bluuebunny/crossref_metadata_2025 huggingface dataset:
CLUTCH CHARACTERISTICS AND EGG DISCRIMINATIVE ABILITY OF THE AFRICAN VILLAGE WEAVERBIRD PLOCEUS CUCULLATUS
Authors: Victoria J. K.
Published: April 2008

Over a three‐year period, 917 eggs from 27 females were collected from a captive colony of African Village Weaverbirds Ploceus c. cucullatus. A study was made of egg‐laying and incubation behaviour, clutch characteristics and egg recognition.

Fifteen yearling females laid their first clutches at a mean age of 348 days after hatching. The mean clutch‐size was 2.26 in adults and 1.68 in yearlings. The mean clutch replacement interval was 6.6 days in adults and 7.4 days in yearlings with an absolute minimum of 4 days. Eggs were laid at intervals of from 24 to 26 hours beginning usually 2–3 hours after dawn.

The eggs laid by this species vary in ground colour and pattern of spotting between different females, but egg pigmentation is constant for each individual bird. The results of 322 egg‐replacement tests showed that an individual female could recognise her own egg type and would eject from the nest eggs differing markedly from her own. The incidence of rejection was proportional the degree of difference between the eggs. The possible implications for parasitism by the Didric Cuckoo Chrysococcyx cuprius are discussed.
THE EGG WHITE PROTEIN EVIDENCE FOR RATITE AFFINITIES
Authors: Sibley Charles G. , Frelin Christian
Published: April 2008

The egg white proteins of the large ratites (Struthio, Casuarius, Dromaius, Rhea), the kiwis (Apteryx) and several tinamous (Tinamidae) were compared with one another and representatives of several other groups of birds using the technique of isoelectric focusing in acrylamide gel. The tryptic peptides of the ovalbumins of the same groups were compared by thin‐layer electrophoresis. The results indicate that the large ratites are more closely related to one another than any one of them is to any other living bird; that the kiwis are not closely related to any of the other groups with which they were compared; and that the tinamous are not closely related to any of the large ratites but may be distantly related to the Galliformes.
COMPARATIVE ETHOLOGY OF THE CICONIIDAE. THE WOOD‐STORKS (GENERA MYCTERIA AND IBIS)*
Authors: Kahl M. P.
Published: April 2008

This paper reports on an 11‐year study of the comparative behaviour of the four species of wood‐storks. All species were studied under natural conditions at breeding colonies in the U.S.A., East Africa, India, and Indonesia. In addition, observations were made on hand‐reared young of two species (Mycteria americana and Ibis ibis).

Various aspects of signal (display) and non‐signal behaviour are described. The most common ritualised display away from the nest is the Forward Threat. At the neBt, the following displays are seen, mainly during courtship and pair‐formation: Aerial Clattering Threat, Forward Clattering Threat, Snap Display, Anxiety Stretch, Flying Around, Gaping, Balancing Posture, Swaying Twig‐Grasping, Display Preening, Up‐Down, and Copulation Clattering. Each of these patterns is described in the text and many of them are illustrated.

The four species treated here are similar to each other in most behaviour patterns. They do show some quantitative differences in courtship displays, particularly in the Up‐Down, a common “greeting” display shown to the mate at the nest.

The behavioural and morphological evidence now available does not justify the separation of M. americana into a monotypic genus, and I suggest that all four wood‐storks be combined in the genus Mycteria. Thus, the wood‐storks include: M. americana, M. cinerea, M. ibis, and M. leucocephala.
THE IMPORTANCE OF CERTAIN ASSEMBLAGES OF BIRDS AS “INFORMATION‐CENTRES” FOR FOOD‐FINDING
Authors: Ward P. , Zahavi A.
Published: April 2008

Evidence is presented to support the hypothesis that communal roosts, breeding colonies and certain other bird assemblages have been evolved primarily for the efficient exploitation of unevenly‐distributed food sources by serving as “information‐centres”.

Predation‐pressure is regarded as being the most important factor “shaping” the assemblages. The shaping involves the choice of inaccessible or otherwise safe sites, optimum dispersal, mutual awareness of attack and joint defensive tactics, and serves to minimise the vulnerability to predation which would otherwise result when birds mass together in conspicuous, and often predictable centres.
SEA‐BIRDS AT LAGOS AND IN THE GULF OF GUINEA
Authors: Wallace D. I. M.
Published: April 2008

Regular observations of sea‐birds were made in the vicinity of Lagos, southwest Nigeria, between October 1967 and June 1971. Records in the Gulf of Guinea were obtained in April 1969 and, together with others from Ghana and Sierra Leone, were used to complement this study. While few large populations of sea‐birds are supported, the diversity of species occurring at Lagos and over offshore deep water was great. The occurrence of nine species of sea‐bird new to Nigeria was established or confirmed; most of these were also new to West Africa southeast of Gambia. Details are given of fluctuations in numbers these and a further 16 species.

