. aeruginosus (skeleton) were used for comparison. Increased mobility of the joint extends to medial‐lateral swing as well as flexion; the faculty for backward flexion appears to be somewhat offset by some loss of forward flexion. The tibiotarsus, tarsometatarsus and the ligaments and menisci of the intertarsal joint are described and figured. No significant differences in musculature were found. The most obvious difference between Circus on the one hand, and Polyboroides and Geranospiza on the other is the extreme narrowness of the joint in the latter two genera. This is probably the most important factor permitting increased joint mobility. The possible significance of other structural features observed is also discussed, and related adaptations of the distal tarsometatarsus and foot are pointed out. It is concluded that the resemblances of the hind limbs of these two genera are not strong evidence of phylogenetic relationship.
SEASONALITY, DENSITY AND DIVERSITY OF BIRDS OF A PAPYRUS SWAMP IN WESTERN KENYA
Authors: BRITTON PETER L.
Published: April 2008

The commoner birds of a western Kenya papyrus swamp are listed. This avifauna is probably as rich as in any papyrus habitat, dominated by warblers (Sylviinae) in which interspecific competition between species of similar size is reduced by preference for swamp‐edge rather than interior habitats, preference for papyrus over standing water, or vertical habitat partitioning. Comparisons with other west Kenyan habitats show that it is a specialized avifauna with low species diversity indices and few species. Density figures for common species are higher than in forest undergrowth or thicket. There is little ecological diversity of habitat in uniform stands of papyrus which form ecological islands, and this high density may be interpreted as a density compensation on a speciespoor ‘island’ compared to a species‐rich ‘mainland’.

Rainfall is the most seasonally variable climatic factor in west Kenyan papyrus habitats. In this climatic area of Uganda and western Kenya there is a modal egg‐laying period from March to June coinciding with the long rains, and a postnuptial primary moult period from June to November, which extends into the short rains of October and November. On average, a complete moult of the remiges takes six or seven months. In general the moult of immatures begins and ends about two months later than adult moult, but birds reared during the short rains had primary moult only half complete at the beginning of the following long rains. There is very little evidence of interrupted moult. The 1969 rainfall pattern was exceptional, with the heaviest rainfall in February, and there is evidence of a correspondingly early onset of postnuptial moult in that year. Females moulted significantly earlier than males in 1969 whereas males moulted marginally earlier in other years, suggesting that female moult schedules are more flexible.
FACTORS AFFECTING BREEDING OF RAZORBILLS ALCA TORDA ON SKOKHOLM
Authors: LLOYD CLARE S.
Published: April 2008

A study of the breeding biology of the Razorbill was carried out on Skokholm (South Wales) during 1971‐73. Birds ringed or colour ringed before the study began provided additional information upon the effects of age on breeding. Mean laying date was delayed in 1972, compared with 1971; the effect is attributed chiefly to stormy weather which upset colony attendance. Eggs were also smaller in 1972. A seasonal decline in egg size (volume) was noted in all three years, attributed mainly to the later laying of young birds. Egg size increased with age, at least up to the fifteenth year. Eggs lost totalled 30% of those laid; 73% of this total was due to predation by Herring Gulls and of Jackdaws. Most losses (45%) occurred during the first 10 days after laying. Of lost eggs, 25% were replaced, usually 14 days after the loss of the original; only eggs laid and lost early in the season could be replaced.

Only 7% of the chicks which hatched failed to fledge. Most (62.5%) chick losses occurred in the first week of nestling life, when chick weight was related to egg size. Afterwards, both growth rate and fledging weight were independent of egg size. The chicks fledging early in the season were heavier than later chicks. Failure to fledge was mainly due to a breakdown in behaviour between parent and young, rather than to predation. Breeding success was highest for birds breeding early in the season, most of which were older, more experienced breeders. These laid early enough to replace an egg if it was lost; they produced large eggs, and their chicks were therefore both heavier than average during the critical first 7–10 days of life, and fledged at a high weight. Thus experience accumulated with age, and the ability to lay early in the season are important for successful breeding in the Razorbill.
THE INUNDATION ZONE OF THE NIGER AS AN ENVIRONMENT FOR PALAEARCTIC MIGRANTS
Authors: CURRY PETER J. , SAYER JEFFERY A.
Published: April 2008

Of at least 350 species so far recorded within the boundaries of the Niger Inundation Zone, no less than 108 (31%) are wholly or partially of Palaearctic origin. Five main habitats are recognized in the region: wetland, hygrophilous grassland, transition zone, non‐flooded areas and aerial. The habitats, the Palaearctic migrants and their possible Ethiopian competitors are described and discussed.

