bluuebunny/crossref_metadata_2025 huggingface dataset:
BREEDING SEASONS IN THE GALAPAGOS.
Authors: Lack David
Published: April 2008

The Galapagos are on the equator. In the cool and cloudy dry season the south‐east trade wind blows and the cold Humboldt current flows strongly round the islands. In the rainy season, which is very variable but usually lasts from about January to April, the weather is calm, warm and sunny, with periodic heavy rain, while the northern boundary between the Humboldt current and the warm Pacific drift is further south, in some years south of the Galapagos.

Captive Geospizinae are capable of breeding throughout the year, but in the Galapagos these finches, like the other passerine birds, breed only in the rainy season. Rain appears to stimulate their sexual behaviour. Some abnormal breeding in September 1906 is discussed.

The dove starts and stops breeding about two months after the passerine birds, but mainly overlaps with them, in March and April.

The hawk and short‐eared owl have young in the cool dry season after the rains, as do large raptors in Africa.

The duck and the herons breed in the rainy season, but also in August and September.

Many species of sea‐birds breed nearly throughout the year, but five of the six Procellarii have their young in the cool dry season when the Humboldt current flows most strongly round the islands.

The gull Larus fuliginosus breeds about November, i.e. at a different season from, all other Galapagos birds (including the other species of gull), but at the same season as the related L. modestus on the adjacent mainland of South America.
THE BIRDS OF SÁO TOMÉ AND PRINCIPE IN THE GULF OF GUINEA.
Authors: Snow. D. W.
Published: April 2008

A short account is given of what has hitherto been known of the birds of the islands of SÁo Tomé and Principe in the Gulf of Guinea.

 A short visit was paid to these islands in September and October 1949. Field notes are presented on a number of species, about which nothing has previously been written.

 It is shown that the land birds of the two islands are strikingly different, and that on both islands it is the endemic species which are most abundant, while the non‐endemic species seem to be more liable to extinction.

 There is evidence that a great outburst of breeding was commencing at the time of the visit, which coincided with the end of the dry season.
THE BREEDING SEASONS OF AFRICAN BIRDS—2. SEA BIRDS.
Authors: Moreau. R. E.
Published: April 2008

1. All the available data, largely unpublished, are assembled for sea‐birds breeding in African waters, about 36° N.‐36° S.

2. An ill‐defined breeding season by any species at any station is exceptional.

3. North of the Equator practically all sea‐birds breed in spring or summer.

4. South of the Equator there is much more variation. Round the Cape there is a good deal of mid‐winter breeding, mainly in stations affected by the warm Agulhas current.

5. On the east coast most of the breeding takes place in the period June–August from the Gulf of Suez (27° N.) to the mouth of the Zambesi (19° S.) and beyond,i.e.in the hottest months north of the Equator and the coolest months south of it.
THE BREEDING BIOLOGY OF THE SWIFT APUS APUS
Authors: David  , Lack Elizabeth
Published: April 2008

1. The Swift Apus apus was studied round Oxford 1946‐50, for the last three years in nesting boxes.

2. The adult weight greatly varies with the weather, and is heavier in May than later in the summer.

3. The clutch‐size in England is two, sometimes three, the proportion of clutches with three eggs differing markedly in different years. Average clutch‐size is higher in Switzerland than in either England or Fenno‐Scandia, and is lower late in the season.

4. The average weight of the eggs in May differed in different years. The second egg of the clutch is usually heavier than the first.

5. The apparent incubation period is several days longer if there is bad weather at the start.

6. Nestling mortality is higher in large than small broods. It is also higher in bad than in good weather, the harmful influence of bad weather being much greater in large than in small broods. In three bad summers the broods of two produced more young per brood than did the broods of three, but in two good summers the broods of three produced a larger average per brood.

7. The nestling period is remarkably variable (35–56 days), being longer in bad weather.

8. The young increase to a peak weight well above that of the adult and then gradually get lighter. This general trend is interrupted by marked losses on days of bad weather when the parents bring little food, and the weight averages for different periods vary markedly in relation to the weather.

9. The wing‐feathers grow more slowly in undernourished than well nourished nestlings. Retardation at one period does not prevent rapid growth later.

10. The daily increase in nestling weight is higher with sunshine and warm temperatures and lower with rain and wind.

11. At Oxford individual meals were of similar size in good and in poor weather, but the feeding frequency was higher in good than in poor weather.

12. The feeding frequency is higher in broods of larger size, but it does not increase proportionately, so that individual nestlings receive fewer feeds in large than in small broods. The increase in feeding frequency with better weather is least in broods of one and greatest in broods of three.

13. In Switzerland, where the weather is usually finer than in England, the average clutch‐size is higher than in England, nestling survival from broods of three is higher, the nestlings are heavier, and the meals are probably heavier, but other measurements are similar in the two countries.

14. Swifts differ from small passerine birds and resemble Procellarii in having a smaller clutch‐size, longer incubation and nestling periods, a peak nestling weight well above, instead of similar to, that of the adult, a widely variable nestling period, a marked ability to withstand starvation and a capacity to retard feather development when undernourished. All these points can be related to the fact that Swifts and Petrels have safe nesting sites but an uncertain food supply, whereas small passerines are raised when food is dependable but predation is high.
NOTES ON THE LONG–BILL LARK CERTHILAUDA CURVIROSTRIS.
Authors: Macdonald. J. D.
Published: April 2008

Personal observations are given on habits, habitat, and notes of Certlmlauda curvirostris.