All coastal habitats at Lagos supported a large population of immature Black Terns, and groups of immatures made up a high proportion of observations of other Palaearctic terns and of Royal Terns, which breed only in northwest Africa. In contrast, the Lesser Black‐backed Gulls and Damara Terns reaching Lagos (from breeding grounds almost two continents apart) were mainly adults; both these species are amongst those showing a current increase in numbers. A pronounced spring passage was observed among species including Royal and Sandwich Terns, but adult movements in autumn were not elucidated. The occurrence of the European race of the Little Tern in southwest Nigeria was confirmed, it is at least a regular spring migrant. The frequency of vagrants in January and February was linked to local climate as much to general distribution. Brief comment is also given on immature plumages, and the growing exploitation and pollution of coastal waters.
BIRDS ON ST VINCENT
Authors: Lack D. , Lack E. , Lack P. , Lack A.
Published: April 2008

The land birds seen on St Vincent in 1971 are listed. Chaetura martinica is resident in the rain forest. Two‐fifths or more of the land birds occur in both lowland and highland woodland.
THE GIANT HUMMINGBIRD PATAGONA GIGAS IN ECUADOR
Authors: Ortiz‐Crespo Fernando I.
Published: April 2008

The Giant Hummingbird Patagona gigas was studied in highland Ecuador in 1968–70. The northern and southern limits of its known distribution were extended, but east‐west range and altitudinal limits were as restricted as noted by other authors. Its distribution elsewhere in South America is also reviewed, as are the taxonomy of various populations and breeding records. It is concluded that northern Ecuador is not reached by migrants from central Chile.

Locally, Agave americana was the principal source of nectar, and the Ecuadorian range of the bird corresponds with the distribution of this plant. Further south, where the birds occur over a wider range of elevations, other plants are visited. It is suggested that the availability of nectar and the presence of competitors in combination determine the distribution of the Giant Hummingbird. The Ecuadorian population is probably prevented from northward extension by conditions unsuitable for Agave americana. There is evidence that this plant is exotic to Ecuador; its introduction may have permitted the Giant Hummingbird to expand its range from Peru.
THE FIORDLAND CRESTED PENGUIN EUDYPTES PACHYRHYNCHUS
Authors: Warham John
Published: April 2008

Aspects of the biology of Eudyptes paclzyrhynchus nesting on the west coast of the South Island of New Zealand were studied over six seasons. Nests occur in small scattered groups on steep slopes covered with heavy rainforest, beneath which the birds are protected from temperature extremes.

After about four months at sea, the breeding birds return to land at the height of the southern winter. They aggregate in small, loosely organized groups, breed annually and tend to retain the same nest‐site and mate from year to year. They are ashore to breed for about 20 weeks before their chick departs. Incubation lasts for 31–36 days, and is undertaken in long shifts by both sexes in turn. It does not begin until the second and larger of the two eggs has been laid. The hatchling is guarded by the male for about three weeks, during which time it is fed almost daily by the female parent. The chick then joins a crèche and from then is fed by both parents until, at about 75 days old, it leaves for the sea. The parents also leave thereafter.

Details are given of egg dimensions and weights, of egg loss, rates of chick‐growth, the fate of twins and of the food brought to the chicks. Egg and chick losses are high. The heavy rainfall and frequent storms seem major causes of loss. The birds seem incapable of rearing more than one chick, and when two are hatched a size disparity soon appears leading to the death of the smaller, apparently through starvation.

The adults moult annually in the forest, often on their nests, after some 60 to 80 days spent at sea fattening up for this event. They fast for about 25 days before their new plumage is sufficiently well grown to permit their return to feed. Their whereabouts out of the breeding season are unknown.

Display and associated behaviour are complex. They involve many dramatic attitudes in which the flippers and crests feature prominently accompanied by loud vocalizations.

In an Appendix figures are given for dimensions of breeding pairs and details of other morphological differences between the sexes and between members of the present species and its closely related congener E. robustus.
SYNCHRONOUS FLUCTUATIONS IN POPULATIONS OF SOME RAPTORS AND THEIR PREY
Authors: Galushin Vladimir M.
Published: April 2008

Raptorial birds which depend on a small number of prey species, especially those living in open habitats in the tundra, semi‐desert and desert belts of the Palaearctic, undergo local fluctuations in numbers which are synchronous with the fluctuations in numbers of their main prey species. In this they contrast with the asynchronous or lagging type of predator‐prey oscillation which has received wider attention in the literature.

Evidence from ringing recoveries shows that the species which fluctuate locally in synchrony with their prey tend to move greater distances from their birth‐place or previous breeding place than those with more stable populations. The former species also tend to be split into fewer sub‐specifically distinct forms than the latter. It is argued that the species which are subject to a fluctuating food supply have evolved, as an important adaptation, the ability to undertake more or less extensive ‘searching migrations’, which enable them to find and settle in areas of adequate food supply, often far removed from the previous breeding area. In the longer evolutionary aspect, this ability may be a factor promoting food specialization.

The synchronous population fluctuations of raptorial birds with their prey are compared with the asynchronous or lagging oscillations of carnivorous mammals.
SPRING MIGRATION OVER PUERTO RICO AND THE WESTERN ATLANTIC, A RADAR STUDY
Authors: Richardson W. John
Published: April 2008

Migration over Puerto Rico was recorded by time‐lapse filming of the display of a long‐range surveillance radar on 40 days and 37 nights in the period 2 March‐29 May 1971. Moderate density movements occurred every night; low density movements occurred on most days. Many birds, primarily passerines, took off from Puerto Rico each evening at 20–45 minutes after sunset.

