bluuebunny/crossref_metadata_2025 huggingface dataset:
A distinctive new species of vireo (Passeriformes: Vireonidae) from the Western Andes of Colombia
Authors: Salaman Paul G. W. , Stiles F. Gary
Published: April 2008

On the basis of field observations and two specimens from two localities in the Chocó biogeographic region of western Colombia, we here describe Vireo masteri, sp. nov. This species appears to be most closely related to Vireo carmioli of Costa Rica and west Panama but is much smaller and has a distinctive long superciliary stripe, a feature otherwise unknown in the subgenus Vireo, of which it is the southernmost known taxon. Vireo masteri appears to be restricted to a narrow belt of premontane pluvial forests from 1200 to 1600 m on the Pacific slope of the Western Andes. We present notes on the behaviour, ecology and conservation of this new species.

Con base en observaciones en el campo y dos especímenes de dos localidades en la región biogeográfica del Chocó colombiano, describimos una nueva y distintiva especie de vireo o chiví, Vireo masteri, sp. nov. Esta especie parece mas afin a Vireo carmiloi de Costa Rica y Panamá que a cualquier otra especie, pero es de menor tamaño y tiene una lista superciliar larga y llamativa, caracteristica única en la subgénero Vireo, del cual es la forma más sureña. Vireo masteri aparentemente se restringe a una faja altitudinal angosta (1200–1600 msnm) de bosque pluvial premontano en la vertiente del Pacífico de la Cordillera Occental de los Andes colombianos. Presentamos anotaciones sobre la ecología, el comportamiento, y la conservación de esta neueva especie.
Correlation between egg size and clutch size in the Pied Flycatcher Ficedula hypoleuca in cold and warm summers
Authors: Järvinen Antero
Published: April 2008

The correlation between egg size and clutch size was studied in the Pied Flycatcher Ficedula hypoleuca in Finnish Lapland from 1975 to 1994. The hypothesis tested was that the tradeoff phenomenon is masked by warm weather. When data for 20 years were pooled, there was no correlation. However, when years were analysed separately, a negative correlation was observed for five of the years. Over 12 years, the correlation coefficient between egg size and clutch size was not significant, and for 3 years it was significantly positive. The size and magnitude of the correlation were related to temperature during the pre‐laying and egg‐laying periods. Of the annual variation, 34% was explained by the mean temperature in early summer. It is suggested that trade‐off between egg size and clutch size may not be apparent in central (southern) parts of the distribution area of the species where climate is warmer. In the future, global warming may alter reproductive strategies of birds. Long‐term data may thus be useful in the analysis of such effects and in testing of theoretical questions in ecology.
Brood size manipulations within the natural range did not reveal intragenerational cost of reproduction in the Willow TitParus montanus
Authors: Orell Markku , Rytkönen Seppo , Koivula Kari , Ronkainen Minna , Rahiala Markku
Published: April 2008

To test for the existence of a reproductive cost, we manipulated brood sizes (‐2 and +2 nestlings) over 6 years in a northern population of Willow TitsParus montanusbreeding in natural holes. Possible effects were sought in subsequent survival and fecundity of the parents. Parents given extra chicks made more feeding visits than did parents with reduced and control broods. However, this was not reflected in differences in parental body‐weight between groups at the end of the nestling period. Brood size manipulation did not significantly affect female or male survival. In 4 out of 6 years, there was a weak and nonsignificant effect on male survival, consistent with a cost of reproduction. Female and male fecundity in the year following the experiment was not affected by the manipulations. Thus, the data do not give evidence of an intragenerational cost of reproduction in the Willow Tit. Parents appeared unwilling to increase their breeding effort to a level which jeopardized their own survival or future breeding success. It is possible that, because of the time constraints in northern latitudes, females work under their capacity and lay smaller clutches than would otherwise be most profitable. Thus, no costs to the parents would be expected as a consequence of manipulations. These results suggest that the current reproductive rate is not maintained by reproductive cost in the Willow Tit. However, the results do not rule out the possibility that selection has operated outside the current range of reproductive rates during evolutionary history of the species.
Phylogeny and species limits in the Palaearctic chiffchaff Phylloscopus collybita complex: mitochondrial genetic differentiation and bioacoustic evidence*
Authors: Helbig A. J. , Martens J. , Seibold I. , Henning F. , Schottler B. , Wink M.
Published: April 2008

