bluuebunny/crossref_metadata_2025 huggingface dataset:
Chick loss in the Falkland Skua Catharacta skua antarctica
Authors: LAMEY CAMELIA SYKES
Published: April 2008

Data on reproductive success of 110 Falkland Skua Catharacta skua antarctica pairs were gathered during the austral summers of 1988–1989 and 1990–1991 on New Island, Falkland Islands. Adults laid two eggs 2–3 days apart and began incubation with the first egg. For the years combined, 1.39 chicks per nest hatched and 0.84 chicks per nest fledged (fledging was defined as surviving to 16 days of age). Brood reduction was common; 43% of the two‐chick broods were reduced to one, and mortality was concentrated on the younger chick. Although asynchronous hatching and differential death are consistent with Lack's brood reduction hypothesis, application of O'Connor's quantitative criterion revealed that sibling competition may not be responsible for the observed chick mortality. Furthermore, because no aggressive interactions between chicks were observed or detected indirectly, siblicide may be absent in this population. Instead, predation modified by a variety of factors may have led to the greater mortality of the second‐hatched chick.
The timing of breeding and offspring size in Great Tits Parus major
Authors: CICHON MARIUSZ , LINDÉN MATS
Published: April 2008

The relationship between the timing of breeding, offspring weight and offspring recruitment was investigated in two populations of Great Tits Parus major. In two of six seasons a significant negative correlation was found between laying date and fledgling weight, in three seasons the opposite was true and in one season no significant correlation existed between these variables. Offspring recruitment was quantified in five seasons, and late‐nesting birds were found to produce significantly fewer recruiting offspring in two of these, the same two seasons when late fledglings had significantly lower weights. No significant correlation existed between the number of recruits and laying date in the three seasons when late fledglings were as heavy as or heavier than early fledglings. The potential detriment to reproductive success of lateness thus was offset when late‐nesting parents managed to produce heavy young. Between‐year variations in the seasonal pattern of reproductive success has previously been suggested to contribute to the maintenance of variability in the timing of breeding in Great Tits. In this paper we suggest that producing heavy offspring late in the season might be a proximate factor influencing the seasonal patterns of reproductive success. Producing heavy offspring late in the season is probably not a “strategy” but rather an effect of chance differences between years in the seasonal availability of food or the seasonality of other factors important for the nesting birds.
Some male Pied Flycatchers Ficedula hypoleuca in Iberia become collared with age
Authors: POTTI JAIME , MERINO SANTIAGO
Published: April 2008

The development of a collar in Pied Flycatchers Ficedula hypoleuca in Spain is described and its ontogenetic and genetic variation and phenotypical correlates are analysed. Collared males were older than males having traces of collar or lacking one. Also, males showing a collar or trace of a collar had larger white forehead patches than those lacking a collar. Intrapopulation variation in both collar expression and white patch size, which might be genetically determined but phenotypically decoupled in temporal expression, resembles between‐species variation among the black and white European flycatchers.
The Nene Branta sandvicensis Recovery Initiative: research against extinction
Authors: BLACK JEFFREY M.
Published: April 2008

Since 1960, about 2150 Hawaiian Geese or NeneBranta sandvicensiswere reintroduced in Hawaii to supplement the remaining wild population of about 30 birds. These geese were released mostly in high mountain sanctuaries. These sites became unsuitable during prolonged drought and the few surviving birds were those which had moved away from the release sites. The geese that survived had moved to, or were released near, agricultural pasture land. About 600 Nene are currently living in the wild; numbers are declining on the island of Hawaii, stable on Maui and increasing on Kauai. Management priorities include enhancement of grasslands, predator control and maximizing genetic diversity. To enable the species to recover, management will probably have to be large scale, intensive and prolonged. Further released captive‐bred or translocated Nene should have access to enhanced habitats after predators have been controlled.
Management of threatened bird species: evaluation of the hands‐on approach
Authors: CADE TOM J. , TEMPLE STANLEY A.
Published: April 2008

Intensive manipulations of rare birds can be important conservation tools when traditional management practices, such as legal protection and habitat preservation, are insufficient to halt population declines and save endangered species from extinction. Nonetheless, this “hands‐on” methodology has been criticized as scientifically unsound, ineffective, costly and a diversion from preservation of habitats and ecosystems. We consider the effectiveness of manipulative management by reviewing 30 presentations at the Symposium on Management Techniques for Preserving Endangered Birds in 1977. Examination of the outcome of these efforts in 1993 indicates that 43% have contributed to improved population viability through an increase in breeding numbers, another 23% have helped to stabilize numbers or to slow the rate of population decline, while the outcome of five others (17%) is inconclusive, and the same number ended in failure. Our evaluation of these and other similar projects is that the hands‐on approach has proved to be a justified and effective stopgap procedure to help critically endangered species through a crisis, to reintroduce species into previously occupied range and to reinforce locally diminished populations. As such, it often needs to be part of an integrated program for avian conservation.
Impacts of disturbance on migratory waterfowl
Authors: MADSEN JESPER
Published: April 2008

