bluuebunny/crossref_metadata_2025_split huggingface dataset:
POLYGYNY AND BREEDING ECOLOGY OF THE CETTI'S WARBLER CETTIA CETTI
Authors: BIBBY COLIN J. 
Published: April 2008

SummaryMale Cetti's Warblers bred simultaneously with up to three females. Harem size was correlated with size of male but not of his territory. Males occupied large usually exclusive ranges and devoted much time to patrolling and singing often far from their nests. Incubation was solely by the female who also provided most to all of the food for the young. Incubation and fledging periods were prolonged compared with similar sized birds but first nests were unusually successful. Polygynously mated females laid larger clutches than monogamous ones. Males with fewer females took a greater share of feeding but chick growth and survival were not impaired by polygyny, nor did foods brought to the young differ accordingly. The existence of this unusual breeding system is discussed with emphasis on the co‐evolution of sexual dimorphism and non‐equal sex ratios resulting from malemale competition. It is postulated that the linear dispersion of its habitat may especially have favoured operation of the Verner‐Orians polygyny model in the evolutionary history of the Cetti's Warbler.
THE BREEDING BEHAVIOUR AND BIOLOGY OF THE SHORT‐BILLED FORM OF THE WHITE‐TAILED BLACK COCKATOO CALYPTORHYNCHUS FUNEREUS
Authors: SAUNDERS D. A. 
Published: April 2008

SummaryThe breeding biology of the short‐billed form of the White‐tailed Black Cockatoo was studied at two main study areas, Coomallo Creek, an area with large tracts of uncleared lands, and Manmanning, an area of extensive clearing with little native vegetation remaining. The study was based on individually marked birds. The actions of females selecting and preparing their nest hollow ensured that other females were kept away from the area of that nest, resulting in nests being spaced out through the study areas.Eggs were laid between July and November with birds at Manmanning starting about four weeks after those at Coomallo Creek. Clutch size was a maximum of two and incubation took 28–29 days. Hatching success was higher for two‐egg clutches than for one‐egg clutches. There were no differences between fledging success for one‐egg or two‐egg clutches at either area, but fledging success at Manmanning was lower than that of Coomallo Creek.Rates of growth for weight and length of folded left wing were calculated for nestlings from both areas. These rates of growth were compared within areas between years and between areas within years. There were differences in rates of growth of nestlings from Coomallo Creek compared with those from Manmanning and these differences were related to shortages of food at Manmanning.The annual survival of tagged adults was calculated at 61–69% and that of juveniles over the first 12 months after fledging at 15%. The survival figures for adults seemed too low and it is suggested that the wearing of wing‐tags may place the individual at a selective disadvantage compared with an untagged individual.
COLONY DESERTION AND REPRODUCTIVE SYNCHRONY OF BLACK‐BILLED GULLS LARUS BULLERI
Authors: EVANS ROGER M. 
Published: April 2008

SummaryBlack‐billed Gulls breeding in large dense colonies on river beds in New Zealand were found to have a high rate of colony desertion early in the nesting cycle. The hypothesis is developed that individuals faced with possible desertion after they have begun to nest can reduce the likelihood of being deserted by delaying their nesting activities until a large number of others is also ready to nest. This interpretation is developed into a graphic model to show that colony desertion can thereby produce a strong selection pressure favouring highly synchronized nesting. This model successfully predicts onset synchrony, subcolony formation, occurrence of complete colony desertions mainly early in the season, occurrence of partial colony desertions, and the existence of nester non‐nester conflict over whether or not to desert. Unstable food appears to be the most likely cause of colony desertion in Black‐billed Gulls.Black‐billed Gulls are similar, in varying degrees to Sandwich, Royal and White‐fronted Terns. Convergent traits include tendencies to occupy colonies rapidly and synchronously, reduced site tenacity, and the use of open and often unstable nesting habitats. The links described here between desertion and synchrony may be relevant for some other species.
Studies of the courtship behaviour of the Redshank Tringatotanus
Authors: Hale W. G. , Ashcroft R. P. 
Published: April 2008