Nucleotide sequences of the mitochondrial cytochrome b gene (1041 bp), analysis of vocalizations and behavioural evidence from zones of contact were used to reassess the species limits and phylogenetic relationships at the species and subspecies levels in the Phylloscopus collybita complex. A new classification is proposed which recognizes four biological species. Phylloscopus brehmii (Iberia) and P. canariensis (Canary Islands) are genetically and bioacoustically highly distinct. There is no mitochondrial gene flow between them or with P. collybita. The Mountain Chiffchaff P. sindianus (with subspecies sindianus and Iorenzii) is equally distinct genetically from southwest Asian subspecies of P. collybita (caucasicus, brevirostris). The status of the Siberian form tristis, which shares potentially synapomorphic characters with the Mountain Chiffchaff (ascending song notes, grey‐brown adult plumage) but genetically closely resembles P. c. collybita and P. c. abietinus, remains uncertain. In two zones of secondary contact between taxa with “greenish” (P. collybita) and brownish plumage, hybridization is either unrecorded (caucasicus v lorenzii, Caucasus Mountains) or its extent is insufficiently known (abietinus v tristis, west of Ural Mountains). A phylogeny reconstructed from nucleotide sequences agrees with one based on song and some morphological characters in identifying P. brehmii as the oldest branch within the chiffchaff group. Of the remaining taxa, four fall into a clade with greenish plumage (P. collybita ssp.), two into one with brownish plumage (P. s. sindianus, P. s. lorenzii), while the position of P. canariensis with respect to these two clades is uncertain. Molecular and phenotypic phylogenies contradict each other regarding the affinities of P. (ssp.?) tristis.
The use of thermals by soaring migrants
Authors: Leshem Yossi , Yom‐Tov Yoram
Published: April 2008

The use of thermals during the spring and autumn migration across Israel by four species of soaring birds (White Pelican Pelecanus onocrotalus, White Stork Ciconia ciconia, Lesser Spotted Eagle Aquila pomarina and Honey Buzzard Pernis apivorus) was studied by monitoring them with a motorized glider, light aircraft and radar. This is the first study in which soaring migrants have been followed in flight for any length of time and their flight performance has been recorded directly. The birds flew in an average height band between 344 and 1123 m above ground level. Altitude increased from the morning towards noon and decreased again in the afternoon. Average velocities were 29.2 km/h, 38.7 km/h, 50.9 km/h and 45.2 km/h for White Pelicans, White Storks, Lesser Spotted Eagles and Honey Buzzards, respectively. Atmospheric conditions had a major effect on flight velocity. White Storks showed a positive correlation between the flight velocity and the height between the base and top of the thermals. In White Pelicans, there was a correlation between velocity and mean height. Wing load (body mass/wing area) was positively related to the climbing time in thermals and negatively related to the mean height used by a species. There was also a positive, but not significant, relationship between wing load and velocity. Soaring birds appreciably extend the distance covered in migration in relation to the straight line from their breeding to wintering grounds (by 48–91%). The increased distance, caused through circumventing sea areas, ranged between 22–34%, while the increase resulting from soaring accounted for an additional 22–57% of the route.
Effects of variation in egg size and hatching date on survival of Lesser Scaup Aythya affinis ducklings
Authors: Dawson Russell D. , Clark Robert G.
Published: April 2008

The consequences of avian egg‐size variation on offspring quality and survival remain unclear. We evaluated the effects of egg‐size and hatch‐date variation on survival of Lesser Scaup Aythya affinis ducklings in the wild. Duckling mass at hatching increased significantly with increasing egg size. Ducklings from larger eggs survived better than those from smaller eggs. We suspect that ducklings from larger eggs survived better because of advantages associated with larger or more efficient utilization of nutrient reserves, or both. We were unable to detect any within‐clutch differences in egg size of survivors and non‐survivors, nor any consistent direction in the difference in egg size between survivors and nonsurvivors within clutches. This suggests that within‐clutch variation may be insufficient to have survival consequences for offspring. In addition, ducklings that hatched later in the breeding season had a higher probability of survival. We suggest a food‐dependent hypothesis as an explanation for the seasonally increasing survival and for later nest initiation of Lesser Scaup compared with other North American ducks.
Effects of experimental food provisioning on reproduction in the Jackdaw Corvus monedula, a semi‐colonial species
Authors: SOLER MANUEL , SOLER JUAN JOSE
Published: April 2008

Two Jackdaw Corvus monedula colonies were given supplementary food before and during breeding in 1983. Breeding density and cavity use were compared with those of the same colonies in previous years, when no food was provided. Predation rate and reproductive parameters were compared with those in the same colonies in previous years and with those of two control colonies, without experimental food. Jackdaws preferred safe cavities with small minimum nest‐entrance dimensions and avoided those with a high risk of nest predation. In experimental (fed) colonies, however, there was a tendency to use all cavities, which resulted in an increased breeding density. No nests were preyed upon by Ravens Corvus corax in the experimental colonies because supplemental food favoured group defence by increasing colony size and by increasing the time the Jackdaws spent in the colony. Additional food advanced laying date, increased clutch size independently of laying date and increased fledging success. Supplementary food significantly increased fledging success in less than half of all experimental studies on birds. We suggest that the key to this problem is the species' breeding strategy, and we show that supplementary food significantly increased fledging success in brood‐reduction strategist species but not in species which directly adjusted their clutch size.
Diving patterns in shags and cormorants (Phalacrocorax): tests of an optimal breathing model
Authors: LEA STEPHEN E. G. , DALEY CLAIRE , BODDINGTON PETER J. C. , MORISON VICTORIA
Published: April 2008