The annual Niger flood regime enables Palaearctic waterbirds to find suitable habitats somewhere within the region during all seasons, but most widely during the autumn and winter months of the flood recession. Non‐aquatic species inhabiting flood plain grassland are scarce during the Palaearctic autumn, when the growth of vegetation reaches its maximum, becoming commoner and more diverse during the winter months. Wetland warblers of the genera Acrocephalus and Locustella have not been recorded on autumn passage. It is suggested that in some years at least, these and other trans‐Saharan migrants from the West Palaearctic overfly the Sahelian latitudes of mid‐West Africa. Species inhabiting the transition zone (which increases in area during years of below average rains and floods) are most in evidence at the end of the winter period and during the spring hot dry season, prior to northward trans‐Saharan migration. Habitats and species encountered in the non‐flooded areas are similar to those recorded in the Sahel zone elsewhere in West Africa.

Aerial habitat is utilized by Common Swifts arriving en masse in early August, at the maximum development of the south‐westerly monsoon airstream. Several aquatic species and the first few trans‐Saharan migrants also occur during the summer rainy season.

Some species (e. g. Whiskered Tern, Lesser Kestrel, Turtle Dove, Short‐toed Lark and Sand Martin) are most numerous during the late winter and spring hot seasons, when conditions provided by the Inundation Zone may be more suitable for pre‐migration feeding than in other parts of the Sahel zone. As yet there is virtually no information available to determine any effects that drought seasons or flood variation may have on the migrant populations.
THE PLUGGED PORES OF TINAMOU (TINAMIDAE) AND JAÇANA (JACANIDAE) EGGSHELLS
Authors: PERROTT R. G. BOARD & H. R.
Published: April 2008

By means of scanning electron microscopy and X‐ray probe analysis the eggshells of several species of tinamou and jaçana have been investigated. A plugged pore system has been shown which were hitherto unrevealed by other methods. The plug in the pore of the tinamou was rich in sulphur and that of the jaçana eggshell contained upwards of 5% iron.
AUTUMN MIGRATION OF QUAIL COTURNIX COTURNIX AT THE NORTH COAST OF THE SINAI PENINSULA
Authors: Zuckerbrot Yechiel D. , Safriel Uriel N. , Paz Uzi
Published: April 2008

Autumn migration of Quail was studied on the northern coast of Sinai in 1972 and 1973. Arab Quail nets were used to catch totals of 4863 and 1823 in the two years, respectively. Of 1761 Quail ringed in 1973, 0–4% have been recovered from the extensive area predicted by earlier ringing results.

Quail started to enter nets 10 min after first light, and continued to do so until 0800–0900 h, local time. The quantity netted per day varied greatly, producing waves of migration which were inversely correlated with the barometric pressure over Europe prior to the arrival of each wave. Each of the arriving waves was apparently a discrete (group of) populations) from one area. The very close similarities in the arrival dates of each wave for both the 1972 and 1973 passages has been interpreted as showing that the timing of autumn migration in Quail is mainly dependent on exteroreceptive time–setters and/or biological clocks.

Sex and age ratios of each day's catch varied greatly and were related to the rise and fall in numbers of Quail arriving each day. The approximate sex and age ratios for all Quail crossing the coast after dawn during the 1973 passage was 58% male, 75% young, and 7–2 young per adult female.

The 26 Quail analysed for fat and water content were definitely not suffering from dehydration, but many of them would not have been able to reach their wintering grounds without additional food. The ‘average’ Quail had 75% of the fat reserves required, while less than 20% of the Quail had the required amount.

The daily temporal pattern of netting suggests that a proportion of the Quail cross the coast before dawn and alight at dawn well dispersed within the Sinai desert. This, together with the observed inverse correlation between the amount of fat at arrival and the time of netting, suggest that it is the Quail in poorer physiological condition that arrive later in the day, and that these may stand smaller chances of completing their autumn migration even if not netted by man.

More than three times the number of Quail were caught per metre net in 1972 than 1973 (2–43 Quail/metre net/season and 0–73 Quail/metre net/season, respectively. This decline cannot be attributed to hunting. Rough quantitative data during the years 1900–1959 shows that the abundance of Quail in any year was not dependent on abundance in the preceding year. On the other hand, fluctuations in Quail abundance were associated with long–term climatic changes, i.e., netting success in Egypt was negatively associated with rainfall in the Sahel, and shooting in Luxembourg was positively correlated with temperatures in Germany.
BIOLOGICAL NOTES ON THE GIANT COOT FULZCA GIGANTEA
Authors: Fjeldsa Jon
Published: April 2008

The Giant Coot is generally a local and sparse bird in Andean lakes at 3100–5000 m. One of the localities found by the author, Lake Lagunillas in southern Peru, contained 600–650 nesting pairs increasing the known population markedly. The enormous offshore nests are completely open to view. They begin as floating structures but as they increase in size, rest on the bottom like islands. Since the central parts of large nests turn into compact peat, they are probably used for years in succession. Thriving breeding populations may require extensive shallows with dense weeds such as Myriophyllum and Potamogeton at the water surface. New materials are added to the high nest‐rim as long as pairs have young and this serves as a continuing food supply for the chick, permitting them to stay dry and sheltered during bad weather.