 Certain call–notes may be connected with the feeding of juvenals and the keeping together of family parties.

 Breeding cycle is correlated with latitude.

 There are grounds for accepting two forms of Long–bill Lark in South West Africa and all the forms of Long–bill Larks as geographical races of one species, including C. subcoronata Smith and C. falcirostris Reichenow.

 In all, seven geographical races are recognizable in specimens in the National Collection. Other races have been described whose validity has not been checked.
EXPERIMENTS ON BIRD ORIENTATION *.
Authors: Kramer. Gustav
Published: April 2008

The Starling's ability to reproduce constant compass directions has been demonstrated in two ways: (1) by using the migratory activity as an indicator: the bird tends in a constant direction; (2) by training the bird to choose one of several (up to 12) feeders, symmetrically distributed round the experimental cage. If the incidence of light is changed by use of a mirror arrangement, the direction chosen by the Starling changes correspondingly. More particularly, it has been proved that the sun is the governing factor. The orientation faculty (in experimental conditions) vanishes if the sun is hidden.

The correct direction is reproduced regardless of the time of day. Care has been taken to confirm this ability to allow for the daily movement of the sun. The bird is shown to respond correctly even to an artificial sun with fixed azimuth‐position. In this case the direction indicated by the bird is not constant in relation to the compass, but changes progressively, following the sun's path in the reverse sense.

The explanatory value of the sun orientation is discussed. At the present stage of our knowledge other orientation mechanisms besides that demonstrated here must be considered. Particularly it is thought that orientation by night in terms of the sun‐orientation is not satisfactory.

New experiments itre described which show that homing pigeons are able to home straightaway over an unknown stretch of 200 miles. Some sort of astronomical navigation is suggested by the fact that the pigeons seem to be orientated even before starting. Several other hypotheses are clearly ruled out. Sun‐navigation is being taken as a working hypothesis in further experiments.

Apart from this orientation method, direction‐learning can be produced by training the pigeons along one homing line. By displacing the birds sideways they are misled, this being the test of direction‐learning.

Pigeons, like Starlings, can be trained to choose food from a definite direction under experimental conditions. Here, too, the sun is the physical clue for orientation. In pigeons, too, the ability to compensate for the daily sun‐movement has been demonstrated.
VISIBLE MIGRATION IN THE BRITISH ISLES: A REVIEW
Authors: Snow D. W.
Published: April 2008

This paper aims to bring together the chief observations that have been recorded so far on visible migration in the British Isles.

The autumn movements that have been seen on the various coasts, and inland, are briefly described, and the few spring observations are summarized.

Maps show the directions which migrating Corvidae, Starlings, Chaffinches and Skylarks have been seen to take in autumn, and there is some discussion of the autumn movements of these four species. The observed movements of some of the other chief passerines, and of the Wood‐pigeon, Stock‐dove and Lapwing, are more briefly mentioned.

Some of the differences in the migratory behaviour of different species are mentioned, and some of the most obvious gaps in knowledge of visible migration in the British Isles are pointed out.
A POSSIBLE MOULT‐MIGRATION OF PINK‐FOOTED GEESE.
Authors: Taylor. Julian
Published: April 2008

Pinkfeet were seen in fair numbers in the area north of the Hofsjokull in June and July 1952.

 It is unlikely that any of these nested, probably because of the snow at the end of May and the coldness of June.

 It is suggested that this area north of Hofsjokull is in the process of being colonised.

 Many geese moved north‐west at the end of June and beginning of July. This is a movement just prior to the moult and involves desertion of the normal habitats of Iceland. It is more likely that the birds flew to Greenland rather than to the north of Iceland.
BREEDING OF THE FULMAR FULMARUS GLACIALIS
Authors: Carrick Robert , Dunnet. George M.
Published: April 2008

.1. A study of individually marked Fulmars during three seasons has shown that both sexes can breed in successive years. The evidence for the theory of intermittent breeding is examined and definitions are given of the various categories of birds which compose the population during the breeding season. It is suggested that the supposed non‐breeding adults which are seen, often in moult, in July are failed‐breeders which have lost their egg or nestling.

2. No marked individual changed its nest‐site between years, although the number and identity of sites occupied each July varied considerably.

3. No changes of mate occurred among the six marked pairs which nested in two consecutive years.

4. There is some evidence that both parents remain near the colony during the week before and after hatching.

5. Analysis of the 90 known sites of a colony subject to avian but not wild mammalian predation has revealed a wide range of habitat selection and a strong tendency toward close concentration of nests.

6. There is some evidence that the breeding season, as measured by date of hatching, varies from year to year.
TAWNY OWLS AND THEIR PREY
Authors: Southern H. N.
Published: April 2008

1. This paper follows over eight years the diet of some 20 pairs of Tawny Owls Strix aluco living in woodland.

2. Pellets were collected regularly and the prey‐remains in them were identified. Much information about the territorial and hunting habits of Tawny Owls was gained.