Four species of shags and cormorants were observed while diving for food in estuaries and coastal waters in southwest England and the South Island of New Zealand. Times spent on the surface and under water were recorded. The correlations between dive and surface times were examined between and within bouts of dives. All species showed a positive correlation between the mean dive time and the mean surface time for the bout. Analysis of within‐bout correlations, however, showed different patterns between species. For the Shag Phalacrocorax aristotelis, there was a positive relationship within bouts between dive time and the preceding surface time, and correlations between dive time and the succeeding surface time were due only to the autocorrelation of surface times. This anticipatory breathing pattern was predicted by an optimal breathing model proposed by D. L. Kramer. For the Little Shag Phalacrocorax melanoleucus, dive times were significantly correlated within bouts with the following surface time, but correlations with the succeeding surface time were due only to the autocorrelation of surface times. This implies that breathing in this species is reactive rather than anticipatory. The Cormorant Phalacrocorax carbo and the Pied Shag Phalacrocorax varius showed independent within‐bout correlations with both preceding and succeeding surface times, implying both anticipatory and reactive breathing. The within‐bout dependence of dive time on surface times was weak in all species, suggesting that oxygen is stored from one dive to another to some extent.
Site use and fidelity in the Common Guillemot Uria aalge
Authors: HARRIS M. P. , WANLESS S. , BARTON T. R.
Published: April 2008

The site fidelity of 470 colour‐ringed Common Guillemots Uria aalge with at least 1 year of breeding experience was followed on the Isle of May from 1982 to 1993. On average, 85.7% of birds recorded breeding at a site in any year were present at the same site in the following season. Of those which did not retain their site, 35% had moved to another site, 25% were nonbreeders and 40% were not seen. Site‐ fidelity of birds which returned to the colony the next year was 91%. There were no significant age or sex effects, but there were significant (and unexplained) year and area effects. Most birds which changed sites moved less than 2 m. Some birds which obtained a new site improved their nesting success, but many others became nonbreeders; it is speculated that the former chose to move site, whilst the latter had been evicted.
The influence of food availability on the breeding effort and reproductive success of Arctic Skuas Stercorarius parasiticus
Authors: PHILLIPS R. A. , CALDOW R. W. G. , FURNESS R. W.
Published: April 2008

Territorial attendance, chick growth rate and breeding success of Arctic Skuas Stercorarius parasiticus in Shetland were lowest in the late 1980s when recruitment of Sandeels Am‐modytes marinus in the surrounding waters was poor. The relationships between both fisheries‐based and avian indices of food availability and annual variation in Arctic Skua chick growth and breeding success between 1976 and 1994 were better described by a threshold effect rather than linear functions. Arctic Skuas conform to the model proposed by Cairns, which predicts the responses of seabirds to changes in prey availability. Skua clutch size, egg volume, hatching success and hatching date were not reliable indices of Sandeel availability. However, annual fluctuations in Arctic Skua breeding numbers may be a useful indicator of changes in prey abundance.
Effect of observer differences on abundance estimates of seabirds from ship‐based strip transect surveys
Authors: MEER J. VAN DER , CAMPHUYSEN C. J.
Published: April 2008

Data from four ship‐based strip transect surveys of seabirds, in which six observer teams from several countries cooperated, were used to estimate observer differences. The numbers of birds per sampled area as reported by the various observer teams were used to estimate differences among observer teams. As overlap in effort was not complete (all teams did not work in exactly the same areas at the same times), a log‐linear model was used to correct for differences due to survey and region effects and the state of the sea. Considerable observer differences were found. For example, three teams out of five observed less than 16% of GuillemotUria aalgeand even less than 10% of KittiwakeRissa tridactylarelative to the team that reported the highest densities.
Demography of Bristle‐thighed Curlews Numenius tahitiensis wintering on Laysan Island
Authors: MARKS JEFFREY S. , REDMOND ROLAND L.
Published: April 2008

We studied the nonbreeding ecology of Bristle‐thighed Curlews Numenius tahitiensis from 1988 to 1991 on Laysan Island in the Northwestern Hawaiian Islands. Using capture‐recapture analysis, we estimated that 300–350 curlews wintered on the island. Annual survival was >85% for adults and 92% for first‐year birds. Young birds remained on the island until at least their third calendar year, when some individuals made “exploratory” visits to other islands in the Northwestern chain. Most of the birds marked in their first year migrated north to the breeding grounds when they were 3 years old; several birds remained on the island until they were at least 4 years old. Adults returned to the same discrete home ranges year after year, whereas subadults (which do not migrate) tended to use a greater portion of the island. At least 60% of the subadults marked from 1988 to 1990 returned to the island to winter as adults. Because young curlews arrived after adults and experienced high survivorship while on the island, there did not appear to be intense competition for space at Laysan even though the island is at the northern end of the species' winter range.
Sugar preferences of some southern African nectarivorous birds
Authors: DOWNS C. T. , PERRIN M. R.
Published: April 2008

