bluuebunny/crossref_metadata_2025 huggingface dataset:
Seasonal changes in egg‐mass within and among clutches of birds: general explanations and a field study of the Blackbird Turdus merula
Authors: MAGRATH ROBERT D.
Published: April 2008

In many populations of birds there is a seasonal change in the mean mass of eggs in the clutch. This might be caused by seasonal changes in the costs of egg‐production, or changes in the benefits of laying eggs of different size. In the Blackbird Turdus merula the mean mass of an egg correlated specifically with the air temperature during the period when it was predicted to be undergoing rapid follicular growth. There was no residual effect of date or day‐length on egg‐mass when statistically controlling for temperature during the period of rapid yolk synthesis, yet temperature still had a significant effect when controlling for date or day‐ length. Thus the seasonal increase in egg‐mass appears to be due to changes in the cost of egg‐production, not changes in the benefits of laying larger eggs. However, I could find no effect of food supply during laying on the mean mass of eggs in the clutch, either using an indirect measure of food availability, rainfall, or in a food‐supplementation experiment. This could be because females responded to extra food by laying earlier, and probably larger, clutches, rather than by increasing egg‐mass. The effect of temperature on egg‐mass increased through the laying sequence and there was a small seasonal increase in the mass of the last‐laid egg compared with the mean of the other eggs in the clutch. I propose that the mean mass of the last‐laid egg relative to the clutch mean, which can characterize a species or population, could evolve in response to the environmentally‐caused variance in the mass of the last‐laid egg: when the variance is high, the mean may have to be high to avoid producing unviable eggs.
The moult of Barred Warblers Sylvia nisoria in Kenya—evidence for a split wing‐moult pattern initiated during the birds' first winter*
Authors: LINDSTRÖM ÅKE , PEARSON DAVID J. , HASSELQUIST DENNIS , HEDENSTRÖM ANDERS , BENSCH STAFFAN , ÅKESSON SUSANNE
Published: April 2008

The moult of Barred Warblers Sylvia nisoria was studied during three winter seasons in southeastern Kenya at a southward passage site (Ngulia) and a wintering site (Mtito Andei). Most Barred Warblers migrating through Ngulia in November had yet to commence winter moult. These birds probably moulted subsequently in winter in northern Tanzania. In December, birds were found in heavy moult at Mtito Andei, and some of these birds were known to stay throughout the winter. By contrast, most birds reaching southeastern Kenya from late December onwards had already completed part or all of their winter moult, presumably at stopover sites in northern and eastern Kenya or in Ethiopia. Thus, winter moult in Barred Warblers takes place mainly in late November and December, either just before or soon after the final leg of autumn migration. In general, first‐year birds renewed all tertials and tail feathers, about three to five secondaries per wing and commonly also the outer one to four large primaries per wing. Adults renewed all tertials and tail feathers, almost all secondaries and only occasionally an outer primary. The replacement of relatively fresh juvenile secondaries during the birds' first winter implies that the split moult pattern of this species (secondaries, tertials and tail moulted in winter; primaries and tertials in summer) is endogenously controlled.
The altitude at which QuailCoturnix coturnixmigrate
Authors: Kane K. W. S.
Published: April 2008

There have been, over the years, conflicting statements by various authors regarding the altitude at which QuailCoturnix coturnixmigrate.
Variation in the abundance of Red‐breasted Mergansers Mergus serrator on a Scottish river in relation to season, year, river hydrography, salmon density and spring culling
Authors: MARQUISS MICK , DUNCAN KEITH
Published: April 2008

Red‐breasted Mergansers Mergus serrator were counted in the river North Esk, Scotland, and on the sea nearby, 1987–1990. Pairs arrived at the river estuary from early winter, but the main influx to freshwater took place in late April and in May, when breeding pairs dispersed far upriver. Females began incubation from late May. Most young hatched in July and fledged by late September. Males left the river in June and congregated at an offshore moulting site, their numbers peaking in August, and dispersed rapidly in September.

Breeding density and total duckling production decreased with increasing distance upstream, decreasing river width and increasing gradient and elevation. The total number of breeding pairs and their distribution on the river were similar from year to year, despite variable numbers killed, suggesting a stable breeding population near the upper limit the habitat would support in those years. It also suggested that killing mergansers in April was an ineffective way to reduce the population. The spatial variation in merganser breeding density was not correlated with the density of their main spring food, parr of salmon Salmo salar, but could have been related to its availability.