3. There is a regular seasonal swing between small rodents (especially Wood Mice and Bank Voles) and larger prey (young Moles, Rabbits and rats). The former predominate in winter and spring, the latter in summer and autumn. This fluctuation is regular year after year with these animals, whereas shrews and small birds are eaten in small numbers steadily throughout the year and from year to year.

4. Small rodents are eaten most when ground cover is sparsest, which may account for the early breeding season of the Tawny Owl. By the beginning of May, when vegetation is becoming dense and mice and voles are difficult to find, the young are already well‐grown and can deal with the food brought to them. The hen is, therefore, free to go hunting herself and both parents must work hard for the next three months while the young are still dependent on them.

In more open country Barn and Short‐eared Owls seem to time their breeding later so that they are feeding their young on the big crops of Short‐tailed Voles and–to a smaller extent–of shrews.

5. This long period of dependence of young Tawny Owls falls when there are plenty of young Moles, often a large crop of cockchafers and generally plenty of earthworms to fall back on. The brownish, fibrous pellets of Tawny Owls are now known to contain mainly the chaetae of earthworms, which are sometimes brought to the young in very large quantities.

6. Analysis of the results by locality shows that Tawny Owls take only the prey species which are available in their immediate vicinity. This and other evidence proves them to be strongly territorial and it is suggested that only by having a territory and knowing it intimately can a Tawny Owl survive.
THE BEHAVIOUR OF BIRDS IN CONTINUOUS DAYLIGHT
Authors: Armstrong Edward A.
Published: April 2008

The Strigiformes and Charadriiformes tend to be more persistently active in continuous daylight than the Falconiformes.

In Lapland at midsummer passerine song reaches a minimum a few hours before midnight and a maximum in the hours immediately following midnight. The song‐lull cannot be equated with the quiescent period.

The quiescent period of three species, studied at the nest, the Willow Tit, Fieldfare and Dipper, occurs at different times.

There is evidence that the nestling period of some passerines is shorter in the arctic than in lower latitudes‐suggesting, ceteris paribus, an inverse relationship between length of the nestling period and length of daylight.

Light appears to be the dominant external factor governing bird activity in the arctic.

The coloration of many species is correlated with the extent to which they are active in dim light. The continuous daylight of the arctic summer accentuates the adaptive value of cryptic coloration to open‐nesting birds vulnerable to predatory birds.
THE DIURNAL RHYTHM OF BIRDS IN THE ARCTIC SUMMER
Authors: Cullen J. M.
Published: April 2008

The diurnal rhythm of various activities in three species of sea birds was studied in the island of Jan Mayen (lat. 71o N.) in July and August 1950.

The number of Fulmars flying past a certain point decreased strongly around midnight in July and even more markedly in August.

In Brünnich's Guillemot the number of birds alighting at a colony fluctuated but it was uncertain whether the fluctuations were regular or not.

On the other hand the number of young of the same species leaving their nesting ledges showed a very marked peak during the hours preceding midnight. This peak coincided with a peak at the same place in the numbers of Glaucous Gulls, which preyed on the young guillemots as they flew down to the water.

The amount of sleeping and preening by Kittiwakes at a nesting cliff fluctuated little during the 24 hours in July (when they slept about 7 hours a day) but more in August.

The “ultimate factors” responsible for the rhythms observed in Jan Mayen are discussed.

The duration of sleep is discussed for the birds studied, and compared with that of other species.
FEEDING ECOLOGY OF TITS, WITH NOTES ON TREECREEPER AND GOLDCREST.
Authors: Gibb John
Published: April 2008

The feeding habits of the titmice, Treecreeper and Goldcrest were studied in a mixed broad‐leaved wood near Oxford, from April 1950 to August 1951, by means of repeated standard observations.

The proportion of time spent feeding varied inversely with the body‐weight of the species. A greater proportion of the time was spent feeding in mid‐winter, and in the breeding season when young were being fed, than in spring or autumn. Feeding intensity varied similarly.

Fighting for food was recorded most often in mid‐winter, and rarely in summer. Most attacks were intraspecific. Probably individuals gain or lose much food by fighting.

Although adult birds search for food most of the time when feeding young, they preen then as often as at other times.

The period and intensity of singing and calling was measured. This was often performed concurrently with other activities–mainly feeding–in the tits, least often by Great Tits, most often by Coal Tits.

Distant flight was more often recorded in winter than in summer.

The frequency with which the birds fed (a) in different species of trees and shrubs, and (6) at different feeding stations, varied significantly from month to month. The behaviour of the birds is described. The Parus species fed most diversely in autumn, and least diversely in early summer. Coal and Marsh Tits fed more diversely than Great and Blue Tits, which in turn fed more diversely than Longtailed Tits and Goldcrests.

The tit species were more distinctly segregated from each other by feeding habit in winter than in summer.

Food was especially short in mid‐winter and in the breeding season, and competition for food was most severe in mid‐winter. Hence mortality from food shortage is probably more density‐dependent in winter than in summer.