It is well known that disturbance from human activities can cause temporary changes in behaviour and locally affect temporal and spatial distribution of migratory and wintering waterfowl. But it is also known that, to some extent, birds can compensate for disturbance by altering their behaviour or habituating to human activities. Comparatively little is known about how these reactions to disturbance may impact on the large‐scale dispersion of waterfowl and, ultimately, on their population dynamics. To be able to answer these questions, a better theoretical framework, based on optimal foraging theory incorporating predation risk, and field experiments are required. Furthermore, we need to study the waterfowl throughout their winter ranges to interpret the overall impacts of disturbance. This paper examines two cases where the impacts of disturbance have been assessed from field experiments. In one study, disturbance effects of shooting were tested by setting up experimental reserves in two Danish coastal wetlands. Over a 5‐year period, these became two of the most important staging areas for coastal waterfowl, and the national totals of key species were significantly increased. A national management plan which will establish more than 50 new shooting‐free refuges on Danish coastal areas within the next 5 years is likely to boost waterfowl numbers even more. Such retention of birds at more northerly sites on the fiyway should result in a more efficient resource utilization and may positively affect the population dynamics where numbers are affected by winter resources. In a second study, the impacts of disturbance by farmers on spring fattening of Pink‐footed Geese Anser brachyrhynchus were analysed. In undisturbed areas in northern Norway, abdominal profiles of the geese increased rapidly, whereas in disturbed sites they did not. Subsequently, geese that had used undisturbed sites reproduced better than geese from disturbed sites.
The ecology of the avian brain: food‐storing memory and the hippocampus
Authors: KREBS JOHN R. , CLAYTON NICKY S. , HEALY SUSAN D. , CRISTOL DANIEL A. , PATEL SANJAY N. , JOLLIFFE ANNA R.
Published: April 2008

Some species of birds store food, often hoarding several hundreds of seeds over a period of just a few weeks. Field and laboratory studies have demonstrated that food‐storing species have an impressive memory and an enlarged region of the brain, the hippocampal region. Lesion experiments have shown that the hippocampus is important in accurate retrieval of stored food. Taken together, these results have led to the hypothesis that the enlarged hippocampus is associated with the memory requirements of retrieving stored food. In this review, we discuss four areas of study: comparative studies of the brain, comparative studies of behaviour, developmental plasticity and seasonal changes in food storing and the hippocampus.
Circannual clocks in avian reproduction and migration
Authors: GWINNER EBERHARD
Published: April 2008

Many behavioural and physiological functions of organisms are adjusted to the periodic changes in their environment, particularly to those related to the natural day and year. This adjustment is often achieved through the action of endogenous daily (circadian) and annual (circannual) clocks. Studies of the control of avian moult, migration and reproduction have played a major role in understanding how biological clocks function and interact with rhythms in the environment. Investigations on tropical birds such as the East African subspecies of the Stonechat (Saxicola torquata axillaris) and long‐distance migrants like the Garden Warbler (Sylvia boriri) have provided the longest records of circannual rhythms, some of them running for more than 12 years, with periods ranging from about 9 to 13 months. Avian circannual rhythms are organized in a characteristic way for a particular species or population, and cross‐breeding experiments have shown that some of the differences found among them are genetically determined. In African Stonechats circannual rhythms guarantee that seasonal events occur at the appropriate times of the year and in the characteristic sequence. They also control a “reproductive window” that provides the temporal framework for breeding. The width of this window is rather inflexible but the performance of a bird within this framework (e.g. whether it breeds once or twice per season) is subject to modification by environmental conditions. In migratory birds circannual programs are involved in determining the time course, distance and direction of migration. Circannual rhythms are synchronized with and modified by environmental factors in a complex way, but the endogenous mechanisms usually respond to environmental cues such that an optimal adjustment to season and latitude is guaranteed.
The magnitude and timing of migration by soaring raptors, pelicans and storks over Israel
Authors: LESHEM YOSSI , YOM‐TOV YORAM
Published: April 2008