The production of well‐grown ducklings varied annually and was inversely correlated with river flow during the main period of hatch. It is argued that Red‐breasted Mergansers breed late in the year because the hatching of ducklings in July coincides with an abundance of their food, large aquatic invertebrates and tiny juvenile fish.
Do Levant Sparrowhawks Accipiter brevipes also migrate at night?
Authors: STARK HERBERT , LIECHTI FELIX
Published: April 2008

Flight paths of visually identified Levant Sparrowhawks Accipiter brevipes on autumn migration were analysed with a tracking radar in the Arava Valley, Israel. This time of the year there are no significant numbers of other species with a similar wing‐beat pattern. This wing‐beat pattern was found not only in daytime but also frequently at night. It is suggested that the Levant Sparrowhawk uses two strategies of migration: (1) soaring and gliding to reduce energy consumption; (2) flapping flight to reduce time spent on migration. The latter may be more important towards the end of the migratory season and/or when birds have become separated from the main migratory stream.
Vocal mimicry in wild African Grey Parrots Psittacus erithacus
Authors: CRUICKSHANK ALICK J. , GAUTIER JEAN‐PIERRE , CHAPPUIS CLAUDE
Published: April 2008

The ability of captive Grey Parrots Psittacus erithacus to imitate heterospecific sounds is well known. Analysis of a sound recording from Zaire reveals the first evidence of vocal mimicry in the wild of nine species of birds and a bat. Examination of recordings from Gabon and the Ivory Coast indicates that vocal mimicry may be widespread in wild populations. Possible reasons why this phenomenon has not been detected before are discussed.
Richard Meinertzhagen—a case of fraud examined
Authors: KNOX ALAN G.
Published: April 2008

Museum collections are rich repositories of information. The specimens and the data they bear continue to provide new insights into ornithology and biological processes decades or even centuries after they were collected. The benefits to be gained from museum collections depend implicitly upon the accuracy of the information associated with the specimens and the correct interpretation of those data (Parkes 1989, Knox & Walters 1992). Collectors and dealers have often been suspected of fabricating data for a variety of reasons, but proven cases have been documented only rarely (e.g. Nicholson & Ferguson‐Lees 1962). This paper examines one such case.
Clutch size of passerines at mid‐latitudes: the possible effect of competition with migrants
Authors: YOM‐TOV YORAM
Published: April 2008

The clutch sizes of the passerines of Israel and the Cape Province, South Africa, which lie at similar latitudinal range, were compared. Mean clutch sizes in Israel and the Cape Province are 4.09 and 2.87, respectively. Mean clutch size of Israeli migrants is larger than that of residents (4.45 and 3.93, respectively), but no such difference exists in the Cape Province.

It is suggested that the larger clutch size in Israel is a result of two factors: (1) the higher proportion of wintering birds in Israel in comparison with the Cape Province and the presence of many transients there which may compete with resident birds and cause high winter mortality among them and (2) a higher proportion of migrants in the Israel avifauna, which suffer heavy losses during their trans‐Saharan migration in comparison with Cape Province migrants, which travel shorter routes. The resulting reduced competition for food during the breeding season in Israel enables passerines there to lay larger clutches as predicted by Ashmole (1963) and Ricklefs (1980).
Diet composition of Emperor Penguin chicks Aptenodytes forsten‘ at two Mawson Coast colonies, Antarctica
Authors: ROBERTSON GRAHAM , WILLIAMS R. , GREEN KEN , ROBERTSON LYNNE
Published: April 2008

The diet composition of Emperor Penguin Aptenodytes forsteri chicks was examined at Auster and Taylor Glacier colonies, near Australia's Mawson station, Antarctica, between hatching in mid‐winter and fledging in mid‐summer by “water‐offloading” adults. Chicks at both colonies were fed a similar suite of prey species. Crustaceans occurred in 82% of stomach samples at Auster and 87% of stomachs at Taylor Glacier and were heavily digested: their contribution to food mass could not be quantified. Fish, primarily bentho‐pelagic species, accounted for 52% by number and 55% by mass of chick diet at Auster, and squid formed the remainder. At Taylor Glacier the corresponding values were 27% by number and 31% by mass of fish and 73% by number and 69% by mass of squid. Of the 33 species or taxa identified, the fish Trematomus eulepidotus and the squid Psychroteuthis glacialis and Allu‐roteuthis antarcticus accounted for 64% and 74% of the diets by mass at Auster and Taylor Glacier, respectively. The sizes of fish varied temporally but not in a linear manner from winter to summer. Adult penguins captured fish ranging in length from 60 mm (Pfeura‐gramma antarcticum) to 250 mm (T. eulepidotus) and squid (P. glacialis) from 19 to 280 mm in mantle length. The length‐frequency distribution of P. glacialis showed seasonal variation, with the size of squid increasing from winter to summer. The energy density of chick diet mix increased significantly prior to “fledging”.
Ranges of males of the Great Hornbill Buceros bicornis, Brown Hornbill Ptilolaemus tickelli and Wreathed Hornbill Rhyticeros undulatus in Khao Yai National Park, Thailand
Authors: POONSWAD PILAI , TSUJI ATSUO
Published: April 2008

Ranges of individual males of three hornbill species were determined by radio telemetry during the breeding and non‐breeding seasons in Khao Yai National Park, Thailand. Two Great Hornbills Buceros bicornis and two Brown Hornbills Ptilolaemus tickelli were studied in both 1988 and 1989, and two Wreathed Hornbills Rhyticeros undulatus were studied in 1989, 1990 and 1991.