Although the several tit species have much in common, and often eat the same foods, each species has evolved characteristic methods of feeding, with corresponding structural adaptations; and each species occupies a more or less distinct feeding‐niche.
DURATION OF PARENTAL ATTENTIVENESS IN THE SOOTY SHEARWATER.
Authors: Richdale L. E.
Published: April 2008

Parental attentiveness in. the Sooty Shearwater Puffinus griseus was studied on Whero Island, near Stewart Island, New Zealand, in 1951‐52 and 1952‐53. In the first year 30 chicks were watched from 18 March until they left the burrow, and in the second year 57 chicks from 10 February (i.e. for practically the whole of the chick stage).

The chief feature of the pre‐desertion period is the irregularity of parental attention (with wide individual variation). Inattentive periods range from 1 to 25 days (mean 4‐3), attentive from 1 to 11 days (mean 2–4).

From 10 February to 31 March 1953, 13%‐65% (mean 37‐2%) of the chicks were visited nightly by parents; from 1 April to 18 April, 13%˜46% (mean 27'5%); and from 19 April to 4 May, 0 %–11 % (mean 3%). In the second period 43 chicks (76‐8%) were deserted by their parents, and in the third period all the remaining 13 chicks.

Of 83 chicks which survived to leave the burrow in the 1951‐52 and 1952‐53 seasons, 58 (70%) left weighing more than 455 grams and 25 (30%) weighing less. Only the former group of chicks was believed to survive.

Parents desert the breeding area in any given season apparently in answer to a migration urge, irrespective of the chick's age. Chicks hatched late therefore have little chance of survival.

The length of time a chick remains in the burrow varies from 86 to 106 days (mean 97). The chicks leave the burrow apparently in answer to an internal urge, irrespective of the degree of parental attention.

Before finally leaving the burrows, chicks may emerge at night and then return. Chicks more than 455 grams at departure emerged from 0 to 14 nights (mean 5–9 nights).

The length of the desertion period is much shorter than we have been led to believe. For 58 normal chicks the period ranged from 0 to 27 days (mean 12 days). Chicks have been known to be fed just before departure and birds assumed to be parents have been known to enter the burrow after the chick has departed. If so, this means that these chicks departed in an inattentive period by the parent.

The presence or otherwise of a desertion period in petrels depends on whether or not the species concerned is migratory. For example, as far as is known, migratory shearwaters have a short desertion period, but the non‐migratory Royal Albatross and other species have not.
DISPLAY OF THE HOUSE‐SPARROW PASSER DOMESTICUS.
Authors: Summers‐Smith D.
Published: April 2008

Various forms of non‐communal display in the House‐sparrow are described. Pair formation is initiated by the male, which selects a nest‐site and displays beside it to attract a female. It is suggested that the display of a single male towards a female away from the nest is an intensive form of pair‐formation display and not, as has been suggested, an invitation to coition. The behaviour during coition, presentation and nest‐relief ceremonies, fledging behaviour, threat and aerial chasing are also discussed. The relationship between the displays and the posturings used in them is discussed.
THE BREEDING AND FEEDING OF JACKDAWS AND ROOKS WITH NOTES ON CARRION CROWS AND OTHER CORVIDAE.
Authors: Lockie J. D.
Published: April 2008

The nestling food and breeding of Jackdaws, Rooks, and to a lesser extent Carrion Crows were studied at Oxford from 1952 to 1954.

 The average clutch‐size in the Jackdaw is 4–4 and in the Rook 4–3. Late clutches are significantly lower than early in the Rook but not in the Jackdaw. Annual variation in clutch‐size is small.

 In both Rook and Jackdaw the survival of nestlings decreases as brood‐size increases. Predation, disease, and nest‐site are unimportant in producing this mortality; food‐shortage is very important.

 In Jackdaws and Rooks the eggs hatch asynchronously and this is an adaptation to a variable food‐supply; by the speedy elimination of the small young in a brood when food is short, the brood is brought into closer correspondence with the food‐supply.

 In the Jackdaw and Rook the brood‐size which effectively produces most young lies between four and five. This corresponds to the average clutch.

 Rooks typically probe in grassland where they obtain earthworms which form the bulk of the food brought to nestlings. April is on average the best month for obtaining earthworms on grassland (or suitable alternative food) and this is the month when most young Rooks are in the nest. Jackdaws feed on the surface of open grassy places and have their young in the nest when many of the varied invertebrates in this habitat are most abundantly available. Carrion Crows feed partly in woods and partly on grassland. The nestlings are fed mainly on earthworms, nestling birds and small mammals.

 The breeding season of the Jackdaw and Rook varies little from year to year. The food‐supply is unlikely to be a major factor in initiating ovulation since its season of abundance is variable.
TERRITORY IN THE THICK‐BILLED NUTCRACKER NUCIFRAGA CARYOCATACTES.
Authors: Swanberg P. O.
Published: April 2008

The main features of the territory in the Thick‐billed Nutcracker are:‐ (a) the territory is kept for life and inhabited throughout the year; (b) the special food, nuts, is stored in the territory; (c) song, copulation, nest‐site selection and nest‐building take place only in the territory; (d) territories examined were 11.2–14.9 hectares, averaging 32.7 acres, believed to be the normal size in Sweden.