Three southern African nectarivorous passerine birds, Gurney's Sugarbird Promerops gur‐neyi, the Malachite Sunbird Nectarinia famosa and the Black Sunbird Nectarinia amethystina, were tested to determine their hexose and sucrose preferences. All three species preferred sucrose when offered a choice of 0.25 M solutions of glucose, fructose and sucrose. However, when the concentrations were increased to 0.73 M, the three species showed no preference for any of the three sugars. The choice made at low concentrations (equivalent to the lower limit of the range of nectar concentrations of preferred nectar‐producing plants) may reflect preference for the sugar with the highest energy reward. We also examined the proposition that birds offered a choice of different concentrations of one sugar would show ranked preferences and maximize their rate of energy return by selectivity. In contrast to expectations, Gurney's Sugarbird and the Malachite Sunbird showed no preference for the highest concentrations. We suggest that dietary choices in these species indicate the birds had either reached a limit where they had sufficient energy intake or were affected by post‐ingestion constraints.
Breeding of the Seychelles Magpie Robin Copsychus sechellarum and implications for its conservation
Authors: KOMDEUR JAN
Published: April 2008

The total population of the Seychelles Magpie Robin Copsychus sechellarum declined from 38–41 birds in 12–13 territories in 1977–1978 to 17–21 birds in eight to nine territories in 1988–1990 and was entirely confined to Fregate Island (210 ha) in the Seychelles. After a successful cat eradication program in 1981–1982, recruitment improved, although the abandonment of agriculture had caused a reduction in the amount of feeding habitat and hence in the carrying capacity of the island. The population declined because of the failure of recruitment to compensate for the annual adult mortality. Foraging activity of the Magpie Robin was greater in high‐quality territories (measured by soil invertebrates available), leading to increased reproductive success. Through supplementary feeding, five times as many recruits were produced. Of the 11.5 potential annual breeding recruits, 5.3 are required to compensate for adult mortality, and the other 6.2 recruits can be regarded as “surplus” contributing to an increase. Magpie Robins prefer to breed in rotten trees, which are a scarce resource. The greater the distance between the nest site and feeding areas, the less time was spent in incubation and nest guarding, resulting in greater egg loss. Because of lack of suitable areas for establishing territories, many young Magpie Robins became “floaters”. Nest disturbance, both by these floaters and by the introduced Indian Mynah Acridotheres tristis, had adverse effects on the breeding success of robins. A recovery plan has been designed to save the Magpie Robin. Territories have been improved for feeding (by tree planting) and for breeding (by providing nestboxes and reducing nest disturbances). Given the vulnerability of one small island, the presence of surplus birds (supported mainly by supplementary food) and the suitability of neighbouring Aride Island (68 ha), successful translocations to this island took place in 1992 and 1994. Given the presence now of 47 individuals on two islands, it is hoped that the species will pull back from the brink of extinction.
Intraclutch egg‐size variation in the Barnacle Goose Branta leucopsis: an egg‐removal experiment
Authors: WILLIAMS T. D. , JEFFS C. , MURRAY K. A. , CHOUDHURY S.
Published: April 2008

We carried out an egg‐removal experiment on Barnacle Geese Branta leucopsis to test the hypothesis that tactile contact between the brood patch and eggs accumulating in the nest during laying was causally related to intraclutch egg‐size variation, acting through the development of incubation behaviour. Egg removal had no effect on mean egg mass, relaying interval or clutch size: mean (±s.e.) clutch sizes for first clutches were 4.9 ± 0.9 and 4.7 ± 0.9 eggs for control and experimental females, respectively. We therefore conclude that Barnacle Geese have a determinate pattern of egg laying. Daily removal of all eggs from the first‐laid egg did not affect the within‐clutch pattern of egg‐size variation: in both control and experimental clutches the first egg was relatively small, the second or third egg was largest and there was a linear decline in egg size to the smallest, last‐laid egg. There was no significant difference in either the absolute or relative size of the last‐laid eggs in control and experimental clutches. Tactile contact with eggs in the nest, therefore, is not required for the expression of intraclutch egg‐size variation in Barnacle Geese. In this respect, determinate‐laying Barnacle Geese differ from species with indeterminate laying patterns (e.g. gulls) where egg removal does affect the normal pattern of within‐clutch egg‐size variation. If hormonal changes (e.g. prolactin) associated with onset of incubation are causally related to the intraclutch decrease in egg size, then the stimuli involved appear to differ between determinate and indeterminate layers.
The mating system of the White‐throated Magpie‐jay Calocitta formosa and Greenwood's hypothesis for sex‐biased dispersal
Authors: LANGEN TOM A.
Published: April 2008