In the breeding season, the home range of the Great Hornbill was 3.7 km2, similar to that of the Brown Hornbill (4.3 km2), while the Wreathed Hornbill occupied the largest home range (10.0 km2). In the non‐breeding season, the range size of the Wreathed Hornbill (28.0 km2) was greater than that of the Great Hornbill (14.7 km2). Differences in range sizes of different species may be related to differences in diet and breeding strategy. Ranges overlapped within and between the species, and this has implications for the estimation of the minimum area required for the conservation of hornbills within the Khao Yai National Park.
Mutual benefits of associations between breeding and non‐breeding White‐fronted Geese Anser albifrons
Authors: FOX A. D. , BOYD H. , BROMLEY R. G.
Published: April 2008

The relationships between yearlings and adult pairs of White‐fronted Geese Anser albifrons were studied during pre‐nesting, laying and early incubation in the central Canadian Arctic. Prior to nesting, females of lone pairs spent 75–81% of their time feeding, while males spent only 42–47% of time feeding and 46–50% alert. In pairs with one or more associated yearlings, both females and males fed significantly more and spent less time vigilant. Yearlings spent significantly less time (59%) feeding when alone compared with 71–76% when with pairs. Associations between yearlings and paired adults were most frequent before adult females began prospecting for nest sites. No prospecting pairs were associated with yearlings. After the egg‐laying period, groups of geese, predominantly yearlings, made distraction flights over humans and terrestrial predators approaching nests, in contrast to the more cryptic behaviour of nesting pairs. The presence of groups of geese associated with some nest sites suggests that continuing parent‐offspring relationships may involve assistance with nest defence.
Group composition and contributions to breeding by Rufous Vangas Schetba rufa in Madagascar
Authors: YAMAGISHP SATOSHI , URANO EIICHIRO , EGUCHP KAZUHIRO
Published: April 2008

The social system of the Rufous Vanga Schetba rufa was studied in a deciduous dry forest in Ampijoroa, western Madagascar. The species lived in groups of two to four individuals. Groups typically contained one adult female, one or two adult males and sometimes a (presumed) immature. All group members appeared to defend the territory. The presumed immatures had spotted throats and were smaller than adults in body size. They helped feed young and guard the nest but did not incubate or brood.
Growth of Stonechats Saxicola torquata from Africa and Europe: an analysis of genetic and environmental components
Authors: STARCK J. M. , KÖNIG S. , GWINNER E.
Published: April 2008

The postnatal growth of the European subspecies of the Stonechat Saxicola torquata rubicola and the African subspecies Saxicola torquata axillaris and their hybrids was studied to investigate differences in growth rates. Comparisons were made between subspecies, between genetically related chicks within subspecies and between individuals within sibling groups. Genetic and environmental effects on variation and their impact on the growth curves were evaluated. We compared posthatching increase in body mass and wing‐length between chicks raised under identical conditions and between chicks raised under different photoperiod and rearing conditions. Significant differences in body mass increase between the two subspecies were found for all parameters except for the inflection point of the growth curve. Differences in wing‐length occurred during the late posthatching development and were significant only for asymptotic size. However, interactions between independent variables masked the effects on some parameters. Furthermore, our data showed that the components of the total genetic variability are differently attributed to each level of comparison: we found the form of the growth curve and asymptotic size significantly different between subspecies; size at a given day and asymptotic size were genetically different between sibling groups within subspecies; age at the inflection point of the growth curve showed most variability between individuals within groups of related siblings. Cross‐breeding experiments showed that the growth parameters in the hybrids were intermediate, providing further evidence for a genetic basis of the observed differences. In this particular case, the between‐subspecies variability reflects genetically adjusted adaptation rather than phenotypic responses to different ecological conditions.

The phenotypic responses of growth to differences in “environment” have been investigated in groups of birds reared under different conditions (hand‐reared v parent‐reared chicks; European v equatorial photoperiod). The rearing method affected only size parameters and not the form of the growth curve of body mass. Significant differences were found for maximum body mass, final body mass and asymptote. Photoperiod had no effect on growth.
Factors affecting recruitment age and recruitment probability in the Western Gull Larus occidentalis
Authors: SPEAR L. , SYDEMAN W. J. , PYLE P.
Published: April 2008

We studied recruitment age (i.e. the age that a gull bred for the first time) and the probability that an adult reproduced during its life in three cohorts of Western Gulls Larus occidentalis breeding on southeast Farallon Island. We examined the effects of sex, hatching date, hatching order, brood size and annual variation in food supply during the recruitment period. Modal recruitment ages of males and females were 4 and 5 years, respectively, a difference that was significant. None of the factors examined, including hatching date, hatching order and brood size, had a significant effect on recruitment age. The probability of breeding in males who experienced low food supply in their fourth and fifth years was lower than that of males who experienced favourable food supply in their fourth and fifth years. Recruitment probability (the proportion of the sample group that recruited among those available to recruit during a given year) of 4‐ and 5‐year‐old males was lower in the food‐poor 1983 El Nino than in years of favourable food supply. The only variable affecting recruitment probability of females was age: recruitment probability was greater among 5‐year‐olds than 4‐year‐olds. Recruitment age in males was more sensitive to annual variation in food supply, probably because females have more difficulty recruiting due to an excess of adult females in the population and because of the different roles in reproduction in which males are primarily responsible for provisioning chicks and maintaining the territory.
The evolution of tail‐length in widowbirds (Ploceidae): tests of alternatives to sexual selection
Authors: SAVALLI UDO M.
Published: April 2008