There is no clear evidence that the territory has the function of securing more than a certain amount of food other than stored.

The territory is respected by other Nutcrackers as to its main functions, while simple visits by other Nutcrackers and ceremonial gatherings in the territory are tolerated.

Both territory‐holders attack intruders that try to take nuts but as they do not chase them out the behaviour is not regarded as truly territorial behaviour.

The territory is proclaimed by the calls, the song being exclusively sexual.

Unmated birds have not been recorded with territorial behaviour.

When the special food is limited and the nesting habitat ample, the population is limited by the amount of the special food; but when the special food is abundant and the nesting habitat limited, over‐crowding seems to be prevented by territorial behaviour.

It is suggested that the function of territory in the Nutcracker is to give the holders a well‐known refuge from predators, to serve as a food storing place, and by spacing out to prevent these positive qualities from reduction by overcrowding.
TERRITORIAL ACTIVITIES OF THE AMERICAN ROBIN TURDUS MIGRATORIUS.
Authors: Young Howard
Published: April 2008

American Robins show territorial behaviour in the springtime by partially isolating themselves on areas and displaying intolerance of varying degrees towards intruders. Territories are established by the males; the females later help in maintaining the boundaries. These boundaries are not precisely defined, and claimed areas often overlap. Excessive trespass and frequent fights are characteristic in this species. Inter‐sexual combat occurs, and the males are dominant to the females. Possible functions of territory in this species include:helping to ensure a food supply, enhancing the opportunities for mating by dispersal of the males, and maintenance of the pair bond.
RECENT FIELD OBSERVATIONS FROM IRAQ.
Authors: Chapman E. A. , McGeoch J. A.
Published: April 2008

The paper includes an introduction to, and a systematic list of observations made in Iraq from August 1952 to August 1954. At least six species appear to have been added to the Iraq list, and at least six breeding species to the list of breeding birds in Iraq. The extension of breeding range, winter range, summer range and breeding seasons of several species is discussed. The migratory seasons of many species are noted and the westerly passage of Hirundinidae and Motacilla sp. in late summer is recorded.
A SPECIFIC CHECK LIST OF THE BIRDS OF GREECE.
Authors: Lambert Anthony
Published: April 2008

This paper consists of a catalogue of all species known to occur in Greece. Indications are given of the status, distribution and relative abundance of all these (except rare vagrants and accidentals), in the north, centre and south of the country, and of the habitat or habitats in which they are generally found. The notes on each species are based on the studies mentioned in the list of references and on personal knowledge of the country gained during three years' residence from 1952–1955.
EXPERIMENTS ON BIRD ORIENTATION AND THEIR INTERPRETATION.
Authors: Kramer Gustav
Published: April 2008

Among birds, the ability of sun‐azimuth orientation has been demonstrated experimentally in Starlings Sturnus vulgaris, Meadow Larks Sturnella magna, Barred Warblers Sylvia nisoria, Red‐backed Shrikes Lanius collurio and homing pigeons. Sun‐azimuth orientation consists in determining compass directions by the sun position regardless of time of day, hence mainly in the ability of correcting for the sun's daily azimuth displacement

Evidence indicating the innateness of the underlying mechanism is not complete, but suggestive

The estimation of the sun's speed must be considerably independent of personal experience. Individual Starlings differ in appraising the hourly angle of displacement in spite of their being constantly exposed to the natural sun

The internal clock which is normally in phase with the astronomical day‐night cycle can be controlled and shifted by an artificial light‐dark cycle. The bird shows the deviation of its personal clock by producing determinate direction choices. The direction choices are equal to those produced by birds kept in outdoor conditions if the artificial light‐dark change is synchronized with the astronomical day‐night cycle. They deviate in a predictable manner if the artificial cycle is shifted. A shift by six hours results in a final directional deviation of roughly 90°. An exposure of 4–12 days to the phase‐shifted light‐dark cycle is sufficient to attain the full shift of the internal clock, which demonstrates that its “rigidity” is limited

Recent advances in the problem of night orientation are reviewed. There is strong evidence of orientation by stars. The most convincing fact is oriented migratory activity under an artificial sky (planetarium)

Recent facts are submitted supporting the ability of directed homing independent of familiar landmarks. At least in some areas the homing success depends upon the direction of displacement

In the winter months a marked weakening of the homing ability of homing pigeons is observed in Northern Germany, at distances of 14–50 miles

Overcast skies handicap both homing success and initial orientation at distances down to 7‐5 miles

Day‐to‐day variations in homing success are observed which cannot be explained in terms of traditional meteorology

No direct evidence for bi‐coordinate sun‐navigation is available. The hypothesis of sun‐arc navigation, based upon the observation of very short sections of the sun's path, is criticized theoretically. The main supporting experiments are re‐analyzed; one of them has been repeated and could hot be confirmed. On the whole the evidence in favour of this hypothesis is considered insufficient

The explanation of homing orientation is still lacking. Prospects for a future experimental approach are discussed.
THE BREEDING OF THE BLACKBIRD TURDUS MERULA AT OXFORD
Authors: Snow D. W.
Published: April 2008

1. Breeding statistics are given for a garden population of Blackbirds, and less complete data for a woodland population. Comparison is also made with data provided by the British Trust for Ornithology nest‐record cards.