The threat behaviour differs markedly from that of other coots studied. The main breeding season is in the austral winter when there is intense cold every night, with second broods in spring and some laying at other seasons. Development appears very slow. Territorial adults seem sedentary and flightless. It is assumed that the species disperse through nocturnal flights, probably by immatures which have not yet obtained full weight.
THE CHARACTERISTICS AND OCCURRENCE OF COOPERATIVE POLYANDRY
Authors: Faaborg John , Patterson Cindy B.
Published: April 2008

This paper discusses the relative position of cooperative polyandry among models for the evolution of both polyandry and cooperative breeding. Cooperative polyandry is described as the situation where more than one male and one female breed as a group with males sharing equally in copulations and the care of one set of young. Sequential and simultaneous polyandry are defined to show how they differ from cooperative polyandry. These systems generally are characterized by the care of only one parent for each set of young, a trait which is in sharp contrast to cooperative polyandry. An argument is made that the present models for the evolution of polyandry cannot be expanded to include the cooperatively polyandrous species. Instead, the cooperative traits of cooperative polyandry fit within the array of characteristics of cooperative (communal) breeding. General characteristics of all cooperative species (monogamous, promiscuous and polyandrous) are reviewed and possible reasons for the evolution of equal‐status males are discussed. A plea is made for the unification of evolutionary models dealing with mating systems and cooperative systems.
ABUNDANCE AND SEASONALITY OF THE SAVANNA AVIFAUNA AT PORT MORESBY, PAPUA NEW GUINEA
Authors: BELL H. L.
Published: April 2008

The results of 156 transect counts carried out over 30 months in savanna of the Coastal Hill Zone, Port Moresby, Papua New Guinea, are analysed. The avifauna is depauperate compared to similar habitats in New Guinea and temperate Australia. Twelve common species of the Port Moresby savannas were not so in the Coastal Hill Zone and reasons for their rarity are given. Most species present are solely savanna forms but some are dependent upon the presence of small patches of monsoon forest. Average density of birds was estimated at 55 per 10ha, a very low figure compared to New Guinean rainforests. Carnivores and mixed‐feeders make up two thirds of numbers present but frugivores, because of their large individual size, are a significant proportion of biomass. There was little significant seasonal difference in overall numbers except for granivores which decline in numbers during the wet season. However, individual species show regular seasonal fluctuations reasons for which are postulated. A correlation exists between flowering of trees and numbers of certain species, and also between the annual grass‐fires and numbers of certain grassland species. Merops ornatus, Lalage sueurii and Coracina novaehollandiae, considered in the literature to be wintering migrants, are also shown to be breeding residents. Breeding records for 462 species were analysed. Most breeding of insectivores and mixed‐feeders occurs in the Austral spring during the dry season and ends before the onset of heavy rains. Granivores breed in the late wet season. The few records for frugivores indicate a wet season peak.
EGG COMPOSITION AND HATCHLING PRECOCITY IN SEABIRDS*
Authors: WILLIAMS A. J. , SIEGFREID W. R. , COOPER J.
Published: April 2008

This paper presents analyses of the composition (shell, yolk, albumen) and of the quality (lipid, protein and water contents) of yolk and albumen of eggs of 25 species of seabirds belonging to the Sphenisciformes, Procellariiformes, Pelecaniformes, and Lari of the Charadriiformes. These data are compared with those published for species in the same orders and suborders, and the combined seabird data are compared with published data for non‐seabirds.

Variation in the proportionate weight of eggshell is not related to hatchling precocity but is probably due to adaptive differences in nest substratum and the agility of the incubating birds. Lipid and protein contents of yolk, and water content of albumen, are uniform in eggs of all examined species. Protein levels of albumen and water content of yolk and of entire egg contents vary greatly between taxa.

Contrary to previous claims there is no simple relationship between egg composition and hatchling precocity. Differences in egg composition will probably only be clearly understood when the nutritional needs of the embryo, and of the hatchling in the time before it regularly obtains food, are known.
Habitat selection, foraging niches and horizontal spacing of Willow Warbler Phylloscopus trochilus and Chiffchaff P. collybita in an area of sympatry
Authors: Sæther Bernt‐Erik
Published: April 2008

Habitat selection of the Willow Warbler and the Chiffchaff was studied along a succession of grey alder forest in Central Norway (63oN) where both species breed. Both were found in all serai stages, but there was a slight tendency for the Willow Warbler to be found more often in the voungest stages than was the Chiffchaff.