The long tails of male widowbirds (Euplectes, Ploceidae) have been used to test sexual selection theory, but alternatives to sexual selection have not been investigated. This study tests three alternative hypotheses for the evolution of tail‐length in widowbirds: apose‐matism, the unprofitable prey hypothesis and species recognition. Using museum specimens, geographic patterns of tail‐length were examined for evidence of character convergence (as predicted by the aposematism and unprofitable prey hypotheses) or character divergence (as predicted by the species recognition hypothesis) in areas where two pairs of species were sympatric. There was no consistent trend: one species showed evidence of character convergence and the other some evidence of divergence. Experimental manipulation of tail‐length in the Yellow‐shouldered Widowbird Euplectes macrourus also failed to support the species recognition hypothesis: there was no preference for males with species‐typical tail‐lengths but only a slight and non‐significant trend to favour short‐tailed males. There was also no evidence that mistaken identity led to territory loss following these experimental manipulations. Tail‐length of six Euplectes species did not correlate with unpalatability scores, as predicted by the aposematism hypothesis. These hypotheses do not appear to explain the evolution of long tails in widowbirds, suggesting that sexual selection is the sole factor favouring long tails. Interspecific variation in tail‐length remains unexplained.
Why small cold‐blooded insects pose different conservation problems to birds in modern landscapes
Authors: THOMAS J. A.
Published: April 2008

Butterflies and other insects have declined more rapidly than birds over parts of southwest Europe this century, and early attempts to conserve them often failed. Failure occurred mainly because reserve managers did not cater for three differences in their needs compared with those of vertebrates: (1) Many insects occupy very narrow specific niches within their biotopes, often associated with an ephemeral successional stage; (2) although an insect population can sometimes be supported by a small (<1 ha) patch of its specific habitat, an individual habitat patch may remain suitable for no more than 3–10 years and (3) several insect species are too sedentary to colonize new patches of habitat that arise farther than 300 m‐1 km from old ones during the period that each remains suitable for breeding. Further complications arise from the dependency of some insects on narrow temperature bands, especially in northwest Europe where many species reach their edges of range and are locked into warm, anthropogenic habitats. The same species have broader or different niches farther south, and their habitats may require very different management across geographical ranges. Despite these problems, conservationists have had considerable success in maintaining populations of threatened insects within nature reserves, once knowledge of their ecology and dynamics was applied to site management.
Bird fauna of northeast Asia: a summary of the unique biodiversity and the priorities for conservation
Authors: ANDREEV ALEXANDER
Published: April 2008

The subcontinent of northeast Asia, defined as the region east of the Lena River between 58o and 72oN (and excluding the Kamchatka peninsula), is 3500 km × 1500 km in area (Fig. 1). Influenced by ice‐covered seas, low air temperatures and permafrost, it has a complicated mosaic of habitats, supporting a diverse and unique bird fauna with a number of endemic species and populations.

East of the Verkhoyansk range, the northern limit of continuous coniferous forest retreats southwards and is replaced by two vegetation types unique to northeast Siberia: Larch tundra‐forest (sparse Larix cajanderi) and tall bush tundra ecotone (dominated by the Shrub Pine Pinuspumila and Bush Alder Alnus fruticosa). Shrub Pine dominates sub‐alpine altitudes throughout the interior and coastal ranges, descending in places to sea level.

Coastal habitats include river deltas, brackish water bays, offshore drift ice fields and leads, lagoons, sand spits, marshes, intertidal mudflats, cliffs. offshore islands, upwellings and surface currents. Warmed by the ground water, the permafrost‐free interior valleys support lush deciduous woods of Poplar Popubs suaveolens and Korean Willow Chosenia macrolepis. Higher in the mountains, dry lichen tundra and rocky deserts occur.
Living with relatives: lessons from avian family systems*
Authors: EMLEN STEPHEN T.
Published: April 2008

Family‐dwelling birds provide excellent opportunities for testing evolutionary predictions about social interactions among relatives. Their combination of behavioural complexity with cultural simplicity makes them ideal model systems in which to search for fundamental biological rules of social interaction. In this plenary, I provide a personalized overview of current thinking about both the evolution of families and the social dynamics to be expected among family members. Using an adaptationist/economic approach that uses fitness as its currency, I develop a set of 15 predictions about family formation, family stability, familial cooperation, familial competition and conflict resolution among kin. I argue that knowledge of four basic parameters, genetic relatedness, social dominance, the benefits of group living and the probable success of independent reproduction, can explain many aspects of family life in birds. I further suggest that this evolutionary perspective is generalizable across taxa and will provide new insights into understanding animal family systems in other species, including our own.
A metapopulation approach to the population biology of the Song Sparrow Melospiza melodia
Authors: SMITH JAMES N. M. , TAITT MARY J. , ROGERS CHRISTOPHER M. , ARCESE PETER , KELLER LUKAS F. , CASSIDY ALICE L. E. V. , HOCHACHKA WESLEY M.
Published: April 2008