The magnitude and timing of the autumn and spring migrations of 35 species of medium‐and large‐sized raptors, White Pelicans Pelicanus onocrotalus and White Storks Ciconia ciconia were studied in Israel. Observations were carried out from the ground by a line of observers covering most of the width of Israel across the line of migration and by radar. There was a high correlation between the counts obtained by ground observers and by radar. On average, about half a million raptors (mainly Lesser Spotted Eagles Aquila po‐marina, Honey Buzzards Pernis apivorus and Levant Sparrowhawks Accipiter brevipes), 250,000 White Storks and 70,000 White Pelicans passed during autumn, and about a million raptors (mainly Honey Buzzards, Steppe Buzzards Buteo vulpinus, Steppe Eagles Aquila nipalensis and Black Kites Milvus migrans) and 450,000 White Storks passed during spring. Peak numbers were higher–over a million raptors and half a million White Storks. There was high interyear variation in the number of migrants recorded during the study, probably caused by weather and counting efforts. For some species, the whole world (Lesser Spotted Eagle and Levant Sparrowhawk) or Palaearctic (White Pelican) population passes over Israel during migration, allowing an estimate of the world populations of these species. Mean dates of arrival of most raptors are highly predictable, with confidence limits ranging between 1.5 and 5.5 days. The migration periods of White Storks and White Pelicans are longer and their mean day of appearance is less predictable (confidence limits range from 4.2 to 13.8 days). During autumn, 90% of the migrating populations of nocking species, such as Levant Sparrowhawk, Lesser Spotted Eagle, Honey Buzzard and Red‐footed Falcon Falco vespertinus, pass within 13, 15, 16 and 18 days, respectively, while nonflocking species, such as Egyptian Vulture Neophron percnopterus, Marsh Harrier Circus aeruginosus and Short‐toed Eagle Circaetus gallicus, generally take twice as long to pass. Similar passage periods were recorded in spring. For most species, the autumn migration period was longer than the spring migration period, probably because in autumn adults move before the young birds. Three factors affected the timing and spread of the migration wave: age at first breeding, diet and size of the breeding area.
Taxonomy of the Houbara Bustard Chlamydotis undulata subspecies considered on the basis of sexual display and genetic divergence
Authors: GAUCHER PHILIPPE , PAILLAT PATRICK , CHAPPUIS CLAUDE , JALME MICHEL SAINT , LOTFIKHAH FATEMEH , WINK MICHAEL
Published: April 2008

The Houbara Bustard Chlamydotis undulata is a polytypic species with three subspecies classified according size, colour and distribution: C. u. undulata, C. u. fuertaventurae and C. u. macqueenii. A comparative study of the male display behaviour of these three subspecies has shown similarities between C. u. undulata and C. u. fuertaventurae, whereas appreciable differences exist in the visual and auditory aspects of the display between C. u. undulata and C. u. macqueenii. These observations make the current taxonomy of Houbara Bustard questionable, particularly in view of the major importance of the sexual display in bird speciation processes. Furthermore, DNA analysis of the cytochrome b gene indicates the existence of a significant differentiation between the C. u. undulata and C. u. macqueenii populations. These findings indicate the need for a revision of the taxonomy of genus Chlamydotis which should separate the macqueenii and undulata populations at species rank. Until further investigations are completed, C. u. fuertaventurae should be kept as a subspecies of undulata since the courtship display is alike in both populations.
The contribution of artificial nest experiments to understanding avian reproductive success: a review of methods and conclusions
Authors: MAJOR RICHARD E. , KENDAL CAITLIN E.
Published: April 2008

Artificial nest experiments have been used in approximately 80 recent studies to identify a wide range of factors influencing reproductive success of birds. Despite the same factors being examined in different studies, few consistent patterns have emerged from these experiments. Analysis of reproductive success at artificial and natural nests reveals that reproductive success measured with use of artificial nests is frequently underestimated. In addition, several studies suggest that different species of predators may be differentially attracted to the two types of nest. These results call the utility of artificial nests into question as a tool for elucidating factors influencing the success of natural nests. Analysis of the methodology used in artificial nest experiments reveals that in general there is poor correspondence between the appearance of experimental setups and the natural systems they attempt to model. If future experiments with artificial nests are to contribute to theory, the quality of experiments must improve and the assumptions underlying the artificial approach must be tested. Collecting this information will be relatively simple compared with the time‐consuming task of experimenting with natural nests. Until these data are collected, conclusions about nesting ecology derived from the use of artificial nest experiments should be treated as preliminary.
Breeding biology during establishment of a reintroduced Griffon Vulture Gyps fulvus population
Authors: SARRAZIN FRANÇOIS , BAGNOLINP CONSTANT , PINNA JEAN LOUIS , DANCHIN ETIENNE
Published: April 2008

We studied the breeding parameters of a reintroduced population of individually marked Griffon Vultures Gyps fulvus in the Grand Causses region of southern France from the time of first reintroduction in 1982 to 1992. Among nesters, 65% of the birds released as immatures or born in the wild recruited into the breeding population when 4 years old, i.e. 1 year earlier than previously described. The proportion of birds nesting each year was relatively high and increased with time, suggesting that conspecific attraction favoured recruitment. We detected a permanent adverse effect of long‐term captivity on the nesting success of birds released when more than 2 years old: compared to the natural population, birds which had been kept in captivity showed a reduced breeding success during the whole study period. The breeding success of released immatures and wild‐born birds was similar to the highest values observed in a natural population in the Spanish and French Pyrenees. Breeding failures did not usually result in mate change but affected nest‐site fidelity. Birds not born in the wild were more likely to recruit to the largest subcolonies available, which highlights the role of social attraction. The observed philopatry of wild‐born birds probably resulted from such a social attraction since most of them were born in the largest subcolony. Conspecific attraction maintained the spatial aggregation of nests, whereas nest changes after a breeding failure favoured the spatial expansion of the colony.
Population trends in Kittiwake Rissa tridactyla colonies in relation to tick infestation
Authors: BOULINIER THIERRY , DANCHIN ETIENNE
Published: April 2008