Foraging niches and horizontal spacing were studied within one particular forest. Most of the records of both Willow Warbler and Chiffchaff came from the tree layer, and the overlap between the species in their foraging niches was considerable. However, the species were found to occupy almost mutually exclusive territories.
The sensitivity of echolocation by the Grey Swiftlet Aerodramus spodiopygius
Authors: Smyth D. M. , Roberts J. R.
Published: April 2008

Experiments were carried out to study the sensitivity of the echolocation system of the Grey Swiftlet Aerodramus spodiopygius to cylindrical aluminium rods of 1, 5, 10 and 20 mm diameters. Using a method of statistical analysis which enabled the data to be compared with the chance performance of a randomly moving (non‐echolocating) missile, the results indicated that this species could echolocate the 20 mm diameter rods but those of smaller diameter were hit in an approximately random fashion. It is concluded that the sensitivity threshold of A. spodiopygius lies between 10 and 20 mm diameter for cylindrical metal rods under the prevailing experimental conditions. Comparisons with other data on the sensitivity of this and other swiftlet species are discussed.
The influence of prey fluctuations on the breeding success of the Tawny Owl Strix aluco
Authors: Wendland V.
Published: April 2008

A population of 17 to 20 pairs of Tawny Owls was studied from 1959–79 in Grunewald forest, West Berlin. The breeding success of the Owls (21–77% of pairs raising young per year) and the proportion of yellow‐necked field mice Apodenzus flavicollis in their pellets (13–48% of prey items each year) exhibited the same three‐year cycle. Long‐term trends in the diet of the Owls were apparent and reasons for these are discussed.
Spread‐winged behaviour of Double‐crested and Flightless Cormorants Phalacrocorax auritus and P. harrisi: wing drying or thermoregulation?
Authors: III Willard W. Henyemann.
Published: April 2008

The behaviour of free‐living Double‐crested and Flightless Cormorants, and the thermoregulation of Flightless Cormorants, were studied in the field to determine the influence of weather and the function of wing‐spreading. The behaviour of both species was sensitive to changes in ambient temperature and insolation intensity. Spread‐winged behaviour in both species w‐as displayed only by wet individuals and was never accompanied by gular flutter. The frequency of spread‐winged behaviour in Double‐crested Cormorants was not correlated with ambient (shade) temperature or solar intensity. In Flightless Cormorants, however, the frequency of wing‐spreading was positively correlated with ambient temperature, and negatively correlated with insolation intensity. Body temperatures in Flightless Cormorants were statistically higher during the day than during the night, while gular fluttering than while not gular fluttering, and before entering the water than after leaving the water. There were no significant differences in the body temperatures of Flightless Cormorants after wing‐spreading as compared to before ‘sunning’. Spread‐winged behaviour in these cormorants appears to function primarily in wing drying and not in gaining or losing heat, although the ultimate goal of wing drying may be to conserve metabolic energy.
Variation in egg quality and composition in the Mallard Anas platyrhynchos
Authors: BIRKHEAD MIKE
Published: April 2008

Three complete Mallard Anas platyrhyncos clutches from a single site were analysed to determine intra‐and inter‐clutch variation within and among clutches in quality and composition. Variation between clutches was significantly greater than within clutches in all the examined criteria of egg composition, except for the percentage of water found in yolk. In addition the weight of the yolk was proportional to fresh egg weight. When log transformations were used, the slope of the regression was greater than unity, indicating the proportional contribution of yolk increased respectively with egg weight. A total of 26 eggs from four locations was analysed and no regional variation in egg composition was found but there was variation in egg quality (lipid and protein). The factors affecting the production of a ‘good egg’ and what in fact is a ‘good egg’ are discussed. In the Mallard, as in other Anseriformes, it appears that larger eggs may confer a survival advantage to the subsequent young.
A revision of the babbler genus Trichastoma and its allies (Aves: Timaliinae)
Authors: RIPLEY S. DILLON , BEEHLER BRUCE M.
Published: April 2008

By means of a comparative analysis of 12 morphological and behavioural characters, the timaliine genus Trichastoma and its relatives in the tribe Pellorneini are revised to reflect new understanding of inter‐ and intrageneric relationships (cf. Mann et al. 1978). Trichastoma as constituted by Deignan (1964) is here subdivided into three unambiguously monophyletic genera, the Malayan Trichastoma and Malacocincla, and the African Illadopsis.

Evidence is presented indicating that the reconstituted Trichastoma should be considered the stem genus for the tribe. Reviewing the distribution of morphological and behavioural characters, the general implication is that the African forms share a recent common ancestor with those from Asia. Distributional data support the contention that the group originated in the Malayan region and colonized westward through southern Asia and Arabia to Africa (probably in early Quaternary) when humid and warm conditions fostered a continuous Afro‐Asian corridor of tropical wooded habitats. The postulated greater age of the pellorneine assemblage in Malaysia, along with the region's insular geography, has fostered a larger species radiation than that in continental Africa. Recent desiccation of Arabia and central and northwestern India probably caused widespread regional extinction of linking forms and has isolated the Pellorneini into two humid forest refuges in equatorial Africa and eastern Asia.
The breeding success of the Indian Cattle Egret Ardeola ibis in eastern Australia
Authors: MCKILLIGAN N. G.
Published: April 2008