In this paper, we describe spatial variation in the demography of the Song SparrowMelospiza melodia.Long‐term population studies of birds have generally considered only single sites in optimal habitat, but recent theory has shown the value of taking spatial variation in population dynamics into account. In this theory, collections of local populations in habitat patches connected by dispersal are denned as metapopulations. We review metapopulation models briefly and then use these ideas in a study of the Song Sparrow. Sparrows were studied on islands of varying size and degree of isolation from the North American continent. For analysis, these islands are grouped into three areas. Sparrows on the isolated Mandarte Island usually reproduced and survived well over 17 years but suffered from catastrophic mortality in some winters. After such events, the population recovered quickly without much immigration. Sparrows on smaller islets near Mandarte also survived and reproduced well during 4 years, and they did not experience severe mortality in a winter in which those on Mandarte declined by over 90%. These small islets frequently exchanged first year birds, but only one yearling bird moved between the small islets and the more isolated Mandarte. Sparrows at one of two sites on the larger Westham Island, near the continental mainland, survived less well than on the small offshore islands. Reproduction on Westham Island was poor because of frequent nest failure and high levels of brood parasitism by Brown‐headed CowbirdsMolothrus ater.Despite this poor reproduction and survival, the Westham population remained stable as a result of immigration. We interpret the dynamics of these sparrow populations in terms of H. R. Pulliam's source‐sink metapopulation model.
Field metabolism and water flux of Sociable Weavers Philetairus socius in the Kalahari Desert
Authors: WILLIAMS JOSEPH B. , PLESSIS MORNE A. DU
Published: April 2008

Sociable Weavers Philetairus socius build large communal nests which they occupy year‐round. White et al. suggested that use of this large nest complex significantly reduced the energy expenditure of Sociable Weavers during winter, thus lowering their resource requirements at that time. In this study we have used the doubly labelled water technique to examine the hypothesis that Sociable Weavers have a reduced field metabolic rate during the winter. Further, we measured their water influx and compared our findings with data from other desert‐adapted birds. The field metabolic rate of Sociable Weavers (mean mass = 25.5 g) in the Kalahari Desert in winter averaged 48.7 ± 10.1 kj per day, a much lower energy expenditure than birds of similar size living in more mesic environments. We suggest that this results from a combination of communal roosting and possibly a reduced basal metabolic rate. The water influx of Sociable Weavers averaged 4.6 ml water per day, one of the lowest values reported for a bird of this size. Our analysis indicates that Sociable Weavers cannot rely on seeds as a food source without another source of water because the seeds do not provide enough water to meet their needs.
Seasonal variation in lek attendance and lekking behaviour by male Black Grouse Tetrao tetrix
Authors: BAINES DAVID
Published: April 2008

Eleven Black Grouse Tetrao tetrix leks in the Scottish Highlands were visited at dawn once every week for a year. Apart from July and three leks which were unoccupied in winter, males visited leks throughout the year. Total numbers of males attending leks peaked in March in one study area (six leks) and in April in the second (five leks). The number of males present and the proportion of leks occupied varied seasonally. The proportion of males at leks was at a maximum in April (80% of males) when all leks were attended, with a secondary peak in September when 60% of leks had males present. Males spent the most time displaying in April. The optimal conditions for attendance were calm, dry mornings just after dawn. Most reliable counts of numbers of males were those made between the last week of March and the end of the first week of May.
Patterns of colony attendance in the Cape Petrel Daption capense at Nelson Island, South Shetland Islands, Antarctica
Authors: WEIDINGER KAREL
Published: April 2008

The annual cycle of colony attendance of the Cape PetrelDaption capenseat Nelson Island, Antarctica, covered about 9 months from the start of September until the end of May. Large numbers of birds attended the colony continuously for 6 months from arrival until fledging, except for a 2‐week incomplete pre‐laying exodus when attendance was reduced to 10% of that during incubation. After 1 month (March) of post‐fledging absence, birds returned to the colony for 2 months in numbers comparable to the level in the breeding season. This was followed by a winter absence that lasted only 3 months and was interrupted by two short visits by a small number of birds. Mean attendance was highest during incubation, but short peaks of maximum attendance occurred during the pre‐breeding period. Except for the incubation and brooding periods, colony attendance showed high variability both within and between days. Large numbers of visiting birds occurred on the sea and on islets in front of the colony until the end of October. Unemployed birds constituted an almost constant proportion of up to 50% of colony‐attending birds during the incubation period. Diurnal variability did not show a consistent pattern but may represent preferential feeding during early morning hours, with additional short departures depending on the length of the daylight period. Colony counts were the most consistent during the second half of incubation, when the lowest counts gave an estimate of the number of breeding pairs and peak numbers an impression of the additional number of attending nonbreeders. Pre‐breeding counts revealed the maximum numbers of birds associated with a particular colony. However, for both pre‐ and post‐breeding surveys, several counts a day over a period of at least a week are recommended because of variability in attendance.
Home range and habitat selection by the Nutcracker Nucifraga caryocatactes during autumn in the Alps
Authors: ROLANDO ANTONIO
Published: April 2008