Parasite and disease transmission has long been considered one of the main costs of group living, but there is still little empirical evidence. Most seabird species breed in dense colonies and occupy the same breeding sites for many years and thus could be exposed to deleterious levels of haematophagous ectoparasite infestations. The aims of this study were to provide information on the epidemiology of the tickIxodes uriaeand to investigate the relationship between KittiwakeRissa tridactylacolony population trends and local levels of tick infestation in chicks. It is based on a cross‐sectional survey of a large sample of British Kittiwake colonies (22 colonies more than 30 years old and situated on natural cliffs).Ixodes uriaewas by far the most common ectoparasite detected and was found in all colonies examined. Ticks were aggregated between nests, but not between siblings. Very young and old chicks were far less parasitized than chicks of intermediate age and were excluded from the analysis. Among colonies for which we had good data on population trends in Kittiwakes, those decreasing in number had a higher prevalence and density of ticks than those which were increasing. We suggest that this correlation reveals a cause‐and‐effect relationship. By influencing the local reproductive success, ectoparasites can affect the recruitment of new breeders and the breeders' site fidelity in the following year, thus influencing the local trend of numbers. This causal link highlights the potential effect of parasites on their host population and thus needs to be investigated further.
Breeding time, food supply and fitness components of Blue Tits Parus caeruleus in Mediterranean habitats
Authors: Dias Paula C. , Blondel Jacques
Published: April 2008

We analysed the relationship between the timing of food availability and within‐season variation of both reproductive success and nestling body size of Blue Tits Parus caeruleus in Mediterranean habitats. Synchronization between food supply and reproduction was expected to be positively related to fitness components. We measured deviation from maximum food supply using a parameter that we called “time‐lag”, which quantifies the degree of synchronization between the date of maximum food requirements by the nestlings and the date of maximum caterpillar supply in the habitat. This parameter was expected to be related to reproductive success as measured by the number and body‐condition of fledglings. The predictions were that time‐lag should be negatively correlated with the proportion of nestlings raised to fledging and the size of the fledglings. These predictions have been tested in different types of habitat. The results demonstrate that caterpillar supply during a critical nestling period can have a strong influence on fitness components. As predicted, synchronization with caterpillar supply is positively related to the number and body size of fledglings. Since there is large between‐habitat variation in the timing of food supply, the key issue seems to be the adjustment to local patterns of food availability.
Breeding biology and seasonal abundance of Lappet‐faced Vultures Torgos tracheliotus in western Saudi Arabia
Authors: Newton Stephen F. , Newton Anne V.
Published: April 2008

Lappet‐faced Vultures Torgos tracheliotus utilizing a 2200‐km2, fenced, protected area in western Saudi Arabia were studied over 4 years. Numbers fluctuated seasonally from minima of c. 30 individuals in the spring to maxima of 160 birds in the autumn. All birds foraged predominantly on domestic livestock carrion outside the Reserve. In each year, up to 17 pairs attempted to breed, with 81% of pairs laying eggs, typically in large Maerua crassifolia trees. In all, 81% of the eggs hatched and 85% of nestlings fledged. Most eggs were laid in December, when mean daily air temperatures were lowest, and young usually fledged c. 180 days later. Overall, 56% of nesting attempts fledged young. Juvenile mortality over the first 3 months after fledging was at least 17%. The numbers and proportion of breeders appeared to be stable, but it is not known whether the establishment of the Reserve concentrated the nesting and roosting of vultures in the area or has attracted birds from elsewhere. Breeding success was higher than in most well‐studied African populations and probably those nesting elsewhere in Arabia. Four pairs reared 52% of the fledglings observed in the Reserve over 4 years. The Saudi Arabian Lappet‐faced Vultures probably belong to the subspecies negevensis and, because of the extinction of this subspecies in the wild in Israel, the well‐being of the Saudi Arabian population is critical to the subspecies' conservation.
Territory strategy of the migratory Brown Shrike Lanius cristatus
Authors: SEVERINGHAUS LUCIA LIU
Published: April 2008

Brown Shrikes Lanius cristatus are both transients and winter residents in Taiwan. Large numbers of birds crowd into the available habitat during the transient period, and the cost of maintaining territories changes greatly, depending on the number of shrikes present. This study examined how wintering Brown Shrikes adapt to the changing level of competition in territory establishment. About 24% of autumn transients arrived before any wintering birds, while 73% of wintering birds arrived during autumn transient time. The frequency of aggression recorded was significantly related to the number of birds seen along the transect line that day. Among ringed birds that returned during transient time, 80% returned directly to their previous territories, but some waited for the departure of transient birds before establishing territories. Territory compression occurred at high population densities. Departure from and arrival at the study area were frequent during the winter, but no birds moved territories within the study area. On average, 25% of ringed wintering shrikes returned to the study site in the subsequent years, while no transients returned. This low site tenacity may be. in part, a result of a high persecution rate along the migration route.
Geographic variation in breeding parameters of the Pied Flycatcher Ficedula hypoleuca
Authors: SANZ JUAN JOSÉ
Published: April 2008