Over a three year study the Cattle Egret's mean clutch size was 3.6 eggs and 81% of nests with eggs produced one or more fledglings. Breeding success averaged 2.1 chicks to fledgling stage, and between 1.5 and 1 8 fledged per nesting pair. These data illustrate the breeding performance of a population in an expansion phase of its history. The determinants of growth of immigrant Cattle Egret populations are sought in a comparison of its breeding parameters in different lands. A significant reduction in clutch size occurred after about two‐thirds of clutches had been laid each year. One‐year‐old birds nesting for the first time are implicated in this reduction.
Factors affecting duckling survival of Eiders Somateria mollissima in northeast Scotland
Authors: MENDENHALL VIVIAN M. , MILNE H.
Published: April 2008

Mortality factors affecting Eider ducklings Somateria mollissima and their impact with respect to age were studied on the Ythan estuary, Aberdeenshire, Scotland. Survival from hatching to fledging averaged 10.4% over 13 years; numbers declined steeply during the first three to four weeks and slowly thereafter. Growth of tagged young varied considerably between broods. Mortality was not correlated with numbers of ducklings or adults.

Predation in 1974 averaged 13.6% per day during the first two weeks, and accounted for most mortality. Herring Gulls Larus argentatus were the principal predators. Predation was 2.5 times as high in rainy, windy weather as in fine, calm weather. Weather, primarily mean rainfall and wind speed, during early life accounted for over 90% of all variation in survival during eight of nine years. Predation was considered the proximate factor in most weather‐related mortality. High survival in 1971 was not explained by weather. An estimated 25–40% of mortality during the second week of life was from renal coccidiosis Eimeria somateriae. Reproductive output of the Ythan population probably limits the rate of population growth, but numbers of breeding birds seem to be regulated by other factors acting after fledging.
Breeding success and the question of clutch size of Northwestern CrowsCorvus caurinus
Authors: RICHARDSON HOWARD , VERBEEK NICOLAAS A. M. , BUTLER ROBERT W.
Published: April 2008

The breeding biology of two island populations of the Northwestern Crow was studied in British Columbia over a period of five years. Both populations laid an average of four eggs per clutch, of which approximately 75% hatched. More young survived to fledge on Mandate than on Mitlenatch Island. The young from nests close (< 100 m) to the beach on Mitlenatch had a higher survival rate than those from further inland. The number of eggs lost or failing to hatch was lowest in clutches of four eggs. There was a non‐significant trend for chick survival to be inversely related to clutch size. The net result was that clutches of five eggs produced no more young than did clutches of four eggs. It is suggested that the major limiting factor on clutch size is food availability but the decreased hatching success of any remaining eggs once hatching has started is also a contributing factor.
Spacing of Golden Eagle Aquila chrysaetos nests in relation to nest site and food availability
Authors: TJERNBERG MARTIN
Published: April 2008

A regular nest spacing of Golden Eagle pairs was found in every carefully searched area within the species range in Sweden. The spacing regularity of nests used by pairs in forests (mostly tree‐nesting) was similar to that in mountain areas (cliff‐nesting), indicating that regular nest spacing is affected more by spacing behaviour than by shortage of nest sites. Distances to nearest neighbours were shorter in the mountain region (mean distance 102 km) than in the forests (170) of northern Sweden. Densities of the most important prey species for Golden Eagle were apparently higher in the mountains than in the forests. Differences in topography and habitat diversity between the two regions may also have contributed to the difference in breeding density.
Factors influencing the abundance of breeding Dippers Cinclus cinclus in the catchment of the River Wye, mid‐Wales
Authors: ORMEROD S. J. , BOILSTONE M. A. , TYLER STEPHANIE J.
Published: April 2008

The number of breeding Dippers was assessed in relation to environmental features and benthic macro‐invertebrates over 220 km of tributaries in or adjacent to the catchment of the Welsh River Wye in 1982. Bivariate regression and multivariate analysis revealed strong correlations between breeding abundance and combinations of variables describing stream‐gradient and the relative abundances of larval Trichoptera and nymphal Plecoptera. The results are discussed in relation to aspects of the feeding ecology of breeding Dippers and their nestlings.
Foraging success of adult and juvenile Starlings Sturnus vulgaris: a tentative explanation for the preference of juveniles for cherries
Authors: STEVENS JAN
Published: April 2008

Analysis of foraging success of adult and juvenile Starlings in June, July and August indicates that juveniles are less successful than adults at catching their animal food, especially leatherjackets. I suggest that this low success in gathering animal food effectively causes a shortage that drives young Starlings to eat easily accessible cherries.
Water loss from Jackass Penguin Spheniscus demersus eggs during natural incubation
Authors: YOM‐TOV Y. , WILSON R. , AR AMOS
Published: April 2008