Greenwood explained the different sex bias in dispersal of birds (usually female biased) and mammals (usually male biased) by a difference in mating systems: male birds primarily defend resources while male mammals primarily defend females. The White‐throated Magpie‐jay Calocitta formosa is unusual among birds in that females are philopatric and jointly defend permanent resource territories while males disperse before they are 2 years of age. One female in a group is the primary breeder. One male joins the group permanently as her mate. Males that do not have a permanent breeding position circulate among groups and attempt to mate with both the primary breeding female and other group females. Other females feed the primary breeder and her offspring and also pursue other reproductive behaviour, including secondary nesting in the territory and egg dumping into the primary breeder's nest. I argue that the unusual dispersal pattern in this species is a result of the alternative reproductive strategies that can be pursued by males and females excluded from being primary breeders. The White‐throated Magpie‐jay conforms to Greenwood's predictions: males pursue a mate defence rather than resource defence mating system and they are the dispersing sex. The primary factor influencing alternative reproductive tactics may be asynchronous reproduction among groups during the long breeding season arising from frequent renesting in an area of high nest predation.
Fat reserves of migrating passerines at arrival on the breeding grounds in Swedish Lapland
Authors: SANDBERG ROLAND
Published: April 2008

Mist‐net capture data taken during 6 years (1988–1990 and 1992–1994) of field work were used to describe the arrival sequences and fat loads of nine species of migratory passerines which breed in a near‐Arctic environment in Swedish Lapland. Long‐distance migrants arrived with significantly larger mean fat reserves than did medium‐ and short‐distance migrants. Long‐distance migrants carried fat loads at arrival which corresponded to potential remaining flight distances between 242 and 500 km. When females and males arrived on the breeding grounds simultaneously, females carried significantly larger energy reserves than did males in seven out of nine species. In contrast, when the sexes showed a significant difference in median arrival date (two out of nine species), there was no difference in mean fat load carried into the breeding area. A relationship was found between the migratory habits and foraging ecology of each species and the amount of fat reserves at arrival, suggesting that species‐specific migratory distances and feeding habits determine the amount of fat that is needed during the transition period between migration and onset of breeding. The short growing season in the study area restricts the time available for breeding and moult, and large energy reserves at arrival may speed up the breeding schedule to counteract possible time constraints. Overloading at the last stopover site during spring migration may be an adaptation allowing birds to cope with a restricted time frame for breeding and moult at high latitudes.
Social dominance in free‐living Willow Tits Parus montanus: determinants and some implications of hierarchy
Authors: LAHTI KIMMO , KOIVULA KARI , ORELL MARKKU , RYTKÖNEN SEPPO
Published: April 2008

Several features of social dominance among Willow Tit Parus montanus winter flocks were examined during a four‐winter study. Birds of both sexes were evenly distributed over the 33 flocks studied. In nearly half of the flocks there was an adult pair accompanied by yearlings, but one‐third of the flocks consisted of more than two adults with yearlings. Males were found to be dominant over and larger than females. Within a sex, yearlings were usually subordinate to adults. The effect of size on dominance, after controlled for sex and age, remained obscure in our field data. The hierarchical status of an individual was found to rise or at least stay the same in different years, which supports the “hopeful dominants” hypothesis, i.e. birds stay in flocks hoping to achieve a higher status in the future. The ranks of mates correlated highly significantly, implying that high‐ranking birds were paired with other high‐ranking birds and low‐ranking birds with other low‐ranking birds. Birds of different age and sex did not show any differences in the proportion of initiated aggressive encounters directed at other individuals. However, males were more aggressive to other males than to females and also tended to behave less aggressively towards their own mates than towards other individuals in the flock. This could be a male strategy to strengthen the pair‐bond and to enhance mate protection described earlier in
Effects of population growth on Crested Tit Parus cristatus post‐fledging settlement
Authors: LENS LUC , WAUTERS LUC A.
Published: April 2008

From 1987 to 1993, the winter density of Crested Tits Parus cristatus in north Belgium increased 2.76 times. The increase was the result of high annual survival rates of both adult and first‐year birds despite a low reproductive success (number of fledglings per female) due to high predation of nestlings. A fc‐factor analysis assuming intermediate costs of post‐fledging dispersal and settlement gave the best fit. First‐year birds had two options when trying to settle in a prospective breeding territory: (1) establish a new territory during August or early September and defend it against neighbouring flocks during winter or immigrants in early spring or both, or (2) overwinter as a subordinate in a mixed‐age flock and pair with a widowed adult or replace a territory owner in early spring (“hopeful dominant stategy”). Settlement strategies varied with density; at low density, only the hopeful dominant strategy was observed, whereas at higher density, both strategies occurred.
Dawn chorus and female behaviour in the Willow Tit Parus montanus
Authors: WELLING PETTERI , KOIVULA KARI , ORELL MARKKU
Published: April 2008

We studied the effect of female behaviour on the dawn chorus of Willow Tits Parus montanus. Ten females were temporarily kept in their nest holes in order to delay their dawn emergence. Simultaneously, their mates' singing behaviour was measured. We compared the control dawn behaviour (during which the females emerged when they wanted) with that during the experimental delay. The dawn song by the males lasted longer when the females' emergences were delayed. Our results show that the duration of the dawn chorus is directly related to the female's behaviour. We suggest that at least one function of the dawn song is intrapair signalling, which is often linked to sperm competition.
A comparison of the feeding ecology of wintering Hen Harriers Circus cyaneus centred on two heathland areas in England
Authors: CLARKE ROGER , COMBRIDGE MICHAEL , COMBRIDGE PETER
Published: April 2008