2. The breeding season lasts from March to June. Temperature influences the timing of the start of breeding, and rainfall probably influences the ending of breeding. Yearling females tend to begin to breed later than old females and to stop a little earlier. Old females averaged 3·1 broods per year, yearling females 2·3. Breeding begins later in woodland than in gardens.

3. Yearling females lay smaller clutches than old females. Clutches are on average smaller in gardens than in woodland. Smaller clutches are laid when the weather is cold and perhaps also when it is very dry.

4. Incubation starts gradually while the clutch is being laid. Consequently hatching is usually spread over a period of a day or two. Hatching success was about 90% in gardens, old parents being more successful than yearlings. Hatching success in woodland was 92 to 95%.

5. In gardens, nestlings are fed mainly on earthworms in the early part of the breeding season, later on a greater variety of food, especially insects. In droughts food is hard to find and many nestlings die. In woodland, nestlings are fed especially on green caterpillars and a variety of other invertebrates taken from the woodland floor, and few were found to die in the nest.

6. The young grow from about 6 gm. to 70 gm. The last‐hatched are often much lighter than the first‐hatched. If food is short, the lightest young usually die one by one. The weight of eight‐day‐old nestlings is highest in the middle of the breeding season. Young from large broods are on average heavier than young from small broods. The flight feathers emerge at the age of seven or eight days, but may be delayed for up to two days by food shortage.

7. Brood‐size at eight days has been higher in woodland than in gardens, partly because clutches are larger in woodland and partly because many nestlings die in the garden nests. Proportionately more young die in the nest from large than from small broods.

8. After leaving the nest, the young are fed by the parents for about 20 days. Parents very rarely feed strange young, and do not always feed all their own. Especially the last brood of the season may be strictly divided between the two parents.

9. The garden population has produced an average of 4·1 young per pair per year, and 66% of them have survived to independence. Post‐fledging survival seems to have no relation to weight at the age of eight days. It is probable that at least 62% of young that reach independence survive to the next breeding season. The woodland population has been much less successful on account of heavy predation.

10. The adaptive nature of the breeding season and clutch‐size is discussed.
DISEASE IN A COLONY OF BLACK‐HEADED GULLS LARUS RIDIBUNDUS
Authors: Jennings A. R. , Soulsby E. J. L.
Published: April 2008

An account is given of the disease factors encountered in a colony of Black‐headed Gulls in the breeding season 1956.
A CONTRIBUTION TO THE BIOLOGY OF THE CAPE PROVINCE WHITE‐EYES (ZOSTEROPS)
Authors: Skead C. J. , Ranger G. A.
Published: April 2008

Evidence of the inter‐breeding of grey‐bellied Zosterops (atmorii) and green‐bellied (virens) at King William's Town, C.P. is presented.

In habitat, behaviour, voice, and breeding biology no differences can be found between them.

The roosting and flocking habits are discussed.

Whereas both lay blue eggs, only the green‐belly (virens) has so far been found to lay white eggs.

Incubation periods, ascertained to within a few hours, are mostly between 10 and 11 days.

Details are given of the nestling and post‐nestling periods.

Both insects and fruit are taken and fed to young.

Z. pallida on the Orange River is very similar in habits. There is a noticeable difference in tonal quality of voice but the general patterns of the calls are the same.
THE BIRDS OF THE SANTA ELENA PENINSULA, S.W. ECUADOR
Authors: Marchant S.
Published: April 2008

A systematic account is given of the birds of the Santa Elena peninsula in S.W. Ecuador, based on three years observations (1954‐7) and a collection of 425 skins. The status of individual species is decribed and the different elements of the avifauna discussed, viz. the Equatorial arid fauna, Nearctic migrants, sea‐birds, and other wide‐ranging forms and waterfowl. Seasonal movements of species of the Equatorial arid fauna are indicated in greater detail than has been previously known. The effect of a recently constructed reservoir on the bird life is mentioned. More detailed knowledge of the occurrence of species from the cold Humboldt current is provided. Several additions to the Ecuadorian list are given, and some birds recorded which were hitherto unknown or very rarely recorded from the west coast of S. America. Various matters of taxonomy affecting races of birds along the whole west coast of S. America are discussed.
THE RETURN AND DEPARTURE OF SWIFTS APUS APUS AT OXFORD
Authors: Lack David
Published: April 2008

1. The return in spring and departure in autumn of resident Swifts was studied in six years, primarily by means of a nightly check of roosting birds.

2. The mean date of return in spring has varied by nine days in different years. The return was delayed with a cold northerly airstream, but not otherwise.

3. Soon after its return in spring, a bird sometimes spent a night or two away from the tower.

4. Sometimes in spring, but hardly ever in autumn, a transient Swift spent one night in the tower; occasionally, three adults then roosted together.

5. The number of residents in the tower at the end of May was about 90% of that in the preceding late summer.

6. Members of the same pair usually returned and departed on different days.

7. The mean date at which the adults departed in autumn depends primarily on the date when breeding started, and hence on the weather in May.