The water budget of incubating Jackass Penguin eggs was studied on Marcus Island, South Africa, and complementary measurements were made in the laboratory. The mean ambient temperature was 16‐5 “C and the mean humidity was 12‐4 Torr (89% relative humidity). The temperature of incubated live and water‐filled eggs ranged between 14oCand 37 oC. The mean calculated egg temperature was 34‐9‘ C. The mean brood patch temperature was 37‐1 oC, slightly lower than the cloacal temperature (37.8 oC). The mean brood patch area was about 38 cm2. The rate of water loss was 411 mg day‐1. The total diffusive water loss during 37 days of incubation was, as predicted, 15‐2% of the initial 100‐3 g egg mass. The total pore number was 6245 per egg and the shell thickness was 577 fira. It is suggested that the eggshell parameters, incubation length and nesting behaviour are compensated in such a way that an egg‐to‐nest water vapour pressure difference lower than commonly found is sufficient to bring about the normal total water loss.
Diet, food availability and habitat selection of breeding Common Sandpipers Actitis hypoleucos
Authors: YALDEN D. W.
Published: April 2008

The diet of the Common Sandpiper, as studied by faecal analysis, includes a wide variety of prey, the majority of which are of terrestrial rather than of aquatic origin. Observation of feeding activity confirms that much time is spent feeding in grassland, although shingly river edges are also important. The feeding activity of young chicks is also largely confined to wet grassy areas, but older chicks feed almost entirely along the
Rain, breeding success and distribution of Capercaillie Tetrao urogallus and Black Grouse Tetrao tetrix in Scotland
Authors: MOSS R.
Published: April 2008

The number of chicks reared by Capercaillie was inversely related to the number of days with rain during and just after their hatching. However, rain had no detectable effect on the breeding success of Black Grouse on the same study area. The breeding distribution of Capercaillie in Scotland is more limited than that of Black Grouse, which extends into rainier areas. It is speculated that sexual selection for large size in Capercaillie has indirectly caused their chicks to be more vulnerable to rain and, consequently, has limited their distribution to less rainy areas.
Divergent character displacement in the song of two allospecies: the Pied Flycatcher Ficedula hypoleuca, and the Collared Flycatcher Ficedula albicollis
Authors: WALLIN LARS
Published: April 2008

Songs of the three flycatcher forms, Ficedula hypoleuca hypoleuca, Ficedula albicollis albicollis and Ficedula albicollis semitorquata, were distinguishable from one another using a multivariate analysis. F. albicollis semitorquata, which has an intermediate song character, is considered to be a primary allopatric form while the nominate subspecies of albicollis is assumed to be dispersed into sympatry with F. h. hypoleuca. The differences in song between the nominate albicollis and F. hypoleuca are accentuated in their zone of sympatry and are mostly due to divergence in the albicollis song. The song is primarily an epigamic vocalization in the two species and conforms to the pattern characteristic of divergent character displacement associated with reproductive behaviour. Two alarm calls are quite similar in the two species and are the main vocalizations associated with territorial combat. Their interspecific territorial behaviour has apparently not been affected in areas of sympatry.
Interrelation between moulting and breeding in a tropical population of the House Sparrow Passer domesticus
Authors: MATHEW K. L. , NAIK R. M.
Published: April 2008

Under the tropical regime in Rajkot, India, the House Sparrow Passer domesticus had a prolonged breeding season, so that breeding and moulting of the primaries overlapped. The moult was interrupted commonly in the nesting birds and was observed more frequently in females than in males. It is concluded that moult initiation was not controlled by reproductive hormones in any way. It is also suggested that the reproductive hormones may not be directly involved with moult interruption.
Ecology of migrant Black‐necked Grebes Podiceps nigricollis at Mono Lake, California
Authors: WINKLER DAVID W. , COOPER SCOTT D.
Published: April 2008

Autumnal migrant Black‐necked or Eared Grebes Podiceps nigricollis begin arriving in large numbers at Mono Lake, California, in August. Juveniles appear to arrive later than adults, and the number of grebes at Mono Lake peaks in September and October. The grebes leave by November or December. Stomachs of 73 grebes collected in the Autumns of 1980 and 1981 reveal that brine shrimp Artemia monica comprise over 90% of the diet. The remainder of the diet is composed of the larvae, pupariaand adults of a brine fly Ephydra hians and small numbers of shore bugs Saldula arenicola and 5. opiparia and other terrestrial arthropods. The grebes do not feed at night but rest instead in large nocturnal aggregations over deep water. Grebe fat stores and total body‐weight increase from August to October, and adults moult their regimes in August and September. In late autumn brine shrimp densities decline dramatically and the grebes leave the lake.
The pair bond and divorce among Oystercatchers Haematopus ostralegus on Skokholm Island, Wales
Authors: HARRIS M. P. , SAFRIEL U. N. , BROOKE M. DE L. , BRITTON C. K.
Published: April 2008