Almost all birds flew to the west, NW or north. Birds were seen approaching from the direction of the Windward Islands and Venezuela, over Puerto Rico, and departing towards the Bahamas and eastern coast of the U.S. Uni‐ and multivariate analyses showed that the number of birds departing W‐N each evening was positively correlated with following winds.

There is less night‐to‐night variation in the amount of migration at Puerto Rico than in eastern North America. However, this is apparently the result of less variable weather in the tropics, not the result of any lesser degree of meteorological selectivity by the migrants.

The tracks of the birds were correlated with wind direction. Birds moved WNW‐NW with NE side winds but NW‐NNW with SE following winds. The tracks were rarely exactly downwind. The variance amongst the directions of individual birds at any given time was usually small and not correlated with cloud cover or magnetic disturbances. The estimated headings of the birds varied from day to day in a pattern suggesting adjustment of headings to compensate at least partially for lateral wind drift.

In autumn many birds approach Puerto Rico from the north or even east of north; in spring few birds moved in the opposite directions. This difference in routes takes advantage of prevailing wind patterns.
THE ENDOCRINE BASIS OF PAIR‐FORMATION BEHAVIOUR IN THE MALE EIDER SOMATERIA MOLLISSIMA
Authors: Gorman Martyn L.
Published: April 2008

Pair‐formation behaviour among the Eiders began after the annual moult, in late September. There was a small peak of display in October and November and a large one in the following April and May. As a result, the female population became paired in two phases, up to 50% in the autumn and the remainder in the following spring.

The seasonal cycle of the abundance of Leydig cells was bimodal, with a peak in October and a large one in April‐May. That the peaks represent increased androgen production was supported by the cycles of Leydig cell enzyme activity and lipid content and of penis weight. The monthly means of Leydig cell abundance and of the rate of display were statistically correlated. Experiments with sexually quiescent males in eclipse plumage demonstrated that testosterone was capable of inducing pair‐formation behaviour.

Relatively advanced stages of spermatogenesis were found in autumn, and were maintained through the winter, complete development occurring in the spring. Seasonal changes in the production of pituitary gonadotropin followed a bimodal pattern with peaks in autumn and in the spring. Field evidence is presented which suggests that Follicle Stimulating Hormone and Luteinizing Hormone were produced at different phases of a circadian rhythm of photosensitivity.
ORDINAL AFFINITIES OF THE AEGIALORNITHIDAE
Authors: Harrison C. J. O.
Published: April 2008

The Aegialornithidae of the Eocene‐Oligocene, previously regarded as swifts, have been transferred by Brodkorb (1971) to the nightjar order Caprimulgiformes. The fossil forelimb bones representing this early family have now been compared with those of recent species of the true swifts and tree swifts (Apodi in Apodiformes) and with nightjars, Oilbirds and frogmouths (Caprimulgiformes). The corresponding bones in swifts differ consistently from those of nightjars in the greater development of various prominences for muscle attachment. In all critical characters the fossil bones resemble those of swifts, and it is concluded that the Aegialornithidae should be reinstated as a family of the Apodiformes.
THE THERMAL SIGNIFICANCE OF THE NEST OF THE SOCIABLE WEAVER PHILETAIRUS SOCIUS: WINTER OBSERVATIONS
Authors: White Fred N. , Bartholomew George A. , Howell Thomas R.
Published: April 2008

The Sociable Weaver of southern Africa builds the largest of all birds' nests. Individual nests contain many chambers and may be occupied by a colony of a hundred or more pairs. Most aspects of the biology of this species are linked, either directly or indirectly, to the nest and its construction. One readily demonstrable function served by this enormous nest is the amelioration of the impact of low environmental temperatures.
ECOLOGY AND BEHAVIOUR OF THE SOUTH GEORGIA PINTAIL ANAS G. GEORGICA
Authors: Weller Milton W.
Published: April 2008

A study of the feeding ecology and breeding biology of the South Georgia Pintail was conducted in East Cumberland Bay during November and December 1971. Of a variety of water areas available, pintails fed and reared their broods in tussock‐trimmed ponds. The second most important feeding areas were sheltered fjords and seashores. Food included freshwater invertebrates such as fairy shrimp, marine amphipods and snails, and small amounts of marine algae. Considering the climatic conditions, the breeding season spans a long season from late October to early March. Courtship and social behaviour are very similar to that of the pintail, and displays and calls could not be differentiated from those of A. g. spinicauda.

There is now one other species of duck on South Georgia, the Speckled Teal, but, because it occurs sympatrically with A. g. spinicauda throughout temperate South America and tends to use different food resources, no serious competition is expected.

It is concluded that these species have successfully adapted to South Georgia because of the availability of protected, food‐rich ponds for rearing young and because of the semimarine adaptations that have developed in Tierra del Fuego and the Falkland Islands.
BIOLOGY AND BEHAVIOUR OF FRIGATEBIRDS FREGATA SPP. ON ALDABRA ATOLL
Authors: Diamond A. W.
Published: April 2008

Both species nested in mixed colonies in mangrove trees. The tops of trees were usually occupied exclusively by minor and the lower parts by ariel, but most nests of both species were in the intermediate parts of the canopy. The main laying season for both species was July to January. A census showed about 27 000 individuals present at the height of the season (1500 breeding pairs of minor, 5350 of ariel). Seasonal variation in numbers could be accounted for almost entirely by the changes in breeding activity of a resident population. Young of both species were fed at or near the nest‐site for at least four months after fledging. A recovery near Bombay of a wing‐tagged immature ariel shows that this species, at least, undergoes a post‐fledging dispersal; it is suggested that young minor either do not disperse, or do so later than ariel.