Ground chases are a feature of early breeding season display in the Redshank. Chases usually involve males chasing females in an attempt to copulate. Fights which occur are usually between male and female and not between two males as recorded in most previous literature. On occasions, females will chase interloping males and fight. Chases may give rise to the wing‐lifting, pre‐copulatory ceremony as may the scraping ceremony which serves to attract a female to a scrape. Ground chases occur most frequently at the end of the first week of April and again at the beginning of the third week. The two peaks in activity coincide with similar peaks in the occurrence of display flights and correspond with two physiologically different groups within the population, early and late breeders. Chases occur most frequently around mid‐day.Scraping takes place mainly in the early breeding season and a single male may produce up to 20 scrapes at this time; later, after egg laying has begun, only a single nest scrape may be produced. The female selects the scrape. Successful copulation does not normally occur until the third week of April and this invariably follows the wing‐lifting ceremony.
The breeding ecology and behaviour of Wrens Troglodytes troglodytes under primaeval and secondary conditions
Authors: Wesolowski Tomasz 
Published: April 2008

The breeding habits of Wrens inhabiting the primaeval forest of Biatowieza National Park, Poland, are described and compared with those of Wrens living in man‐transformed habitats of Western Europe.Significant inter‐habitat differences in numbers exist in Biatowieza. On average there are 4‐3 territories per 10 ha in ash‐alder, 1 ‐7 territories per 10 ha in oak–hornbeam and 0–4 territories per 10 ha in coniferous habitats. In ash–alder stands the males have smaller territories, build fewer nests and have better pairing success than in oak–hornbeam stands. However, these two habitats do not differ significantly in average clutch size, timing of breeding or nesting success. Over 80% of nests used for breeding in Biatowieza are situated in uprooted trees. Inter‐habitat differences in bird numbers reflect differences in distribution and density of such trees.Low numbers of Biatowieza Wrens cannot be accounted for solely by high mortality away from the breeding grounds. Available data strongly suggest that numbers of both sexes are proximately limited by behavioural interactions on the breeding ground.In west European Wrens, densities are higher, territories smaller, polygyny more frequent, clutches smaller and production of young higher than in Biatowieza. Differences in production of young result from different rates of nest predation. Indirect evidence suggests that the breeding habits of Wrens once living in the primaeval forests of western Europe were similar to those of Biatowieza birds, and that the differences observed nowadays result to a large extent from man‐made transformations of habitat. It is suggested that man's lowering of the predation pressure acting both on proximate (enabling birds to produce more young) and ultimate levels (decreasing relative advantages of dispersed breeding) was the decisive factor allowing an increase in numbers of Wrens in secondary habitats.
Habitat and laying date of Great and Blue Tit Parus major and P. caeruleus
Authors: Dhondt Andre A. , Eyckerman Roman , Moermans Renaat , Hublé Jan 
Published: April 2008

Using 19 year's data from nine study areas at Ghent we investigated the effect of habitat on laying date, and found it to be quite different for Great and Blue Tits. In Great Tits we found a clear gradient in laying dates from urban over suburban to rural habitats. Blue Tits laid earliest in a suburban habitat and latest in a rural habitat. All other areas, including urban, suburban and rural ones, formed one intermediate group. The overall average laying date for the Great Tit, 18.9 April, was slightly earlier than that of the Blue Tit, 19.4 April. In urban areas Great Tits laid significantly earlier than Blue Tits, in optimal oak habitat and in one suburban area Blue Tits laid earlier, whereas in the five remaining areas no significant differences between the two species were found.We argue that the differences in laying dates, although correlated to temperature, are probably caused by differences in the timing of food availability. We suggest that differences in laying dates of Great and Blue Tits are caused by a different response to environmental variations through differences in feeding ecology.
Movements of radio‐tagged Grey Herons Ardea cinerea during the breeding season in a large pond area
Authors: VESSEM JANIKE VAN , DRAULAKS DIRK , BONT ANTOON F. DE 
Published: April 2008