Mate changes of Oystercatchers were followed over a 15‐year period. In 8.0% of instances, the pair split up between breeding seasons even when both members bred the second season. The likelihood of divorce was highest for birds aged five years, the modal age of first breeding. After divorce birds did not select an older or younger mate when re‐pairing. Low hatching success increased the chances of divorce. Divorce was not followed by significant changes in clutch‐size, laying date or nesting success (although females tended to be more successful).
Observations on the mass migration of Bridled Terns Sterna anaethetus off the coast of Colombo
Authors: SILVA REX I. DE
Published: April 2008

A mass migration of Bridled Terns Sterna anaethetus has been observed periodically off the south western coast of Sri Lanka during the past several years (Hoffmann 1975, Phillips 1978) and it is now evident that the phenomenon is an annual occurrence A preliminary study was initiated in 1981 (De silva 1982) and the results encouraged the continuation of observations until late October 1984 Only those aspects of migration which were visible from land are dealt with here
An experimental manipulation of clutch and brood size of White‐rumped Swiftlets Aerodramus spodiopygius of Fiji
Authors: TARBURTON M. K.
Published: April 2008

By monitoring hatching success, chick growth and fledging success in normal sized and experimentally enlarged clutches and broods of the White rumped Swiftlet Aerodramus spodiophygius in Fiji this paper demonstrates the inability of this species to raise more young than is normal.
A spectrographic analysis of the loud calls of Helmeted Hornbills Rhinoplax vigil
Authors: HAIMOFF ELLIOTT H.
Published: April 2008

Helmeted Hornbills Rhinoplax vigil inhabit the tropical and montane forests of Borneo, Sumatra, Malaysia, and Peninsular Thailand. Although little is known of their social behaviour and ecology, it is believed that they are monogamous and strictly territorial. The males have been observed to produce loud calls audible up to 2–3 km at various times throughout the day, but no studies of these calls have been made previously. An audiospectrographic analysis of the loud calls produced by several wild Helmeted Hornbills was conducted. The sounds comprising the loud calls were relatively pure in tone with few harmonics, with most of the energy produced between 500–1500 Hz, suggesting that selection may have favoured the long‐range transmission of these sounds through the forest. These calls are organized into two distinguishable parts, and it is suggested that the first part may primarily serve as a means of attracting the attention of neighbouring non‐mate conspecifics, while the second part may serve as an advertisement of age, size, or physical condition.
Validation of the stomach‐flushing technique for obtaining stomach contents of Penguins
Authors: GALES R.P.
Published: April 2008

The efficiency of the stomach flushing technique in obtaining complete stomach contents was tested on Little, Gentoo and Rockhopper Penguins. This technique was validated by feeding the penguins known amounts of fish and subsequently flushing their stomachs after specified time intervals. Examination of the contents showed that the method is effective and offers an alternative to killing penguins in order to obtain stomach contents. The effects of different states of stomach fullness on food recovery rates highlighted the necessity for multiple flushing. Quantitative information on the effect of time between feeding and stomach flushing on the recovery rates was also obtained. Where stomach contents were relatively undigested the rate of retrieval of fish was 90–100%, but this rate decreased with time and in no cases in which stomach contents were in advanced stage of digestion was the retrieval rate higher than 80o. Inclusion of the Gentoo and Rockhopper Penguins in the validation trials showed that the size of the penguin does not affect recovery rate.
Social structuring at a communal roost of Choughs Pyrrhocorax pyrrhocorax
Authors: STILL E. , MONAGHAN P. , BIGNAL E.
Published: April 2008

The social structure of a communal roost of Choughs Pyrrhocorax pyrrhocorax was studied between July and September 1985. Different age classes within the roost were spatially segregated. Third‐year birds were significantly more likely to attack another Chough and roosted in the densest part of the roosting flock. First‐year birds roosted significantly lower down the roost cliff and on the periphery of the flock.
Avian use of man‐disturbed forest habitats in the Eastern Ghats, India
Authors: BEEHLER BRUCE M. , RAJU K. S. R. KRISHNA , ALI SHAHID
Published: April 2008