Small passerines were the principal prey in pellets from Hen Harrier Circus cyaneus communal winter roosts in Breckland and the New Forest. Skylark Alauda arvensis remains predominate in the pellets from Breckland. Dunnock Prunella modularis and Greenfinch Carduelis chloris were also important. The contents of New Forest pellets reflected the position of each roost. In pellets from a roost on the northern edge of New Forest heathland and close to farmland, Skylark was by far the predominant prey. Wren Troglodytes troglodytes and Linnet Carduelis cannabina were the next most important passerines. Pellets from the more extensive heather heathland in the south of the New Forest showed greater dependence on the heathland community of insectivorous passerines, with Wren, Dartford Warbler Sylvia undata and Meadow Pipit Anthus pratensis occurring as prey in that order of frequency. Pellets from a roost in northwest New Forest heathland with less heather and closer to farmland contained mainly a mixture of farmland‐and heathland‐feeding passerines. The directions of arrival and departure at roosts indicated that the Breckland‐roosting harriers hunted mainly in arable fenland and the New Forest edge‐roosting harriers in arable downland. Counts of the principal passerine prey species in roost catchment areas indicated that Greenfinch and Linnet were most abundant in arable fenland and arable downland squares, respectively, and the Wren was most abundant in the New Forest catchment area as a whole. The influence of the distribution of weed species on the species of seed‐eating passerines in prey was investigated. Proportions of passerines in pellets from the Breckland and New Forest edge roosts were positively correlated with the proportions of “grey” males. Proportions of finches in both the Breckland and the New Forest edge‐roost pellets declined sharply after January. There was a shift toward lagomorphs in the diet after January and a suggestion that this was positively correlated with the proportions of ringtails at the Breckland roost. Factors affecting prey composition and selection of foraging habitat, the effect of harrier predation on Dartford Warbler numbers and the implications for differential distribution of the harrier sexes in winter are discussed.
The Storm's Stork Ciconia stormi in Indonesia: breeding biology, population and conservation
Authors: DANIELSEN FINN , KADARISMAN RIZA , SKOV HENRIK , SUWARMAN UNANG , VERHEUGT WIM J. M.
Published: April 2008

Storm's Stork Ciconia stormi is one of the rarest of the storks, regarded as globally endangered and found only in parts of western Indonesia, Malaysia and Brunei. Prior to this study, its breeding biology was unknown and the population status in Indonesia was not well understood. Its breeding habitat, prey, behaviour, voice, eggs and the development of the young are described here for the first time. Breeding biology was studied in 1989 at a nest in south Sumatra, Indonesia. The nest was in the transition zone between mangrove and freshwater swamp forest. Incubation took less than 29 days, and two eggs hatched. Fish 2–7 cm long comprised 67% of the prey for feeding young. The chick was fully feathered at 52–57 days and was seen flying when 57–62 days old. The species is rare in south Sumatra. It occurs in low numbers and flocks of up to seven birds were observed. The density is estimated at 20–40 birds within 110,000 ha of primary swamp forest. At this density, the population would be below 100 birds in south Sumatra and between 100 and 300 in Indonesia. The species is threatened by development and conversion of primary swamp forest.
Breeding success and chronology of Wood Storks Mycteria americana in northern and central Florida, U.S.A.
Authors: RODGERS JAMES A. , SCHWIKERT STEPHEN T.
Published: April 2008

The breeding success and chronology of Wood Storks Mycteria americana were studied at eight colonies in northern and central Florida during 1981–1985. Mean ± s.d. clutch size for all colony‐years was 3.07 ± 0.56 (n = 2694 nests), with three‐egg clutches (72%) most frequent. Mean clutch size among all colonies and years ranged from 2.73 ± 0.55 to 3.41 ± 0.61. Many colonies exhibited significant negative trends in clutch size with, hatching date because of a proportional decrease in four‐egg clutches later in the season. Mean colony clutch size was not correlated with nest numbers, nesting density or mean hatching date within most years. Mean ± s.d. number of fledglings for all colonies and years was 1.29 ± 1.16 fledglings per nest (n = 2812 nests). Mean annual fledging rates in colonies ranged from 0 (colony failed) to 2.66 fledglings per nest. Most breeding failure occurred prior to egg hatching, and the second highest mortality occurred between hatching and 2 weeks of age. Four‐egg clutches fledged more storks than three‐egg clutches, which in turn were more successful than two‐egg clutches. However, all clutch sizes showed similar fledgling per egg rates. The seasonal decline in productivity was associated proportionally with smaller clutch sizes later in the breeding season. An increase in mean hatching date was correlated with an increase in latitude. There was greater within‐year breeding synchrony among colonies than interyear breeding synchrony within each colony. Breeding synchrony was not correlated with mean hatching date, latitude, longitude, nest numbers or nesting density.
Behavioural ecology of the North Sulawesi Tarictic Hornbill Penelopides exarhatus exarhatus during the breeding season
Authors: O'BRIEN TIMOTHY G.
Published: April 2008