This paper describes the strategies of resource utilization in the course of the breeding season by five radio‐tagged Grey Herons Ardea cinerea. The seasonal changes in exploitation of the environment by two breeding adults, one non‐breeding adult and two non‐breeding first‐year birds were studied from March to August 1982, near Zonhoven in Belgium.Two adult breeding birds could be followed continuously from the end of March until the middle of June. During the first month they explored an extended area all around the colony, but each concentrated its search in a specific direction. From the end of April until the beginning of June, most probably from egg‐hatching until the end of breeding activities, each bird spent a very large proportion of its time at a particular feeding site, from which other herons were actively excluded. In the first part of June they again visited different sites, each maintaining its preferred direction. From the middle of June onwards they seemed to have left the fish‐pond area.The pattern of movements of the first‐year birds differed markedly from that of the breeding adults. In April, although both non‐breeding and breeding birds explored large areas, only the areas used by non‐breeders were centred on the colony. From the end of April onwards, probably after general egg‐hatching in the colony, the non‐breeders very rarely revisited the colony, and from May till August their ranges became more and more restricted to very small areas at an increasing distance from the colony. They were never observed defending particular sites.The results are discussed with regard to recent speculations about the evolution of colonies as an adaptation for the exploitation of food resources. Breeding herons seem to explore a large part of the environment during incubation and defend a particular site while feeding their young. Choice of feeding site by non‐breeding birds may be influenced by the site defence of the breeding birds. Non‐breeding birds exploit a large area when breeding birds occupy feeding territories. Perhaps they are forced to forage in less suitable places at this time. Colonies might have evolved as a strategy to minimize effort in resource esploitation as, especially at the beginning of the breeding season, the colony could act as an assembly point in the exploration of the environment. However, its importance as an assembly point diminishes in the course of the season, as non‐breeding birds no longer visit the colony and adults defend territories.
The moult of the Little Stint Calidris minuta in the Kenyan rift valley
Authors: Pearson D. J. 
Published: April 2008

Moult data were collected during 1967–80 from some 6900 Little Stints in the southern Kenyan rift valley.Adults typically moulted from summer to winter body and head plumage during September and early October, soon after arrival. The complete pre‐winter wing and tail moult began in most adults between mid‐September and early October. Some birds finished by December, but others continued until February and March. Individual duration was usually between 100 and 150 days. Adults which completed this moult early often remoulted outer primaries between January and early April.Young birds acquired first‐winter body plumage during October and early November. Some 90% had a complete pre‐winter wing and tail moult. This usually began between December and early February, and finished during March or early April, taking about 70–100 days. In about 10% of young birds, flight feather moult was restricted to the outer primaries and inner secondaries. Birds adopting this strategy typically began moult late, during January or February. Short periods of suspension were common during pre‐winter wing moult, particularly in adults. The difference in moult speed between adult arid first‐winter birds was attributable in the primary, secondary and tail tracts to differences in numbers of growing feathers.Practically all birds completed a pre‐summer moult involving the entire body and head plumage, most of the tertials, some or all of the tail feathers and many wing coverts. Most birds began this moult between early February and late March, and finished between mid‐April and early May. It was typically later and more rapid in first‐year birds than adults. In late birds, the onset of pre‐summer moult was linked to the final stages of pre‐winter moult.The wing moult of the Little Stint in different wintering areas is discussed. First‐winter moult strategy is compared with that in other small Calidris species.
Selection of nest sites by a hole‐nesting duck, the Goldeneye Bucephala clangula
Authors: DOW HILARY , FREDGA SVEN 
Published: April 2008