8. The parents usually stayed for a few days after their young had left, presumably to put on fat. This interval was longer in those years in which the weather in July had been bad, and in one year it was longer for parents of larger than smaller broods, while it was shorter, irrespective of other conditions, late in the season. Occasionally one, but never both, parents departed before the last of their nestlings, chiefly in fine summers.

9. Adults which laid eggs which failed to hatch tended to leave before the parents of young, but non‐breeding pairs (mainly yearlings) tended to leave later than parent birds that raised young.

10. Autumn departures were held up by depressions, and occasionally by mist.

11. After their mates had departed in autumn, a few individuals “kept company” with other residents, courting and roosting with them.

12. In autumn the birds usually departed from the tower inconspicuously, but twice Oxford residents probably joined a large flock of passing migrants.
BIRD NOTES FROM NORTHERN IRAN
Authors: Passburg Rolf E.
Published: April 2008

Notes are given on the habits and migration of 274 species observed in the course of three years, mainly round Tehran and the southern shores of the Caspian.
THE BREEDING SEASON AND CLUTCH‐SIZE OF THE ROOK CORVUS FRUGILEGUS
Authors: Owen D. F.
Published: April 2008

Annual variations in the breeding season of the Rook near Oxford could be correlated with mean air temperatures in the period prior to egg‐laying.

The most frequent clutch‐size was four to five, and in five out of six years, broods starting as five raised on the average more young than broods starting as four, even though not one brood of five was completely successful. In the other year, broods starting as four and five raised on the average the same number of young per brood.
BIRD OBSERVATORIES
Authors: Cornwallis R. K.
Published: April 2008

An assessment is made of the research being carried out of the British Bird Observatories with suggestions for future work. This is done under three main headings—visual observations, ringing, and critical examination of birds in the hand.
THE COMPOSITION OF GOOSE POPULATIONS
Authors: Boyd Hugh
Published: April 2008

Detailed knowledge of changes in the size and composition of goose populations is of importance in conservation. Long‐term inventories of goose numbers have so far been made only in the United States of America. American and European studies of movement, and of survival, have chiefly depended on the recovery of ringed geese. It has slowly been realised that direct observations of goose flocks can provide much of the information needed to determine the age‐structure of flocks, annual breeding success and mortality. Studies of goose populations employing all the available techniques are now being actively pursued in Britain as well as North America. Some examples are briefly discussed.
BIRD NOTES FROM ADEN AND OMAN
Authors: PAIGE J. P.
Published: April 2008

1. Extensions are given of the recorded range (Meinertzhagen 1954) or periods of occurrence of certain species.

2. Spring passage of waders at Aden was light except for Grey Plover Charadrius squatarola. There was a very noticeable passage of shrikes there 30 April‐12 May.

3. Individuals of many species of northern‐breeding waders were recorded in summer.

4. A light but steady S.W. movement of birds was noticeable at Aden from the beginning of July onwards. Waders began to increase in numbers by the middle of the month, and by the first week in August quite large flocks were present.
OBSERVATIONS ON THE ROOK CORVUS FRUGILEGUS IN SOUTHWEST CORNWALL
Authors: COOMBS C. J. F.
Published: April 2008

Observations on the breeding behaviour of Rooks were made between 1943 and 1955. The gonads of a series of Rooks from the same area and during the same period were examined (Marshall & Coombs 1957). The autumn sexual resurgence is comparable to early spring in both gonad condition and behaviour.

Display postures are described. A slow wing‐raising component, common to several postures, is very rare and perhaps absent when the testes are refractory. It might have a sexual significance.

Rooks use song posts, but song is not used in the establishment or defence of territory.

Copulation occurs most frequently between birds that are not paired to each other. It is usually interfered with, and in more than 90% of the incidents observed the female was incubating. Resemblances between the incubating position and the female soliciting posture may lead to this.

The territory is a small area round each nest: neighbouring territories may overlap. Rooks who are active in pilfering a neighbour's nest for building material, may establish some territorial dominance over it.

Nest sites are selected by both sexes and in both spring and autumn. Either sex can build a nest. Normally the male does most of the stick structure, and the female more of the cup and lining.

During incubation the female is fed on the nest by the male, and after the young have hatched for as long as he can provide food for her as well as the young. Droppings are removed by both parents, partly as a response to fouling of the nest.

Development of the gonads and of the behaviour of juveniles is described. A few birds reach breeding condition at one year old, the majority a year later. Expectation of life at one year old is probably four years.

Some data are given on the relationship with other Corvidae in the area and with some other species.
FURTHER OBSERVATIONS ON MIGRATION IN SOUTHWEST IBERIA
Authors: Henty C. J.
Published: April 2008

Details are given of autumn migration in southwest Iberia, observed at points from Sagres to Tarifa, 24 August‐23 September 1958.

No ‘ rushes ’ of night migrants were encountered and an overall broad front movement probably occurs. Hirundines and raptors passed through daily only at Tarifa.