In the Mont Avic Natural Park (NW Italian Alps), the Nutcracker Nucifraga caryocatactes occurred in coniferous forests where Arolla Pines Pinus cembra, its preferred habitat, were absent. A radiotelemetric study carried out during autumn 1992 and 1993 showed that, from September, Nutcrackers concentrated in the few Hazel Corylus avellana hedges of the rural zones of the park to collect nuts, which were eaten or stored. Individual home ranges overlapped to a high degree until October, when birds started to abandon the Hazel areas. From October onward, individual home ranges significantly expanded and their degree of overlap diminished compared to September. The home range analysis and the observations in the field suggested that the population of Nutcrackers in the park during autumn was made up of at least three different categories of birds, which displayed different ranging behaviour patterns. A few untagged birds probably stored nuts in their breeding territories, whereas all the radio‐tagged birds (n = 15) gave no indication of territorial use, since from October they either stored nuts in the coniferous woods near the Hazel hedges or abandoned the park to fly to other Hazel areas. Hence, during autumn the ranging behaviour of the Nutcrackers seems to be largely independent of their reproductive territorial system. Habitat selection analysis and transect counts revealed that birds positively selected Hazels, especially in the coniferous woods around Hazel hedges, and avoided the other coniferous forests. Nevertheless, from October some individuals reversed their habitat choices and positively selected coniferous forests (especially Mountain Pine Pinus uncinata woods) while avoiding Hazel.
Population density and intra‐ and interspecific competition of the African Fish Eagle Haliæeetus vocifer in Kyambura Game Reserve, southwest Uganda
Authors: KRUEGER OLIVER
Published: April 2008

Population density and intra‐ and interspecific competition of the African Fish Eagle Haliæeetus vocifer were studied in Kyambura Game Reserve, southwest Uganda. Density varied significantly between 1.75 and 3.25 individuals per km of shore for the breeding biotopes along the Kazinga Channel and crater lakes and between 0.45 and 0.58 for unsuitable biotopes such as the Kyambura Gorge or the bush grassland. The age‐class distribution showed extremely high percentages of immatures in these unsuitable biotopes (50–95%) as a consequence of intraspecific competition for space and food. Some immatures survived in the bush grassland, feeding on lion and leopard kills and very possibly on birds. Each territory was up to five times larger than breeding pair territories along the Kazinga Channel (5.1 km2 in comparison with 0.9 km2). Interspecific competition for space was likely between immature African Fish Eagles and other species of raptors. Ecological segregation with regard to space was assessed between these species in the bush grassland.
Luxury in freshwater and stress at sea? The foraging of the Common Tern Sterna hirundo
Authors: BECKER P. H. , FRANK D. , WAGENER M.
Published: April 2008

We compared the foraging strategies of Common Terns Sterna hirundo in freshwater (Lake Jeziorsko, Brzeg, Poland) and marine environments (Minsener Oldeoog, German Wadden Sea). Body mass changes, nest relief and duration and number of feeding trips per day were studied by automatically weighing the adults, using electronic balances under the nests. At the freshwater site, adults were lighter both before and after feeding and gained less mass during a trip. in the Wadden Sea, single feeding trips lasted longer than at the freshwater site and the terns made fewer trips per day. To achieve the same mass gain per day as in birds in freshwater, trips at sea had to be longer and food intake per trip was higher. The daily duration of absence for feeding and the daily mass gain were about the same in both areas. The limnetic feeders finished foraging earlier in the evening than the terns foraging at sea. These differences are consistent with the hypothesis that limnetic prey availability was consistent, whereas the tides limited the availability of marine prey. In consequence, foraging over freshwater presents several advantages, such as higher colony attendance, better mate coordination and better parental care.
Systematic and conservation implications of geographic variation in pipits (Anthus: Motacillidae) in New Zealand and some offshore islands
Authors: FOGGO M. N. , HITCHMOUGH R. A. , DAUGHERTY C. H.
Published: April 2008