Food samples collected from chicks showed no overall difference between the species, but a seasonal analysis showed that ariel took more squid than minor in the wet season, and in the dry season the two species took different proportions of the two commonest species of flying‐fish. Chicks of ariel received smaller meals than minor chicks in the wet season, but similar‐sized meals in the dry season; ariel chicks grew more slowly than minor chicks. It is suggested that the timing of the breeding season is related to the need for adults to build up fat reserves to carry them through the courtship, nest‐building and laying periods, when they are tied to the colony and so have little opportunity to feed.

The evidence for non‐annual breeding in frigatebirds is discussed. It is concluded that while successful breeders must breed at intervals of more than 12 months, they could theoretically nest in two successive seasons and that, since breeding success is low, most individuals probably do so.

Existing knowledge of the biology of four of the five recognized species of frigatebirds is summarized, and shows that the family is at least as uniform as the tropicbirds and much more so than other Pelicaniformes.
SUMMER SEABIRD DISTRIBUTIONS IN DRAKE PASSAGE, THE CHILEAN FJORDS AND OFF SOUTHERN SOUTH AMERICA
Authors: Brown R. G. B. , Cooke Fred , Kinnear P. K. , Mills Eric L.
Published: April 2008

The paper summarizes observations on the pelagic distributions of sea‐birds in Drake Passage and off southern South America, collected by ship‐borne observers between December 1969 and April 1970, and in March and April 1972. The birds' distributions have been related to sea surface temperatures and, in the case of the Chilean fjords, to water types defined in terms of temperature and salinity; a partial attempt has been made to relate them to the distribution of the macroplankton.

The boundary between the ranges of Phalacrocorax albiventer and P. atriceps in the Chilean fjords is much farther west than previously reported, and there is some evidence that it has moved westwards within the last 20 years. It is suggested that its position is determined by oceanographic rather than climatic factors.

A sighting of Pterodroma macroptera in Cockburn Channel is the first record of this species for Chile. Exceptionally southerly records of Lobipes lobatus in Magellan Strait, and Pterodroma mollis south of the Antarctic Convergence are also described. An apparent decline in the numbers of Pterodroma neglecta at Masatierra, Juan Fernandez, is noted.
THE OCCURRENCE AND SIGNIFICANCE OF ANOMALOUS REPRODUCTIVE ACTIVITIES IN TWO NORTH AMERICAN NON‐PARASITIC CUCKOOS COCCYZUS SPP.
Authors: Jr Val Nolan , Thompson Charles F.
Published: April 2008

Among the unusual breeding habits of the non‐parasitic Yellow‐billed and Black‐billed Cuckoos of North America are great variability in clutch size and rate of laying, initiation of incubation long before the clutch is complete, occasional laying in nests of other species, annual irregularity in the timing of the breeding season, and semi‐nomadic post‐migratory movements into breeding areas where food is abundant. These facts, in addition to their peculiar diet and the very large size of their eggs, suggest that cuckoos have extraordinary problems in obtaining adequate energy for reproduction.

At Bloomington, Indiana (U.S.A.), during a 15‐year period, anomalies in the reproductive activities of cuckoos were concentrated into two years in which food was abundant. This was particularly true of one of these years, when there was a vast emergence of periodical cicadas: the Yellow‐billed Cuckoo advanced its normal schedule and bred during peak cicada abundance, laid unusually large clutches, and parasitized Black‐billed Cuckoo nests. Some females may have resumed laying in nests in which, having already deposited clutches of normal size, they had been incubating for long periods; the alternative possibility is that there was intraspecific brood parasitism.

The erratic egg‐laying behaviour of these cuckoos is attributed to the evolution of mechanisms permitting very quick exploitation of a favourable feeding situation. It is suggested that reproductive behaviour has become so responsive to an abundance of food that normal ordering and integration of the stages of breeding have been lost in some females. Such a loss could be responsible for the laying of eggs in alien nests, and it may have been the antecedent of obligate brood parasitism in parasitic cuckoo species.
INTRASPECIFIC PREDATION AND COLONIAL BREEDING IN LESSER BLACK‐BACKED GULLS LARUS FUSCUS
Authors: Davis J. W. F. , Dunn E. K.
Published: April 2008