Migration is discussed in relation to local and general weather conditions.
“NONSENSE” ORIENTATION IN MALLARD ANAS PLATYRHYNCHOS AND ITS RELATION TO EXPERIMENTS ON BIRD NAVIGATION
Authors: Matthews G. V. T.
Published: April 2008

A strong tendency in non‐migratory Mallard to fly N.W. on release is described. This orientation is shown regardless of distance and direction of release, of season or of length of captivity. It is shown at any time of day by birds of both sexes and of all ages, and is unaffected by the topography of the release site. Head winds of moderate strength impart a wider scatter, otherwise winds have little effect. It appears to be a sun‐compass orientation.

The orientation breaks down, probably quite quickly, and is replaced by random wandering. There are no indications of true navigational ability.

It is suggested that the orientation may function to keep flocks together and be related to the northward post‐fledging movements of many birds.

The existence of such a strong orientation and its presence in another non‐migratory bird, the pigeon, is considered to have caused confusion in experiments on navigation undertaken with the latter. Results obtained with pigeons in N. Carolina and Germany can no longer be considered conclusive. The conflict of their results with those obtained in England is resolved.
THE SONGS OF SOME FAMILIES OF THE PASSERIFORMES. I. INTRODUCTION: THE ANALYSIS OF BIRD SONGS AND THEIR EXPRESSION IN GRAPHIC NOTATION
Authors: Thorpe W. H. , Lade B. I.
Published: April 2008

The sound spectrograph, s an indispensable tool for the fuller objective analysis of animal vocalisation. It is particularly valuable in study of bird song. The sound spectrograms themselves, as produced by the instrument, contain, however, an excess of information which is not always relevant to the comparative study of specific songs. Moreover, the scale and delicate shading of the originals render them needlessly difficult for the field student of bird song to interpret, and needlessly expensive for journals to reproduce. A simplified and graphic notation, consisting of a series of conventional symbols, has been worked out. This, it is believed, largely overcomes these difficulties without the loss of any information essential for the field student.
COMPARATIVE BIOLOGY OF THE WHITE BOOBY AND THE BROWN BOOBY SULA SPP. ATASCENSION
Authors: DORWARD D. F.
Published: April 2008

The breeding cycles and related biology of the White Boorby Sula dactylatra and the Brown Booby S. leucogaster at Ascension were investigated between November 1957 and April 1959.

In both species there were marked peaks of laying, with intervening periods of very few new clutches. In the White Booby, although only one full season was studied, an annual cycle was deduced; in the Brown Booby (two full seasons) the cycle appeared to be eight‐monthly. The breeding season (laying of eggs to fledging of chicks) was however roughly the same length in both species, namely six to seven months. Individuals of both species for the most part conformed to the breeding seasons of the population as a whole, i.e. if out of phase for some reason, had a longer or shorter “rest” period as necessary to bring them into phase again for the next season. These discoveries indicate that external factors are controlling the times of breeding. The proximate factors are not known; at Ascension there is no appreciable seasonal variation in day‐length or climate, and possible cycles in the surrounding sea could not be investigated.

The two species' periodicity was such that, if maintained, every two years they would lay at almost the same time of year, July–August. The possible relation of these observations to a single underlying factor, perhaps annual variation in oceanic conditions with their origin in the seasonal melting of the Antarctic ice and consequent effect on the food cycles, is discussed.

Details of incubation, desertion, feeding, care and growth of the chick are given. The regular death of the second chick as a result of asynchronous hatching, and experiments with twins are described. A low breeding‐success, and deaths of chicks from starvation, indicated that both species suffered a shortage of food over an ill‐defined period around August‐September 1958. Regurgitations of food examined throughout the study, and a few observations on feeding, indicated a big overlap in the two species' diets, mainly flying‐fish, but some differences did appear.

Details of moult, mainly in the White Booby, are given. Shedding and re‐growth of the juvenile primaries began at about seven months of age, proceeding from the innermost outwards in three spaced concurrent cycles, this remarkable pattern continuing throughout adult life. A period of pause in the primary moult was correlated with the time when most birds had chicks, but some birds were known to be moulting their primaries while breeding. A prolonged moult with a pause during breeding was indicated by examination of some other Ascension species; the relevance of this to the availability of food and breeding seasons in tropical sea‐birds is discussed.
BEHAVIOUR OF BOOBIES SULA SPP.
Authors: Dorward D. F.
Published: April 2008

Some previously undescribed behaviour patterns, mainly of the White Booby and Brown Booby, were observed in the course of 15 months' general study of the species at Ascension.

The advertisement display of the male was similar to a posture described as a “taking‐off” one in the Gannet, but was clearly used by unmated male White Boobies to attract a mate; in the Brown Booby the same display was performed (and sometimes in flight) by males of established pairs. Two postures, both involving a turning‐away of the prominent facial features and therefore comparable to “Head‐flagging” in gulls, were similar in the two species, but again were seen frequently among unmated White Boobies but established pairs of Brown Boobies. One of these was similar to “Bill‐hiding”, a posture seen in attacked chicks. Others among the twelve behaviour patterns described are food‐begging of the chick (apparently similar to “Head‐wagging”, a movement seen during combats between adult White Boobies, but not Brown), and a remarkable sunbathing posture.

It is suggested that some of the behavioural differences are related to differences in the two species' nesting habits at Ascension.