Variation in laying date, clutch‐size and number of fledglings of the Pied Flycatcher Ficedula hypoleuca was studied in relation to altitude, habitat and latitude, using data from 99 breeding areas from 35d̀ N to 70d̀ N. Laying date significantly increased with altitude and showed a significant quadratic relationship with latitude, with the earliest values at about 50d̀ N. This quadratic relationship shows the same pattern as the relationship between arrival time of adults on the breeding areas and latitude. Clutch‐size variation was significantly related to altitude and habitat, small clutches being laid at high altitude and in coniferous forests. Number of fledglings was significantly affected by habitat type, with lower values in the coniferous than in the deciduous forest. Mean clutch‐size and mean number of fledglings showed the same quadratic relationship with latitude. In contrast to some earlier studies, an increased clutch‐size with latitude was found, mainly because of new data from areas in the southern part of the species' distribution.
Impact of food abundance, diet and food quality on the breeding of the fruit pigeon, Parea Hemiphaga novaeseelandiae chathamensis, on Chatham Island, New Zealand
Authors: POWLESLAND R. G. , DILKS P. J. , FLUX I. A. , GRANT A. D. , TISDALL C. J.
Published: April 2008

Breeding and diet of Parea Hemiphaga novaeseelandiae chathamensis were studied in relation to food abundance and quality on Chatham Island from 1991 to 1994. Although pairs were found breeding in all months, they nested predominantly during winter and spring (June‐November). The timing of the nesting season, the proportion of pairs that bred and the number of chicks reared per pair varied between nesting seasons. During the 1992–1993 and 1994–1995 nesting seasons, all pairs nested, and many pairs reared two chicks, often involving clutch overlap (58% of 12 cases in 1992–1993, 37% of eight cases in 1994–1995). In 1993–1994, when fruit was scarce, nesting began 2 months later, only 44% of pairs nested and no pairs attempted to rear a second chick. Prior to and during the productive nesting seasons (1992–1993, 1994–1995), the diet of Parea consisted mainly of fruit, particularly that of Matipo Myrsine chathamica in autumn (March‐May) and Hoho Pseudopanax chathamicus in winter and spring. Nutrient analyses of the main Parea foods showed that the pulp of these fruit were rich in lipids and available carbohydrates compared with those in foliage foods. Heavy fruiting of Matipo and Hoho promoted early nesting and prolonged nesting for 6 months, including nesting during winter.
Breeding ecology of Styan's Bulbul Pycnonotus taivanus in Taiwan
Authors: HSU MINNA J. , LIN YAO‐SUNG
Published: April 2008

The breeding ecology of Styan's Bulbul Pycnonotus taivanus, an endemic species in Taiwan, was studied in Kenting, Taiwan. The duration of the breeding season of Styan's Bulbul stretched from March to July in 1983. The average clutch size was 3.3 eggs (n=34), and hatching success was 60%. The average number of nestlings at hatching was 2.7 per clutch, and 73% of the young fledged. Styan's Bulbuls selected their nest sites among dense vegetation. In the study area, 75% (n=84) of nests were found in the Indiapoon Beautyleaf tree Calophyllum inophyllum, which had a relative vegetation density of only 33.5%. Factor analysis was used to analyse 13 nest‐site characteristics of 63 nests, and five factors accounted for 69% of the variation.
Mass and date at departure affect the survival of Ancient Murrelet Synthliboramphus antiquus chicks after leaving the colony
Authors: GASTON ANTHONY J.
Published: April 2008

I compared the timing of colony departure and body mass of 53 Ancient Murrelet Synthliboramphus antiquus chicks that were retrapped as adults in Haida Gwaii, British Columbia, with those of 3992 chicks not retrapped. If the probability of recapture is a measure of survival, survival was related to both mass and date. Chicks that left the colony at 26 g or less had a lower chance of survival than heavier chicks, and those that left after the median date of departure survived better in some years than those that left earlier. The effect of date was not related to a seasonal change in departure mass because chick mass declined with departure date. I suggest that, because of heavy adult mortality during breeding, the timing of breeding in the Ancient Murrelet is based on a compromise between the optimum dates for chick and adult survival. This is in contrast to evidence from other, nonprecocial, seabirds.
Blackaps Sylvia atricapilla stopping over at the desert edge; physiological state and flight‐range estimates
Authors: IZHAKI IDO , MAITAV ASAF
Published: April 2008