Two nests of the North Sulawesi Tarictic Hornbill Penelopides exarhatus exarhatus were monitored for one breeding season (April‐July). The females sealed themselves into the nest cavities and remained there for 70–90 days. Incubation was estimated at 16–19 days, and at both nests two offspring fledged. Tarictic Hornbills are cooperative breeders with up to three helpers at the nest and defend foraging territories of 72–139 ha. Food items delivered to the nest included fruits of 34 species (85% of diet items) and invertebrates. Provisioning by helpers allowed breeding males to reduce investment in parental care and may accelerate the development rates in chicks. Constraints on dispersal probably result from habitat saturation rather than living in an unpredictable environment.
Geographic variation in the occurrence of song types in Nuthatch Sitta europaea populations
Authors: MATTHYSEN E.
Published: April 2008

The frequency of occurrence of song types of Nuthatches Sitta europaea was examined in nine study areas in northern Belgium. Birds from different areas did not differ consistently in the use of five distinct song types, and similarity in the occurrence of song types was not related to geographic distance, except that one song type, “Ud”, was almost wholly absent from four areas in the northeast of the investigated area. In the remaining areas, the frequency of occurrence of this song type varied from 10% to 20%. This presence/absence pattern appears to be stable between years. I suggest that the birds from the four areas lacking “Ud” were descended from a formerly small and highly isolated population near Antwerp, where the song may have been lost through a founder effect. Birds in areas with and without “Ud” did not differ in their response level to playback of this song, except that those in areas without “Ud” were incapable of song matching.
The effect of ectoparasite nest load on the breeding biology of the Penduline Tit Remiz pendulinus
Authors: DAROLOVà A. , HOI H. , SCHLEICHER B.
Published: April 2008

In this study we investigated the importance of ectoparasite load in the nest on the breed‐ing system of the Penduline TitRemiz pendulinus,examining the effect of mite abundance in the nest on mate choice, reproductive success and parental effort. The two most common ectoparasites were the Northern Fowl MiteDermanyssus hirundinisand the Northern Feather MiteOrnithonyssus sylviarum.The results show that mite load is important in mate choice but has no adverse effect on reproductive success. The results also indicate that infestation level is related to the quality of the male (mask‐width). Parental feeding rate was negatively related to mite load. This relationship indicated that Penduline Tits did not compensate for higher parasite loads by increasing feeding but rather reflected the con dition of the parent and its investment in self‐maintenance behaviour.
Brent Geese Branta bernicla and Zostera; factors affecting the exploitation of a seasonally declining food resource
Authors: PERCIVAL S. M. , EVANS P. R.
Published: April 2008

Brent Geese Branta bernicla wintering at Lindisfarne, northeastern England, fed almost exclusively on intertidal habitats. Their main food supply was two species of Eelgrass Zostera noltii and Zostera angustifolia. Although abundant when the birds arrived in September, this Zostera was rapidly depleted during the period October‐December. Brent Goose food intake rate declined with the decreasing food supply, and the birds responded by extending the time that they spent feeding. When it was no longer possible to extend the time spent feeding (i.e. they were feeding for all of the time that the food supply was available to them), they moved away from the site. The geese fed extensively at night in order to achieve their daily feeding requirements, especially later in the season. Conversion of daily food intake to energetic intake suggested that there may have been an energetic trigger acting: the geese left the site when they were unable to satisfy their basic energy demand. No evidence was found for direct interference competition between Brent Geese and the other grazer in the system, Wigeon Anas penelope: the two species showed no spatial segregation in their feeding areas at the scale investigated nor any temporal avoidance of each other.
Low reproductive success of the endangered Takahe Porphyrio mantelli on offshore island refuges in New Zealand
Authors: BUNIN J. S. , JAMIESON I. G. , EASON D.
Published: April 2008

Many of New Zealand's endangered birds have been transferred from the “mainland” of the North and South Islands to smaller coastal islands free from introduced predators and competitors. The transfer of Takahe Porphyrio mantelli (Plate 1) to offshore islands is unique because these highly endangered, flightless rails are being moved from alpine‐tussock habitat of Fiordland, the last remaining natural population, to substantially different lowland habitat on island refuges. Despite the fact that 30% of the approximately 160 Takahe left in the wild now live on coastal islands, a detailed analysis on the success of the island populations has never been undertaken. Using data available from New Zealand's Department of Conservation, we found that while adult survivorship of Takahe on islands is high, reproductive success is significantly lower than in Fiordland. Most factors examined, including inbreeding and nutrient deficiency, had no significant effect on reproductive success of Takahe breeding on islands. Island pairs produced fewer eggs and juveniles in the first year of their pair bond relative to all other years. Hence the large number of transfers of birds between islands during the initial stages of the relocation program may have resulted in a higher frequency of pair formation and thus may have contributed to the islands' lower reproductive success. Why first clutches did so poorly (four juveniles from 43 clutches) compared with second (11 from 36) and third (six from 13) clutches is not known but was one of the main contributing factors for island pairs making greater nesting effort but significantly lower returns than birds breeding in Fiordland. In addition, some individual birds have been very successful in producing young relative to other birds, suggesting that important differences in quality of some breeders may also exist. We expect island productivity will improve over time as the number of interisland transfers of Takahe decreases and as the proportion of breeding birds raised in the island environment increases.
Flight speed of seabirds in relation to wind speed and direction
Authors: SPEAR LARRY B. , AINLEY DAVID G.
Published: April 2008