The breeding biology of Lesser Black‐backed Gulls was studied on Skokholm Island, Pembrokeshire, where the number of breeding pairs has been increasing at about 20% per annum since 1963. Laying was found to be synchronous within small groups. Clutch size and breeding success showed seasonal declines over the spread of breeding. The loss mainly of eggs, but to a lesser extent of chicks also, caused this overall decline in success. Hide observations indicated that the bulk of these losses arose through predation by nesting adult Lesser Black‐backed Gulls on their nearest neighbours. Not infrequently the protagonist had lost its own clutch shortly before turning predator, and such a chain‐sequence should lead to a steady build‐up of aggressive failed breeders and so account for the observed seasonal increase in egg loss. Attentiveness to the clutch decreased with season but this was unlikely to have been important in precipitating the predation. Intermediate plant cover was associated with highest nest density and also with highest chick survival. In addition, nest density was directly correlated with chick survival. Whether plant cover and nest density separately affect chick production remains unresolved. Nevertheless, the increasing nest densities in this colony caused by the growth of the gull population are thought to be responsible for the widespread intraspecific predation, the intensity of which is probably a new feature of the gulls' breeding behaviour. The implications of this ‘internal’ predation for laying synchrony and aggregated nesting are discussed; these two factors of the breeding pattern probably evolved largely to combat ‘external’ predators. Not only are they no protection against inter‐neighbour predation but appear to facilitate it. It remains to be seen whether this kind of predation will significantly affect breeding patterns with further increases in nest density.
A TWELVE‐MONTH FIELD STUDY OF THE ALDABRAN FODY FOUDIA EMINENTISSIMA ALDABRANA
Authors: Frith C. B.
Published: April 2008

The Aldabran Fody Foudia eminentissima aldabrana was studied for 12 months on West Island, Aldabra atoll. A complete annual cycle was followed in detail in a small population of marked birds, and observations were made on feeding, courtship, breeding and other behaviour. The breeding season coincided closely with the wet season, when insect abundance was highest.

Although coconut palms and casuarina trees are both thought to have been introduced into Aldabra by man, the fodies preferred both of these trees as nest‐sites to the native vegetation. It is suggested that this may be a recent preference, resulting from excessive predation by introduced rats Rattas rattus on nests in other sites.

In addition to insects and seeds, the Aldabran Fody feeds partly on nectar, and its tongue shows some degree of adaptation to a nectar diet. It is argued that the diversity in bill shape in Foudia cannot be interpreted simply in terms of adaptation for feeding on insects or seeds, but that all three elements in the diet must be considered, in conjunction with the presence or absence of possible competitors.

Adult males defend and maintain nesting territories for most of the year. After breeding, they undergo a full moult and assume an eclipse (female‐type) plumage for a variable length of time, regaining the male breeding plumage after a partial prenuptial moult. A small number of males were found to be aberrant, the red in the plumage being replaced by golden yellow. One such bird showed defective territorial behaviour, and four that were dissected Jacked gonads.

In almost all ways the behaviour and reproductive patterns of the Aldabran Fody are very similar to those of the Madagascar Fody F. madagascariensis. The latter has been introduced onto many Indian Ocean islands, and in view of its similarities to the Aldabran Fody might well be a serious competitor if it were to be introduced onto Aldabra.
PREDATION AND KLEPTOPARASITISM BY SKUAS IN A SHETLAND SEABIRD COLONY
Authors: Andersson Malte
Published: April 2008

Feeding methods and relations of Great Skuas and Arctic Skuas to prey were studied in a seabird colony at Hermaness, Shetland. Great Skuas obtained food by kleptoparasitism, predation and scavenging. They induced Gannets to regurgitate by interfering with their flight; grasping the Gannet by the wing or tail or pushing it down with the feet on its back. Gannets tried to escape by descending to the surface, and regurgitated during 12% of the chases, most frequently when pursued by several birds. Great Skuas caught Puffins by swooping at flocks in the colony. Puffins flying with fish to their young were also chased, releasing food on one fifth of the attacks, or escaping down to the sea and diving. Great Skuas also took Kittiwake nestlings by hovering and grasping the chick with the bill, killing and eating it on the surface. Adult Kittiwakes from nearby nests took to the air, mobbing the predator. More Kittiwakes were engaged in mobbing at unsuccessful than at successful predation attempts, indicating that colonial breeding may be of selective value under such predation. Two different estimates pointed to a Kittiwake nestling predation of 0–12 and 014 young per pair. Fledging success of Kittiwakes was estimated at 0–87‐1‐06 young per pair, considerably lower than at English colonies where predators are absent. In spite of the predation, the Kittiwake colony showed no signs of decrease.

Agonistic behaviour and other evidence indicate that Great Skuas defend feeding territories at the seabird colony. Skuas, gulls and Fulmars competed for food at carcasses. Fulmars dominated and chased away skuas.

Arctic Skuas deprived Puffins of food. They patrolled the cliff, intercepting Puffins arriving with fish, snatching it from their victim's bill, or inducing them to release fish. Puffins continuing their inward flight lost food more often (30%) than birds descending to the sea (15%)—sometimes diving below. This opportunity to escape may explain the lower success of skuas at Hermaness than at a Puffin colony farther inland from the shore (Grant 1971). Other factors being equal, proximity to the sea may thus reduce the risk of kleptoparasitism.
LIGHT INTENSITY AND THE TIMING OF DAILY ACTIVITY OF FINCHES (FRINGILLIDAE)
Authors: Daan Serge
Published: April 2008

The prevailing general theory of entrainment of endogenous circadian rhythms explains variation in the timing of activity with season, latitude and weather conditions on the basis of the dependence of spontaneous frequency of the rhythm on the intensity of constant illumination. In an experiment designed to test the validity of this theory, Greenfinches and chaffinches were exposed to the natural light‐dark cycle alternately in full illumination and in reduced daylight. Contrary to prediction by current hypotheses for these species, in which the spontaneous frequency decreases with decreasing light intensity, their midpoint of daily activity shifted forward when the intensity of natural daylight was reduced. This result refutes the hypothesis that light affects the timing of activity in nature in a manner predictable from its effect in constant conditions.