Migrating Blackcaps Sylvia atricapilla were mist netted at the desert edge in northern Israel and in Elat (southern Israel) during spring and autumn migrations between 1970 and 1991. Birds in spring in northern Israel were representative of birds that had completed the crossing of the Sahara, while those in Elat still had to cross the 150 km of the Negev Desert, which separates Elat and northern Israel. In autumn, birds captured in northern Israel were representative of those about to cross the Sahara Desert, while those in Elat had already started to cross the desert. The data allowed analysis of seasonal and location differences in the physiological state of Blackcaps before and after crossing the Sahara. Data analysed included body mass, visible fat score and calculated fat content. Autumn migrants were in better physiological condition than spring migrants at both locations, probably as a consequence of their migration route through fertile areas in autumn compared with the crossing of the Sahara in spring. Body mass was less variable after the Sahara crossing in spring than before the crossing in autumn. In spring, 71% and 67% of the birds were fat depleted (fat scores 0 and 1) at Elat and in northern Israel, respectively, while in autumn 34% and 42% were fat depleted. Blackcaps at Elat were 1.6 g lighter than those in northern Israel in autumn and 1.9 g lighter in spring. Potential flight ranges were estimated on the basis of meteorological conditions and flight altitude of passerines above the Negev in Israel (northern Sahara edge) during migration and on a simulation model that considered both energy and water as potential limiting factors for flight duration and distance. The simulation model predicted that half of the Blackcaps that stopped over in Elat and the majority of those that stopped over in northern Israel could not make a nonstop flight over the Sahara Desert in autumn without the assistance of at least an 8 m per s tailwind. Such a wind would still not be sufficient for 34% of the birds in Elat and 42% in northern Israel, and clearly they had insufficient fat reserves to cross the Sahara in a single flight. Although the fattest Blackcaps had accumulated sufficient fat to enable them to traverse the Sahara in a single flight, they probably faced dehydration by at least 12% of their initial body mass when they reached the southern Sahara edge. These birds should use intermittent migration with stopovers at sites with drinking and feeding potential. Their decision to stop over during the day in the desert at sites with shade but without food and water would be beneficial if the meteorological conditions during daytime migration imposed greater risks of dehydration than at night. Spring migrants could not reach their breeding areas in Europe without feeding, but those examined in Elat could cross the remainder of the desert in a single flight.
Behaviour in the post‐nestling dependence period of radio‐tagged Common Buzzards Buteo buteo
Authors: TYACK A. J. , WALLS S. S. , KENWARD R. E.
Published: April 2008

Behaviour of 26 young Common Buzzards Buteo buteo was studied by systematic radiotracking during July and August 1991. After hatching between 11 May and 18 June, the young buzzards fledged when they were 43–54 days old. Distances travelled from the nest increased abruptly after birds were 65 days old, when their flight feathers had completed growth: buzzards were located more than 500 m from the nest in only 2% of records within 65 days of hatching but in 26% of records when they were older. Before their 65th day, there was an increase with age in distance from the nest, time spent flying and time spent calling, especially for buzzards with continuous woodland around the nest. The increases in distance and areas covered were greatest for broods where parents were most often present, which was at nests with the most grass and arable farmland nearby. Between their 65th and 100th days, buzzards showed no increase in activity with age and called less, especially where there was extensive woodland, and travelled farthest from nests with least neighbouring grassland; broods with few young most often had parents nearby. Young buzzards associated strongly with each other between leaving the nest and completing feather growth, but some broods later became much less cohesive. Variation in activity was not linked to sex or to the presence of 30 g back‐pack radio‐tags compared with 12‐g leg‐mounted radio‐tags.
The effect of body condition on the cost of reproduction in female Collared Flycatchers Ficedula albicollis
Authors: CICHOŃ MARIUSZ , OLEJNICZAK PAWEL , GUSTAFSSON LARS
Published: April 2008

Survival of females in relation to their body condition was investigated in the Collared Flycatcher Ficedula albicollis on Gotland, Sweden. The brood size was manipulated by enlarging or reducing the number of nestlings by one or two chicks. We found a positive relationship between experimental treatment and the condition of the female in the year of the experiment. Among females which disappeared (had apparently died) between years, the relationship was negative but not significant. When the effect of brood manipulation on the probability of survival was analysed separately for females in poor and good body condition, a negative relationship between experimental treatment and probability of survival among females in poor condition was found. This result indicates the existence of a cost of reproduction in terms of survival in low quality females. There was no effect of brood manipulation on the survival of females in good body condition. Our analyses suggest that individuals have different costs of reproduction, depending on their conditional state.
Phylogeny of the nuthatches of the Sitta canadensis group and its evolutionary and biogeographic implications
Authors: PASQUET ERIC
Published: April 2008

A phylogeny of ten species of nuthatch (Sittidae), including the newly described Kabylie Nuthatch Sitta ledanti of North Africa, was constructed using a sequence of 491 bp of the cytochrome‐b gene of mtDNA. On the basis of trees derived using parsimony analysis and neighbour‐joining methods, and assessments of robustness based on bootstrap analysis, the following phylogenetic relationships were inferred: the five species of the Sitta canadensis group are a monophyletic group, within which S. canadensis, S. whiteheadi and S. villosa form the sister clade of S. krueperi and S. ledanti; the other relations are not so well supported. These phylogenetic relationships are congruent with morphology. Differences in behavioural and ecological characters as well as biogeographic patterns are discussed.
Biogeography and history of the Mediterranean bird fauna
Authors: COVAS RITA , BLONDEL JACQUES
Published: April 2008