We studied flight speed among all major seabird taxa. Our objectives were to provide further insight into dynamics of seabird flight and to develop allometric equations relating ground speed to wind speed and direction for use in adjusting seabird density estimates (calculated from surveys at sea) for the effect of bird movement. We used triangulation at sea to estimate ground speeds of 1562 individuals of 98 species. Species sorted into 25 “groups” based on similarity in ground speeds and taxonomy. After they were controlled for differences inground speed, the 25 groups sorted into eight major “types” on the basis of response to wind speed and wind direction. Wind speed and direction explained 1664% of the variation in ground speed among seabird types. For analyses on air speed (ground speed minus apparent wind speed), we divided the 25 groups according to four flight styles: gliding, flap‐gliding, glide‐flapping and flapping. Tailwind speed had little effect on air speed of gliders (albatrosses and large gadfly petrels), but species that more often used flapping decreased air speed with increase in tailwinds. All species increased air speeds significantly with increased headwinds. Gliders showed the greatest increase relative to increase in headwind speed and flappers the least. With tailwind flight, air speeds were greatest among species with highest wing loading for each flight style except gliders, which showed no relationship. For headwind flight, species with higher wing loading had higher air speeds; however, the relation was weaker in flappers compared with species using some amount of gliding. In contrast, analyses for air speed ratio (i.e. difference between air speed in acrosswinds [with no apparent wind] and speed flown into headwinds, or with tailwinds, divided by speed acrosswind) revealed that among species using some flapping, and with lower wing loading (surface‐feeding shearwaters, small gadfly petrels, storm petrels, phalaropes, gulls and terns), adjusted air speeds more than those with higher wing loading (alcids, “diving shearwaters”, “Manx‐type shearwaters”, pelicans, boobies and cormorants). As a result, most flappers of low wing loading flew much faster than Vmr (the most energy efficient air speed per distance flown) when flying into headwinds. We suggest that better‐than‐predicted gliding performance with acrosswinds and tailwinds of large gadfly petrels, compared with albatrosses, resulted from a different type of “soaring” not previously described in seabirds.
Intermittent breeding in the Herring GullLarus argentatusand the Lesser Black‐backed GullLarus fuscus
Authors: CALLADINE J. , HARRIS M. P.
Published: April 2008

Thirty‐three percent and 37% of adult Herring GullsLarus argentatusand 34% and 40% of adult Lesser Black‐backed GullsLarus fuscus, all with some previous breeding experience, failed to breed in 1993 and 1994, respectively. About half of these intermittent breeders of both species failed to breed in both years. Common amongst the intermittent breeders were smaller individuals, birds with low survival chances and relatively unsuccessful breeders.
Breeding ecology of the FulmarFulmarus glacialisand the KittiwakeRissa tridactylain high‐arctic northeastern Greenland, 1993
Authors: FALK KNUD , MØLLER SØREN
Published: April 2008

The breeding ecology of the FulmarFulmarus glacialisand the KittiwakeRissa tridactylain the high Arctic was studied in relation to the occurrence of the northeast water polynya in northeasternmost Greenland (80d̀N). Mean laying dates were 31 May in the Fulmar and 18 June in the Kittiwake; the total nesting season for the Fulmar just matched the time window of the polynya opening period. Fulmar colony attendance fluctuated within a period of 11.6 days because of variation in nonbreeding prospectors but showed no clear diurnal variation. Fulmar incubation shifts, on average, lasted 6.1 days (range 1–13 days), which is significantly longer than elsewhere, and the average chick‐guard period of 10.9 days (range 1–17 days) was significantly shorter than in other studies. Egg neglect occurred in 18% of Fulmar nests or 0.7% of nests per day. Overall breeding success (chicks fledged per egg laid) was 0.56 in the Fulmar and 0.67 in the Kittiwake; the latter produced 1.4 young per active nest or 1.2 per completed nest. Mean Kittiwake clutch size was 2.03; larger clutches were laid early. Nest site characteristics (presumably reflecting nest predation risk) and breeding behaviour affected breeding success. in the Fulmar, hatching success was negatively correlated with laying date and the proportion of egg neglect, while overall breeding success was correlated negatively with distance to nearest neighbouring site and positively with the length of the chick‐guard period. Kittiwake breeding success was negatively correlated with laying date. Using seabirds as indicators of marine food supply, breeding success in both species suggested moderate to good food supply in the northeast water polynya in 1993, although at least in the Fulmar the high reproductive output appeared partly maintained by behavioural buffering; long incubation shifts, egg neglect and short chick‐guard periods were symptoms of foraging constraints.