Short‐term, fixed‐line surveys using mist‐nets and visual censuses were made of bird populations on five plots in the Eastern Ghats of Andhra Pradesh. Plots included two segments of moderately‐disturbed hill forest, a remnant patch of humid ravine forest surrounded by young coffee, a mature coffee plantation with remnant natural forest overstory, and a sub‐mature teak monoculture. Species‐number and diversity (H') were measured to be highest in the two hill forest plots. Equitability was highest in the Teak plot. Population numbers were highest in one of the forest plots and the Coffee plot. ‘Over‐dominance’ by tramp species was exhibited in the Coffee plot, in which the three most common bird species (two bulbuls and a white‐eye) comprised more than half of the individuals censused. All censuses were dominated by non‐forest and forest‐edge species; few raptors and species larger than 100 g were recorded in censuses. The patch of Ravine Forest was species‐poor and yet supported several unusual species (e.g., Abbott's Babbler Malacocincla abbotti. Blue Chat Erithacus brunneus and Little Spiderhunter Arachnothera longirostris) found on no other plot. We suggest that: (1) the few remaining undisturbed tracts of moist deciduous and semi‐evergreen forest should be declared natural reserves with complete protection from disturbance; (2) future forestry development in upland southeastern India should exclude teak monocultu re except on badly disturbed or clear‐felled areas. Preferred development would feature coffee/ pepper plantation under maximum natural overstory, interspersed with remnant forest tracts for faunal and watershed protection. Such a combination would appear to have the least effect on the original forest avifauna.
Mating system and nesting biology of the Red‐necked Phalarope Phalaropus lobatus: what constrains polyandry?
Authors: REYNOLDS JOHN D.
Published: April 2008

In this five‐year study of Red‐necked Phalaropes on the coast of Hudson Bay, Canada, only 8% (5/59) of females were polyandrous. Seventy‐five percent were monogamous, and 17% did not obtain mates. All males obtained mates readily. To understand the low incidence of polyandry in this sex‐role reversed, non‐territorial mating system, aspects of the pair bond, nesting biology, and size and plumage dimorphism were examined.

Pair bonds lasted an average of 11 days and ended as soon as the clutch was completed. Polyandrous females initiated their second nests only seven days later. Since in most years nest initiation for the population as a whole spanned three weeks, there was ample time for multiple clutches. Energetic constraints may have played a limited role in constraining polyandry, but many females that had previously laid clutches courted incubating males or harassed pairs.

The major factor limiting polyandry appeared to be availability of mates. Because phalaropes generally breed in habitats that are less defensible than those of other role‐reversed shorebirds, they are less able to monopolize males in populations with equal sex ratios. Sexual size dimorphism is correspondingly smaller than in territorial role‐reversed shorebirds, although plumage variation between and within sexes in this study was strong (and invariant with age). Thus, despite the phalaropes' role‐reversal, the evidence indicates that monogamy may predominate, with sexual selection driven by the ability of females to produce second clutches opportunistically when receptive males are available.
Selection against large size in the Sand Martin Riparia riparia during a dramatic population crash
Authors: JONES GARETH
Published: April 2008

In 1984 breeding Sand Martins declined to 27% of their 1983 numbers at a large colony in Scotland. A population crash of similar magnitude occurred over much of central Scotland and over Britain as a whole. The decline in numbers was probably attributable to severe drought conditions experienced overwinter in the Sahel zone of Africa. There was a significant reduction in the mean keel‐length of Sand Martins captured at the main study colony in 1984 compared with individuals measured in both 1982 and 1983, suggesting that selection for small body‐size had occurred during the period of high overwinter mortality.
The influence of pair‐status on the breeding behaviour of the Kittiwake Rissa tridactyla before egg‐laying
Authors: CHARDINE JOHN W.
Published: April 2008

The breeding behaviour of individually marked Kittiwakes Rissa tridactyla that retained mates from the previous year (SAME) was compared, over the period from pair‐formation to egg‐laying, with those that changed mates (CHANGE). Position of nest‐site in colony and breeding experience did not differ in the two groups studied. Hirds in CHANGE pairs attended the nest‐site more frequently and as a result probably had less ‘off‐duty’ time during which to forage. Rates of greeting were higher in CHANGE pairs. Differences between the two groups were usually greatest during the first two weeks after pair‐formation an decreased toward egg‐laying. CHANGE pairs copulated over a longer period before egg‐ laying, but stopped copulating sooner than SAME pairs. Copulation rates were higher in SAME pairs immediately before egg‐laying. The causation of the behavioural differences between the two groups is discussed in terms of mate familiarity. It is suggested that the recorded differences explain the lower reproductive success in CHANGE pairs reported by other workers.
Aggression in shorebirds in relation to flock density and composition
Authors: METCALFE N. B. , FURNESS R. W.
Published: April 2008

The aggressive interactions of Turnstones and Purple Sandpipers feeding in wintering mixed‐species wader flocks could be classified into those involving food and those involving space. All observed interspecific encounters were of short duration and were initiated and won by the larger species; the majority did not involve food and were resolved by low‐intensity displays. Intraspecific interactions (a greater proportion of which involved food) were also resolved quickly and were usually won by the initiator. Space‐related encounters between conspecifics were more likely to be resolved than food‐related encounters just by threat displays. Aggression rates increased with flock densities. However, the increase in aggression with density was dependent on the species composition of the flock: both Turnstones and Purple Sandpipers were more likely to be involved in fights (both over food and over space) with conspecifics than with other species, indicating that the aggression costs of flocking were less in mixed‐species flocks.