Both species of finches have a bimodal daily distribution of perch‐hopping activity. The morning peak and evening peak of activity are of about equal strength in winter, but the morning peak increases sharply in the reproductive season. The possibility that the two peaks represent two pacemaker systems, under differential endocrine control, is discussed.

The precision in the timing of daily onset and end of activity is positively correlated with the estimated average rate of change of light intensity at these times of day. Thus, day‐to‐day variations are markedly increased in reduced daylight when activity begins late after sunrise and terminates well before sunset.
ADDITIONAL NOTES ON SUBFOSSIL BIRD REMAINS FROM ASCENSION ISLAND
Authors: Olson Storrs L.
Published: April 2008

More extensive collections of subfossil bird bones from Ascension Island in the South Atlantic further confirm that the former seabird populations of the main island were composed of tropical species still present in greatly reduced numbers, mostly on offshore islets. A single specimen of Puffinus lherminieri provides the first fossil evidence of that species from the island. The extinct flightless rail Atlantisia elpenor was the only land bird certainly known to have been native. A femur, apparently from a vagrant individual, is referred to Porphyrula alleni, A specimen of Nycticorax, much smaller than any recent examples of N. nycticorax seen, is either from an unusually small vagrant or possibly indicates an undescribed endemic species.
FOREST BIRDS OF SOUTHWEST NIGERIA
Authors: Elgood J. H.
Published: April 2008

The presence of 191 species, regarded as forest birds, was sought in ten forest reserves of south‐west Nigeria. One of these reserves, Gambari, some 25 miles south of Ibadan, was visited 60 times and the species encountered each visit were noted. From these two series of data estimates of the dispersal and commonness of each species have been made, though not all the 191 species were met during the study.

A comparison has been made between the forest birds of southwest Nigeria with those of southeast Nigeria as recorded by Serle (1957).

The occurrence of Apalis nigriceps at Sapoba in Mid‐western State and of Parmoptila woodhousei near Lagos are noted as showing a considerable westward extension of their formerly known ranges.
SEASONAL CHANGES IN BODY‐WEIGHT OF OYSTERCATCHERS HAEMATOPUS OSTRALEGUS
Authors: Dare P. J.
Published: April 2008

The body‐weights of Oystercatchers Haematopus ostralegus wintering in Morecambe Bay, north‐west England, showed marked seasonal changes between late summer and late winter, with considerable differences apparent between adult and immature birds. An attempt is made to relate these changes to recorded seasonal variations in prey biomass and to the annual cycles of breeding, moult and migration of the Oystercatcher.

The mean weight of females invariably exceeded the mean weight of males in samples collected on the same dates, regardless of age. Adults returned from northern breeding areas in very lean condition, with mean weights ranging from 526 g in males to 540 g in females. Mean weight then increased progressively, due mainly to fat deposition, to a peak in March (up to 662 g in males and 675 g in females) around the time of their main departures for breeding. Heaviest birds then exceeded 800 g. Birds migrating to Iceland in spring would need to be of above average weight in March to make the shortest crossing (850 km, 13 h), via Scotland, while Oystercatchers of 700 g and over could probably make a direct flight (1500 km, 25 h) from Morecambe Bay in favourable weather. Breeding weights of British Oystercatchers were similar to those of post‐breeders returning to Morecambe Bay in late August.

The mean weights of first‐year Oystercatchers arriving in August were very low, 449 g in males and 478 g in females. Their weights, and those of second‐ and third‐year immatures, then rose rapidly in autumn, with some fat deposition, and reached mean values ranging between 551 g (males) and 597 g (females) by November‐December. Mean weight then fell by 10–17% from December to March returning close to or below the September levels, whereas adults gained a further 6% during these winter months.

Summer and autumn weight gains, and the major moult of adults and older immatures, occurred when the biomass of their two staple mollusc preys, Mytilus edulis (mussel) and Cardium edule (cockle), was maximal. Winter loss in mean weight of immatures corresponded with declining prey biomass, suggesting either that they were less efficient than adults in coping with deteriorating winter food supplies, or that they had no need to accumulate further (premigratory) fat reserves. The autumnal increases in mean weight of immatures are interpreted as an adaptation for withstanding adverse feeding conditions in winter.

The Oystercatcher appears to be the only wader species in Britain in which adults increase, rather than lose, weight during the winter. This may be a consequence of an early breeding season, but it may be regarded also as a measure of the success Oystercatchers have achieved by specializing on a difficult but plentiful prey source.
ABNORMAL PARENTAL BEHAVIOUR OF CAPTIVE MALE WILLOW GROUSE LAGOPUS L. LAGOPUS
Authors: Allen Hugh M.
Published: April 2008

In Willow Grouse Lagopus I. lagopus, as in the other Lagopus species, the hen alone incubates the eggs, leaving the nest only to defaecate and feed. The cock stands nearby to defend the nest area against predators and normally takes no direct part in egg or chick care (Johnsgard 1973, Watson & Jenkins 1964). This note discusses two cases of abnormal incubation and chick care by captive Willow Grouse cocks at the University of Tromsø's Wildlife Research Station.
SEASONAL CHANGES IN NECTAR‐FEEDING BY BIRDS AT ZARIA, NIGERIA
Authors: Pettet Antony
Published: April 2008

Nectar‐feeding of birds was recorded during a phenological study of the woody vegetation at Zaria in the Northern Guinea Savanna of Nigeria.