Nest site preferences were examined for a population of Goldeneye Ducks breeding in nest boxes in Värmland, central Sweden. Some nest boxes were occupied more often than others even if females returning to the same nest box were excluded from the analysis. Nest boxes located higher up trees were occupied more often than those close to the ground and some spatial ‘cluster groups’ of boxes were occupied more often than others. Otherwise nest site prefernces were not related to any measured physical attributes of the boxes. Prefernces for nest boxes seemed to be based mainly on a tendency for females to select those that had been occupied by other females in the preceding year, especially if they had bred successfully. As a result of this, the occupancy of nest boxes was not random over years but rather progressed in a series of runs; a period of consecutive years in which a box was occupied was followed by a period of years in which it was empty.There were reproductive consequences for these prefernces in that females occupying preferred boxes were less likely to lose their clutch to a predator. These females also bred earlier in the year and produced larger clutches and broods than females breeding in other boxes.
Reproductive performance of the Bald Ibis Geronticus calvus in relation to rainfall and grass‐burning
Authors: MANRY D. E. 
Published: April 2008

Reproductive performance of the Bald Ibis Geronticus calvus was studied during three consecutive nesting seasons (1978–80) at a single large breeding colony in Natal, South Africa. A focal sample of 22 nest sites (out of a total of 60 in the colony) was inspected at frequent intervals to determine clutch sizes, egg survival, hatching success, nestling mortality and fledgling production in each year. Mean clutch size was slightly lower in 1980, compared to the two previous years, although survival and hatching success of eggs were similar in all three years. However, nestling mortality was significantly higher in 1980, largely as a result of parental nest desertion and nestling starvation, so that the proportion of breeding pairs producing at least one fledged offspring, and the average brood size at fledging, were lower compared to 1978 and 1979.The 1978 and 1979breeding seasons were both preceded by 12 months of above average rainfall, and Bald Ibises fed extensively on small invertebrates obtained in burnt grassland in the study area during the nesting period. By contrast, the onset of nesting in 1980 followed 11 consecutive months of sub‐normal rainfall. As a result of the drought, and the consequent lack of controlled burning by landowners in the study area in 1980, very little burnt grassland was available during the Bald Ibis' breeding season, and the birds fed primarily in cultivated pastures during the customary burning period. The lower reproductive performance of Bald Ibises at the study site in 1980 is discussed in relation to the possible effects of drought on the abundance of invertebrate prey and the extent of controlled burning in the species' grassland biotope.
The survival of gamebird (Galliformes) chicks in relation to pesticide use on cereals
Authors: RANDS M. R. W. 
Published: April 2008

Field experiments were carried out to test the effects of cereal pesticides (herbicides, fungicides and insecticides) on chick survival of Grey Partridge Perdix perdix, Red‐legged Partridge Alectoris rufa and Pheasant Phasianus colchicus. On fields in experimental plots the outer 6 m of cereal (the headland) were not sprayed with pesticides from 1 January 1984, whereas control plots were fully sprayed. Gamebird brood counts were carried out after the cereal harvest. In addition, nine Grey Partridge broods were radio‐tracked for 21 days after hatching (four in sprayed plots and five in unsprayed plots) to determine their movements, home range size and survival in relation to pesticide spraying.The mean brood size of Grey Partridge and Pheasant was significantly higher on plots where field edges were unsprayed than on fully sprayed control plots. Data for Red‐legged Partridge were inconclusive. The survival of individually marked Grey Partridge broods was negatively related to the distance moved between successive nocturnal roost sites. Survival was significantly higher, the distance moved between roost sites significantly shorter and the proportion of home range including headland significantly greater for broods feeding in spring barley fields with unsprayed field edges compared with broods feeding in fully sprayed fields.
Habitat exploitation and interspecific competition of moulting geese in East Greenland
Authors: MADSEN JESPER , MORTENSEN CHRISTIAN EBBE 
Published: April 2008