With 366 species of breeding birds, the Mediterranean region is a “hot spot” of species diversity. Many biogeographic realms contributed to the establishment of the extant fauna, which makes this region a crossroads for birds, but the two most important realms are the large forest blocks that extend today over Eurasia and the semi‐arid belts of the southern and southwestern Palaearctic. The few groups that presumably differentiated within the Mediterranean basin are mostly birds of open habitats and shrublands (e.g. Sylvia spp.), whereas few species evolved in Mediterranean forests dominated by sclerophyllous evergreen tree species. We suggest this results from the history of vegetation belts and their associated faunas during the Pleistocene. On the whole, in contrast to other groups of vertebrates, the bird fauna is fairly homogeneously distributed all over the basin although there are some regional‐specific trends in species assemblages, mostly on the basis of habitat selection and biogeographic origin. Many species of eastern and southeastern origin invaded the Mediterranean basin on the northern side of the sea up to the Balkan peninsula and the southern side to the Atlantic coast. The extant biogeographic patterns of the Mediterranean bird fauna are interpreted in the light of the Quaternary history shared by the biotas of the western Palaearctic in relation to the cycle of climatic changes which produced periodic huge spatiotemporal migrations of communities and populations. The severe human impact that started c. 8000‐10,000 years ago resulted not so much in species extinctions as in dramatic changes in distributional patterns, complicating the reconstruction of biogeographic scenarios.
The hummingbird community of a lowland Amazonian rainforest
Authors: COTTON PETER A.
Published: April 2008

Between October 1987 and September 1989, the British Ornithologists' Union Colombia Expedition recorded 16 species of hummingbird at Matamatá in the Amacayacu National Park, Amazonas, Colombia. Most of these species were resident breeders at the study site although two appeared to be local migrants. Six species of hermit hummingbirds (subfamily Phaethornithinae) occurred at Matamatá; although very similar in general morphology and behaviour, they showed different preferences for habitat, food plants and foraging technique. Hermits were predominant in the forest, but in areas of secondary vegetation and along riverine borders, “typical” hummingbirds (subfamily Trochilinae) were more common. The study site consisted of terra firme and várzea forest and an area of riverine secondary vegetation and contained around 60 species of flowering plants visited by hummingbirds. In contrast with most groups of organisms, hummingbirds and hummingbird‐pollinated plants had similar species diversity in primary forest and secondary habitats. The overall abundance of hummingbirds and flowers was significantly higher in areas of riverine secondary growth. The hummingbird community at Matamatá is remarkably species rich when compared with study sites elsewhere in North and South America. However, random null model comparisons among Amazonian hummingbird communities reveal that they share many characteristics in their structure and show a high degree of species overlap.
SparrowhawkAccipiter nisuspredation and Blue TitParus caeruleusadult annual survival rate
Authors: DHONDT ANDRÉ A. , KEMPENAERS BART , CLOBERT JEAN
Published: April 2008

The adult annual survival rate of breeding Blue TitsParus caeruleusdecreased from 0.485 to 0.376 after a pair of SparrowhawksAccipiter nisusstarted to breed in the study plot in 1990, whereas in two neighbouring plots, survival rates did not change. This decrease was likely caused by the Sparrowhawk predation mainly in spring. Although the size of the Blue Tit breeding population did not decrease, there remained fewer nonbreeding floaters, and as a result, replacement polygyny became more common.
Strategies, punctuality of arrival and ranges of migrants in the Kalahari basin, Botswana
Authors: HERREMANS M.
Published: April 2008

The timing and intensity of the first summer rains in the Kalahari basin are highly variable between years. Avian migrants to the area follow two principal strategies. Species arriving before November typically do so before significant rain can be expected and do not use ecological conditions as a proximal cue to time arrival; their arrival was unaffected by the failure of the early rains in 1994. Species arriving after mid‐November respond to the timing and extent of the early rains and were progressively more delayed in parallel to a cumulative deficit in rainfall during the early part of the 1994 wet season. The second strategy results in erratic occupation of parts of the nonbreeding range, so that during drought years, rain‐dependent, late‐arriving species may remain absent from the Kalahari basin, complicating the assessment of the “effective” size of their nonbreeding range.
Temporal partitioning of a floral resource by territorial hummingbirds
Authors: COTTON PETER A.
Published: April 2008

Most studies of territoriality in hummingbirds have focused on intraspecific competition for resources and the consequences for the spatial distribution of individuals within a habitat. As a result, we know little of the effects of interspecific competition for resources and less still of temporal resource partitioning. Here I describe the interactions of four species of tropical hummingbird which defended the same territory at different stages in the flowering period and at different times of the day. The pattern of territory defence was greatly influenced by the dominance hierarchy between species and the costs and benefits of territory ownership. I used a simple economic model to calculate the predicted territory size based on four potential strategies. Hummingbirds appeared to be defending territories of the smallest economical size, agreeing with two hypotheses: (1) that hummingbirds minimize the cost of territory ownership and (2) that hummingbirds maximize the time spent sitting. The model predicted accurately the observed pattern of territory acquisition; hummingbirds initiated defence as soon as the territory contained sufficient resources and were either displaced by a larger species or replaced by a smaller one as the value of the territory changed.
Re‐examination of the capital and income dichotomy in breeding birds
Authors: MEIJER THEO , DRENT RUDI
Published: April 2008