Throughout the dry season when it is in a non‐breeding state, the Scarlet‐breasted Sunbird Nectarinia senegalensis concentrates on the ornithophilous plants which flower in an overlapping sequence, and exploits the smaller‐flowered species less frequently. As the flowering of the ornithophilous species decreases at the end of the dry season, the range of other plants exploited increases but, in the early rains as the flowering of the indigenous plants tails off, the sunbird switches to ornamental exotics and the indigenous, shrubby parasite, Tapinanthus globiferus. The bird is more conspicuously insectivorous during the wet season when it breeds. The Pygmy Sunbird Anthreptes platura is a breeding, dry‐season visitor which exploits a somewhat different range of small‐flowered, mainly entomophilous species and some exotics but also takes nectar from those ornithophilous species it can exploit, as well as the chiropterophilous Parkia clappertoniana. The bulk of the breeding population leaves the district before the flowering of the indigenous plant tails off. The five other species of sunbird recorded in the district are either very rare residents or more numerous wet‐season visitors and passage migrants for which records of nectar‐feeding are too few to draw conclusions about seasonal changes but the wet‐season visitors appear to rely on the garden exotics in the comparative absence of flowering indigenous plants.

Nectar‐feeding on Bombax costatum and Parkia clappertoniana, where nectar is readily accessible and present in relatively large quantities, was noted for IS species of non‐nectariniid birds, some of which were regular visitors. Some examples of flower consumption probably related to nectar‐feeding are also mentioned.
FACTORS AFFECTING THE AGE OF FIRST BREEDING OF THE KITTIWAKE RISSA TRIDACTYLA
Authors: Wooller R. D. , Coulson J. C.
Published: April 2008

At a Kittiwake colony in Northumberland, 80% of those birds which returned to their natal colony to breed were males and these supplied 52% of all male recruits. More females breed away from their natal colony than males. There was no differences in the proportions of young fledged from sites in the centre or at the edge of the colony, or by parents of different experience, which returned to breed. Kittiwakes breed for the first time at ages from 3 to 8 years, but most at 4 or S years old. Males arrive back at the colony at an earlier age than females and breed for the first time one year earlier. Males obtaining sites at the centre of the colony first breed at an earlier age than those at the edges. Neither the age nor the area of first breeding appear to be transmitted from parent to offspring. Males breeding first aged 4 years or younger produced more young than those which first bred aged 5 years or older, despite their partners laying smaller clutches. This difference was most marked among those males recruited to sites in the centre of the colony. The advantage of this earlier breeding is counteracted by a lower survival rate among those males which start to breed at the younger ages. In all breeding Kittiwakes, annual reproductive output increases with experience while annual survival rates decrease. Once they had started to breed, many birds failed to breed in one subsequent season. Nearly 60% of these cases of intermittent breeding occurred in the year following first breeding. Intermittent breeding was most frequent among young birds and among females. It is suggested that each breeding involves a cost to the individual in terms of reduced survival, and that deferred and intermittent breeding are means of guarding survival. A model is proposed whereby the age at which a bird starts to breed, the nesting site which it obtains, and its subsequent breeding strategy result in each individual producing an optimal number of reproducing offspring in its lifetime, relative to its quality.
THE SIGNIFICANCE OF KLEPTOPARASITISM DURING THE BREEDING SEASON IN A COLONY OF ARCTIC SKUAS STERCORARIUS PARASITICUS IN ICELAND
Authors: ARNASON EINAR , GRANT P. R.
Published: April 2008

Breeding and kleptoparasitism of Arctic Skuas was studied at Vik, Iceland, in 1973. Hatching success was 88.9%; fledging success was 0.27 fledglings per pair. The heavy chick mortality occurred mostly in the first week after hatching. In the early part of the breeding season skuas fed by robbing kittiwakes of their food at sea and by eating arthropods at the breeding grounds. At the time of hatching of skua eggs, which coincided with the hatching of Puffin eggs, skuas switched their feeding activities to kleptoparasitism of Puffins and fish so obtained was the principal item of most skuas' diet thereafter. In the first week post‐hatching, the energy balance of an average adult skua pirating Puffins was estimated to be negative, but changed to positive a week later, although later, coinciding with an influx of non‐breeders it turned back to negative. Arctic Terns which normally breed at Vik, and are exploited by skuas, failed to breed in 1973, and the abnormally heavy chick loss is therefore attributed to this failure of the terns.