Jameson Land, East Greenland is a moulting area of c. 5000 non‐breeding Pink‐footed Geese and 5000 Barnacle Geese. Breeding populations of both species in the area are small and scattered. The moulting Pinkfeet originate from Iceland, and the Barnacle Geese from other parts of East Greenland. Both species arrive in the area at the end of June and moult their remiges in July.Moulting flocks of the two species seldom mix. Pinkfoot flocks are common along coastlines, in wide rivers and on lakes with open views to all sides, while Barnacle Geese predominate in smaller rivers and on lakes with surrounding hills. During moult the geese, and especially the Pinkfeet, are extremely wary and depend on a safe area of water serving as a refuge with nearby food supplies (sedge‐dominated marshes). Barnacle Geese graze in a zone 0–100 m from the refuge, Pinkfeet up to 200–250 m from the refuge. The moulting sites fill up with geese according to available marsh areas, and the grazing pressure on average amounts to 594 goose‐days per ha during the moulting period. Food intake is estimated at 149 g and 138 g organic material per 24 h by Pinkfeet and Barnacle Geese, respectively, [n 1984, which was sunny and warm, net above‐ground primary production of a Carex subspathacea marsh (the prime feeding ground during moult) from the beginning of growth to the end of July was 13–15 g dw m2, and it is estimated that the geese consumed 60–69% of the production. In 1983, which was cold, geese probably consumed the entire production. Goose grazing did not affect productivity, but nutrient levels were high in grazed compared with ungrazed shoots, and peaked in early July.When separate, the diet of both species comprises sedges and grasses. Where the species co‐exist the amount of mosses in the diet increases, especially in Barnacle Geese. With respect to nutrient and fibre contents, moss is a suboptimal food compared to sedges and grasses. When separate, the geese spend 41–46% of the 24 hr grazing. Where they co‐exist, Barnacle Geese spend 62% of the time grazing, while Pinkfeet seem unaffected by the presence of Barnacle Geese.It is argued that carrying capacity for moulting geese is reached. Geese compete for resources, the Barnacle Goose suffering from the presence of the other. The observed distribution pattern is suggested to result from (1) Pinkfeet being limited to certain sites due to extreme wariness, and (2) Barnacle Geese trying to avoid competition by utilizing sites which Pinkfeet are reluctant to use. The experience of older Barnacle Geese of stress when settling with Pinkfeet may be the segregation mechanism.Moult coincides with the onset of growth and peak nutrient levels in the vegetation. It is suggested that the geese undertake moult migrations to Jameson Land both to avoid competition for resources with breeding geese and because they gain advantage from a growing, nutritious vegetation.
A comparison of breeding and moult cycles and life histories in two tropical starling species: the Blue‐eared Glossy Starling Lamprotornis chalybaeus and Rüppell's Long‐tailed Glossy Starling L. purpuropterus
Authors: DITTAMI JOHN P. 
Published: April 2008

The Blue‐eared Glossy Starling Lamprotornis chalybaeus and Rüppell's Long‐tailed Glossy Starling Lamprotornis purpuropterus were investigated in the field and in aviaries at Lake Nakuru National Park, Kenya for seasonality in reproductive activity and moult. The former species was found to be a seasonal breeder which nests after the onset of the heavy rains in April. Although some birds had large gonads prior to the rains in the dry season no nesting occurred. The rains were contemporary with increases in gonadal size and the plasma titres of LH, testosterone (T) in males and estradiol (E2) in females. These hormones are associated with the initiation of breeding activity. As breeding ceased in July and the moult began, the plasma titres again decreased. There was a bimodal breeding pattern which paralleled a change in biotope preference for nesting. Early nests, in the heavy rains, were on the open savanna and later nests were in the acacia forest. Late nesting birds also had delayed peaks in gonadal size, plasma titres of LH, T and E2 and a delayed moult onset. Data on individual captive birds demonstrate that these annual cycles have a distinctly individual character superimposed on the seasonal trends.In Rüppell's Long‐tailed Glossy Starlings no seasonality in breeding was found although the flight feather moult commenced and was completed in all individuals at about the same time. The moult extended over about ten months, so a great deal of breeding‐moult overlap was present. The absence of seasonality in field birds was reflected in the aviary birds, which had no pronounced cycles in the reproductive parameters measured (gonadal size, LH, T and E2 plasma titres). Breeding in field birds was regulated on a pair basis and correlated with increases in duetting. The striking differences in the seasonal organization between this species and Blue‐eared Glossy Starlings were presumably due to the different biotope preferences and social behaviour of the two species.