During egg‐formation, energy and protein are deposited in the developing eggs but are, at the same time, needed by the laying female herself. This has been largely overlooked in the discussion on income and capital breeders (Drent & Daan 1980, Thomas 1988). We discuss data on exogenous versus endogenous energy and nutrients used during egg‐formation for 12 well‐studied species ranging from the Adelie PenguinPygoscelis adelie(3400 g) to the Blue TitParus caeruleus(11 g) and calculate which part of thetotalenergy and nutrient requirements (of clutch and laying female) originates from direct food intake and/or from body reserves. Because energy and nutrients are also needed by the laying female, some large species breeding in cold regions deposit sufficient reserve that they can fast completely during egg‐formation (like the Adelie Penguin) and even throughout incubation (like the EiderSomateria mollissima). However, almost all smaller species must forage for most of their energy and nutrients during the egg‐formation period. For the large species, energy and protein of the clutch represent 30% and 70%, respectively, of the total requirements of laying females, much more than in small species like passerines (4% and 40%). Therefore, the requirements for the clutch are much greater in larger than in smaller species, and egg‐production is much more limited by protein than by energy. The effects of food supplementation on timing of laying (moderate advance), on number of eggs laid (not more, when corrected for date) and on egg size (not larger) of income and capital breeders/layers are discussed. It seems that neither the start of egg‐laying nor the number or quality of eggs are directly related to the energetics of the laying female.
Eye structure and foraging in King Penguins Aptenodytes patagonicus
Authors: MARTIN GRAHAM R.
Published: April 2008

Anterior eye structure and retinal visual fields were determined in King Penguins Aptenodytes patagonicus using keratometry and an ophthalmoscopic reflex technique. The cornea is relatively flat (radius 32.9 mm) and hence of low refractive power (10.2 dioptres in air) and this may be correlated with the amphibious nature of penguin vision. The large size of the eye and of the fully dilated pupil may be correlated with activity at low light levels. In air, the binocular field is long (vertical extent 180d̀) and narrow (maximum width 29d̀), with the bill placed approximately centrally—a topography found in a range of bird species which employ visual guidance of bill position when foraging. Upon immersion in water, the optical power of the cornea is abolished, with the effect that the monocular fields decrease and binocularity is lost. King Penguins have a pupil type which has not hitherto been recorded in birds. In daylight it contracts to a square‐shaped pinhole but dilates to a large circular aperture in darkness. This change alters retinal illumination by 300‐fold (2.5 log10 units). When diving, this permits the retina to be pre‐adapted to the low ambient light levels that the birds encounter upon reaching mesopelagic depths. These penguins also forage at depths where ambient light levels, even during the day, can fall below the equivalent of terrestrial starlight. Under these conditions, the birds must rely upon the detection of light from the photophores of their prey. In this they are aided by their absolutely large pupil size and broad cyclopean visual field.
Brood desertion and polygamous breeding in the Kentish Plover Charadrius alexandrinus
Authors: Amat Juan A. , Fraga Rosendo M. , Arroyo Gonzalo M.
Published: April 2008

In the Kentish Plover Charadrius alexandrinus one of the adults, typically the female, deserts the brood when the chicks are a few days old. Once parental care is terminated, adults may initiate a second nesting attempt if sufficient time remains within the season. For these nests, individuals pair with different mates from those of the first nesting attempt, thus becoming sequentially polygamous. In a small population of Kentish Plovers in Fuente de Piedra lake (southern Spain), the duration of biparental care of broods was longer than in other localities. It also showed considerable variation between years that was evidently related to Gull‐billed Tern Gelochelidon nilotica predation pressure on the chicks. There was year‐to‐year variation in the number of polygamous matings. Both the duration of the breeding season and nesting success in the first half of the season limited the occurrence of polygamy. Despite females deserting broods earlier than males, the interval between the first and second nesting of polyandrous females and polygynous males was similar. The interval was not affected by the body condition of females after the first nesting attempt, nor by problems related to egg formation ability, but was probably due to the availability of potential mates. More females than males initiated second nests, suggesting that polygamous opportunities were more limited for males than for females. In terms of delayed breeding, reduced survivorship or reduced breeding opportunities in years following polygamous breeding, polygamous individuals did not have greater costs than non‐polygamous ones. Females with second nests did not seem to be selective in mate choice, mating with any available male. Mates for second nests may therefore be of lower quality than those for first nests, as judged by male plumage characteristics. Clutch sizes and egg characteristics of polyandrous females were similar in first and second nests. Nest success of second nests was only 40% of that of first ones, with nest desertion accounting for 60% of the losses. As the costs of polygamy are apparently low and as breeding success is very variable among years, polygamous breeding of the long‐lived Kentish Plover may be an important breeding strategy with which to increase individual lifetime reproductive success.