The success of the skuas kleptoparasitizing Puffins depends on the proximity of the interactions to the cliff or to the ocean, where Puffins seck refuge. Skuas catch fish mostly in the air, especially if it is dropped from high. Fish dropped from low is mostly taken by competing gulls and Ravens, which mostly control the ground and lower airspace. Skuas chasing in groups enhance their success, but the average success per member decreased with group increase. However, the success of the group‐member in the ‘best’ position was equal to that of a single skua. Puffins carry 1 (large)‐6 (smaller) fish, an approximately equal load irrespective of number of fish. Skuas preferentially chase Puffins carrying ‘large’ fish, thus maximizing their yield per effort. Arctic Skuas responded to changes in the numbers of arriving Puffins with a functional response, but their monitoring of the food supply was far from perfect.
ENVIRONMENTAL INFLUENCES ON GROWTH AND SURVIVAL OF NESTLING HOUSE MARTINS DELICHON URBICA
Authors: BRYANT D. M.
Published: April 2008

Growth of nestling House Martins was studied in relation to (a) conditions in the external environment and (b) aspects of their breeding biology. The dependence of growth performance on (1) hatchling weights, (2) relative difference in hatchling weights within broods, (3) brood size,(4) season, (5) earliness of breeding in relation to other pairs in the colony, (6) timing of breeding in relation to the median breeding week of the colony and (7) aerial food abundance, was investigated by step‐down multiple regression analysis. Up to the stage of the peak brood weight, early laying, small brood sizes and high hatchling weights were associated with higher nestling growth rates. Large relative differences in hatchling weights however tended to depress mean brood weights and increase weight differences (= size hierarchies) within broods. These differences in hatchling weights were considered to contribute significantly to 23% of all nestling deaths, because small, late hatching nestlings suffered very high mortality even when food was abundant. The nestlings which died showed a progressive reduction on growth rates and all succumbed before the 11th nestling day. Because these differences in hatchling weights can be linked to the food supply during laying rather than immediately prior to their death, it is considered that the mortality of these nestlings can ultimately be attributed to the low quality of eggs from which they hatched.

There was a tendency for pre‐hatching factors to diminish in importance throughout growth, while post‐hatching factors increased in importance and, with one exception, were responsible for explaining all the significant variance in the growth characteristics of fledglings. The exception was that differences in wing‐lengths in broods could be linked with weight differences at hatching. Food shortages lowered average brood weights prior to fledging. Because pairs breeding during the median breeding week had lighter young, it was inferred that competition for food during this peak of breeding activity had the effect of lowering nestling growth performance, although the overall effect was considered to be small. Early breeding pairs tended to have larger broods, and these large broods showed a lowered growth performance. However, early breeding pairs had relatively smaller weight and wing‐length differences, in broods of a given size, than occurred in broods of late breeders. It was therefore concluded that early breeding pairs had some attribute which tended to minimize certain disadvantages of large broods. This effect appeared to be linked to the pair, rather than to season or food supply.
THE FORMATION, STRUCTURE AND FUNCTION OF MIXED‐SPECIES INSECTIVOROUS BIRD FLOCKS IN WEST AFRICAN SAVANNA WOODLAND
Authors: GREIG‐SMITH P. W.
Published: April 2008

Mixed‐species flocks of birds were observed during the wet season (July to September 1975) in savanna woodland in Ghana. Thirty‐four flocks contained birds of 56 species in 20 families, including insectivorous, granivorous, and nectarivorous species, using a wide range of foraging methods. Only two species occurred in more than half the flocks. There was no correlation between the number of flocks joined by a species and its abundance in the community.

Among insectivores, but not granivores, the species which joined most flocks were those which habitually occurred in the largest single‐species groups. All stages of breeding activity were represented by the various members. Some species joined flocks only while these were passing through their territories.

Of the two species which were present most frequently, there were no differences between mixed and single‐species flocks for Eremomela pusilla, but Parus leucomelas foraged and called on more occasions in mixed flocks than single‐species flocks, though the rates of foraging and calling were related only to the number of P. leucomelas present.

Groups of P. leucomelas appeared to initiate some flocks by attraction due to their conspicuous wing‐bars, active movement, and loud calls. Black‐and‐white species joined them first, followed by birds of other plumage patterns.

The advantages of mixed flocking are thought to be connected with finding patches of the food of bark‐ and foliage‐searching insectivores, which were the only species regularly seen foraging in the flocks. Because of dry season burning which leaves small unburnt patches of savanna, these insect species may share a common, patchy distribution. Birds may also gain protection from predators, and some species probably gain no advantages.

The species composition and behaviour of flocks previously recorded elsewhere in African savannas are similar to the Ghana flocks.
ECOLOGY OF THE COMMON BABBLER TURDOIDES CAUDATUS
Authors: GASTON A. J.
Published: April 2008

Some aspects of the ecology and behaviour of the Common Babbler are described. The species resembles most other members of the genus Turdoides in being group territorial and exhibiting cooperative breeding. Females remain with their natal group until 6–9 months old and then disperse. Males, in most cases, remain indefinitely in their natal group so that these essentially constitute male clans.

In half of the groups observed only a single pair bred per season, but in some large groups two pairs attempted to breed, one always being unsuccessful, and in other cases one male bred successively with two different females. Overall breeding success was highest for groups in which successive polygyny occurred.

Male non‐breeders fed the nestlings more often than female non‐breeders which were sometimes driven off by the breeding female. A positive correlation was found between the number of non‐breeders feeding the nestlings at day 9–11 and the size of the brood. This probably did not indicate a causal relationship. Breeders in large groups continued to moult while breeding, while those in small groups arrested their primary moult. This difference suggests that assistance from non‐breeders may have had some effect in reducing the physical strain on the breeding pair.

Observed overall survival of adult birds was 63% per annum, but that of the breeding males was 88% per annum. The population declined by 19% during the period of the study, suggesting that observed rates of survival may have been lower than normal.