The New Zealand Pipit Anthus novaeseelandiae occurs as a single species in Europe (as Richard's Pipit), Asia, Africa, New Guinea, Australia and New Zealand. In the New Zealand region, subspecific status has been accorded to allopatric populations on the mainland (A. n. novaeseelandiae), on the Auckland and Campbell Islands (A. n. aucklandicus), on the Antipodes Islands (A. n. steindachneri) and on the Chatham Islands (A. n. chathamensis). Analyses of 23 allozyme loci and morphometric variation of populations on mainland New Zealand and on the Auckland, Campbell, Antipodes and Chatham Islands showed an appreciable and significant divergence between mainland and island populations. The magnitude of the allozyme difference is sufficient to suggest full species designation for the island birds, a conclusion supported by morphometric analyses and in sharp contrast to current taxonomy. However, formal taxonomic change will not be undertaken until the two New Zealand groups have been compared with more distant populations of this wideranging genus. The cryptic variation found in this species has conservation management implications for the small offshore populations.
Incubation pattern and foraging effort in the female Water Pipit Anthus spinoletta
Authors: RAUTER CLAUDIA , REYER HEINZ‐ULRICH
Published: April 2008

Incubation and foraging patterns of female Water Pipits Anthus spinoletta were studied in two breeding seasons in an Alpine valley of Switzerland. Decreased temperature reduced the length of periods spent off the nest (inattentive period), while decreased food availability led to a reduction in time spent incubating (attentiveness), shorter periods spent on the nest (attentive period), more frequent inattentive periods and higher foraging effort, measured as the product of frequency of inattentive periods and twice the flight distance to foraging sites. The negative relation between food availability and foraging effort resulted from more frequent foraging bouts and longer flight distances under poor food conditions. Feeding of the incubating female by the male did not affect foraging effort and attentiveness but did change the temporal pattern of inattentive periods from a few long to several short inattentive periods.
New record, ranging behaviour, vocalization and food of the Madagascar Red Owl Tyto soumagnei
Authors: THORSTROM RUSSELL , HART JULIAN , WATSON RICHARD T.
Published: April 2008

The rare Madagascar Red Owl Tyto soumagnei was captured, radio tagged and released for study in October 1994. It ranged within an area of 210 ha from October to December 1994, and 50% of the locations were along forest edge and newly created tavies, 36% in rice fields and 14% in cultivated tavies. Nine diurnal roost sites were documented in small ravines among secondary vegetation and bananas (Masu sp.). The owl used dense canopy‐covered roosts that averaged 3.7 m above the ground and were extremely close to tavies, averaging 9.8 m. The 17 regurgitated pellets collected contained 27 individual vertebrates representing native small mammals of the families Tenrecidae and Muridae. The owl's vocalization was similar to that of the Barn Owl Tyto alba. This new record on Masoala Peninsula at sea level substantially extends the species potential range in Madagascar, and our observations of behaviour and habitat use contradict previous descriptions of the species as a primary forest obligate.
Predation by Kelp Gulls Larus dominicanus at a mixed‐species colony of Royal Terns Sterna maxima and Cayenne Terns Sterna eurygnatha in Patagonia
Authors: YORIO PABLO , QUINTANA FLAVIO
Published: April 2008

We studied the predator‐prey interaction between Kelp Gulls Larus dominicanus and Royal Terns Sterna maxima and Cayenne Terns Sterna eurygnatha at Punta León, Argentina, from 1990 to 1992. Kelp Gulls were the main predator of tern eggs in all 3 years, accounting for 99% of observed predations (n = 454). A total of 99% of predations occurred on peripheral tern nests. Total predation rate on both tern species was highest in 1990 and varied significantly between years, with between 0.01 and 0.03 cases of predation per hour. Predation rates in all years were significantly higher on Cayenne than on Royal Terns probably because the latter were significantly more aggressive towards gulls than were Cayenne Terns. Royal and Cayenne Terns displayed aggressively towards gulls at least once in 64% and 10% of the observation periods, respectively. Defence behaviour, such as attacking and chasing the predator, was used more frequently by Royal than Cayenne Terns (13.2% v 3.6%). Predation on tern eggs was restricted to only a few Kelp Gulls which nested close to the tern colony periphery, and 50% of the eggs that were stolen were taken by only two pairs during 1991 and 47% by three pairs in 1992. This suggests that the current expansion of the Kelp Gull numbers at Punta León might not necessarily result in a proportional increase in predation rate on both tern species. Stealing eggs from the ground was more successful than from the air (77% v 17%). The nesting strategy shown by Royal and Cayenne Terns at Punta León appears to be an important factor which reduced the impact on their breeding success of high potential predation pressure by gulls.
Body condition, territory ownership and age‐related reproductive performance in Spruce Grouse Dendragapus canadensis hens
Authors: REYNOLDS JIM
Published: April 2008

Adult Spruce Grouse Dendragapus canadensis hens show better reproductive performance (i.e. larger clutch size, earlier clutch initiation, higher frequency of renesting) than year‐lings. Body and breast muscle weights, condition indices and relative body composition were compared between adult and yearling birds from northeastern Ontario, Canada, to determine whether differences in endogenous reserves mobilized for egg production and (or) territory ownership could explain these differences in reproductive performance. Adults and yearlings showed similar declines in body‐weight, breast muscle weight and condition indices from the pre‐laying to the post‐laying period, but no significant interage differences emerged at any stage of the breeding season. Changes in body composition, especially gut structure, were similar in all birds; this result is consistent with a dietary shift in both age classes from a fibrous winter diet to more succulent foods in spring. Non‐territory‐holding (replacement) yearlings also had similar body‐weights and breast muscle weights and were in similar condition to territory holders (residents) in the pre‐laying period. My findings do not support the hypothesis that differences in body condition and territory occupancy can account for differences in age‐related reproductive performance in Spruce Grouse.
Does loss of mass during breeding correlate with reproductive success? A study on Blue Tits Parus caeruleus
Authors: GEBHARDT‐HENRICH SABINE G. , HEEB PHILIPP , RICHNER HEINZ , TRIPET FRæDæRIC
Published: April 2008

Substantial loss of mass of female Blue Tits Parus cueruleus during breeding is commonly explained by three not mutually exclusive explanations: shrinking of gonadal tissues, cost of reproduction and adaptation to save energy during flight. This study showed that loss of body mass was inversely correlated with reproductive success of individual females. Female tarsus length and timing of breeding correlated with loss of body mass, whereas ectoparasite loading had no significant effect on body mass. Loss of body mass during the rearing of young could be a useful measure of cost of reproduction by accounting for individual variation in female quality.
Territory structure of the Robin Erithacus rubecula outside the breeding season
Authors: JOHNSTONE IAN
Published: April 2008

On the basis of radio‐tracking data from 51 individuals, the space use of Robins Erithacus rubecula outside the breeding season was non‐uniform and multinuclear. On average, territorial Robins spent 78% of their time in one or more resource patches represented by bushes, which accounted for only 1% of a convex polygon encompassing each range. A suite of range polygons was developed to quantify range structure. One of these polygons showed similar size to, and high overlap with, defended‐area polygons and so was a good estimate of territory. In addition, the area of bushes in each polygon suggested Robins occupied constant resource territories. There was undefended neutral ground between territories, which, although seldom visited, was crossed to achieve intrusions. Over the short term (days), Robins showed high fidelity to the resource patches they defended. Over the longer term (months), most individuals showed some degree of range shift. It is concluded that if the information concerning territories is to be maximized, empirically derived sampling protocols should be used when measuring territory parameters.
Age‐related effects of a nonbreeding event and a winter wreck on the survival of Shags Phalacrocorax aristotelis
Authors: HARRIS M. P. , WANLESS S. , ELSTON D. A.
Published: April 2008

During 1993, about half the adult Shags Phalacrocorax aristotelis alive on the Isle of May, southeastern Scotland, failed to breed. The proportion not breeding was highest (66%) for individuals aged 14–21 years and lowest (12%) for those aged 3–6 years. In February 1994, a prolonged spell of onshore winds resulted in a wreck of these adults such that overwinter survival was reduced from the normal 88% to 14.7%. The age‐specific pattern of survival over this winter differed from previous years, with birds aged less than 7 years and more than 16 years surviving less well and middle‐aged individuals surviving better than expected. Whether an individual had bred or not in 1993 had little effect on the chances of survival of the youngest and oldest individuals, as most died. However, among Shags aged 12–15 years, those which had bred survived markedly less well than those which had not, indicating that there had been some cost involved to birds in breeding in 1993.
The foraging behaviour of Little Penguins Eudyptula minor at different light levels
Authors: CANNELL BELINDA L. , CULLEN J. M.
Published: April 2008

The role of vision in the prey‐catching behaviour of Little Penguins Eudyptula minor was tested using four captive penguins in a swimming pool. A live fish was placed in the pool with a penguin at various light intensities before and after dawn and dusk. The penguins' behaviour in the morning was the same as in the evening. As the light decreased, the percentage of fish chased by the penguins decreased, and no fish were caught at a light level less than 0.01 μeinstein/m2/s (which occurs approximately 25 min before sunrise and after sunset at latitude 37d̀S). The time the penguins spent searching for the fish also decreased with decreasing light. The probability of a penguin pursuing a fish was found to be dependent on the amount of light, such that log,(p/1 ‐ p) = 6.323 + 2.08 × log,(light level), where p= the probability of pursuing a fish.
Seasonality of a forest bird community in Hong Kong, South China
Authors: KWOK H.K. , CORLETT RICHARD T.
Published: April 2008

We studied the composition of a secondary forest bird community in Hong Kong (22°N) between December 1992 and June 1995, using the variable point count method. The visual detectability of each bird species had a significant positive relationship with body length. A total of 71 bird species was recorded but three resident habitat‐generalists, the Great Tit Parus major, Light‐vented Bulbul Pycnonotus sinensis and Japanese White‐eye Zosterops japonicus, accounted for 65% of the mean total bird density of 38 per ha. The number of species seen was highest between December and April and lowest from July to September, but the total bird density was highest between December and June and lowest from August to September. The main breeding season was from March to August. Insectivores and insectivore‐frugivores accounted for 80% of the species and 98% of the total bird density. The percentages of migrant species and individuals are similar to those reported at equivalent latitudes in North America. Bird community diversity and composition differed considerably from that of larger, older forest areas in South China, presumably as a result of differences in forest age, area and isolation.