bluuebunny/crossref_metadata_2025_split huggingface dataset:
The diet of breeding Dippers Cinclus cinclus and their nestlings in the catchment of the River Wye, mid‐Wales: a preliminary study by faecal analysis
Authors: ORMEROD S. J. 
Published: April 2008

A preliminary study by faecal analysis into the diet of seven pairs of breeding Dippers and their nestlings was undertaken in the catchment of the River Wye in spring 1983. Macro‐invertebrate items in faeces could be identified to family and quantified on the basis of mouthparts whilst the macro‐invertebrate prey available to each pair of Dippers was assessed quantitatively by riffle‐sampling.In terms of numerical abundance, ephemeropteran nymphs, particularly Baetidae, and trichopteran larvae, particularly Hydropsychidae, were more important to adults and nestlings, respectively. When prey weights were taken into account, trichopteran larvae were the most important macro‐invertebrate group to both, but especially to nestlings.Some macro‐invertebrate groups were selected in proportion to their abundance in the environment although indices of electivity indicated that prey selection for adults and nestlings, respectively, was negatively and positively correlated with prey weight. Significant changes in diet were also apparent with nestling age: smaller items, such as ephemeropteran nymphs, were eaten by younger nestlings whilst larger items, such as trichopteran larvae, became more frequent up to Day 15 after hatching.
Wing shape variation of Finnish and Central European Willow Warblers Phylloscopus trochilus and Chiffchaffs P. collybita
Authors: TlAINEN JUHA , HANSKI ILPO K. 
Published: April 2008

Wing shape variation of European Willow Warblers Phylloscopus trochilus and Chiffchaffs P. collybita was studied using indices calculated from wing formulae. Our data were from free‐living local populations of P. t. acredula and P. c. abietinus from southern Finland, and P. t. trochilus and P. c. collybita from southwestern Germany.There were no significant shape differences between the subspecies of the Willow Warbler in which sexual dimorphism was pronounced. The subspecies of the Chiffchaff were significantly different while the sexes were not. There were also significant differences between adult and immature individuals in the autumn. The intrapopulation variation must be considered in attempts to recognize different subspecies or populations in data on birds caught during migration.In the Willow Warbler at least, the difference between age‐groups was larger in males than in females. If the change in wing formula due to the complete pre‐nuptial moult is similar in both sexes, juvenile males intermediate between adult females and adult males suffer disproportionately high mortality. It was earlier suggested that sexual selection increases body size in Willow Warbler males, but the present results imply additional selection pressures for increasing sexual dimorphism.
Dominance and anti‐predator behaviour of Great Tits Parus major: a field study
Authors: LAET JENNY F. DE 
Published: April 2008

During the winter of 1981–82 the hierarchical system of free‐living Great Tits Parus major that visited a feeder supplied with sunflower seeds was studied in relation to the appearance of a predator. Without a predator, dominant birds were more successful in feeding and had to wait less before feeding. A significant negative correlation was found between dominance and the sequence of initial arrival.After a Sparrowhawk Accipiter nisus had flown over the feeder, a correlation was found between the birds' dominance and the sequence of their return to the feeder. This field study supports the results of an analogous investigation on anti‐predator behaviour and dominance in captive Blue Tits P. caeruleus.
The breeding of the Wedge‐tailed Eagle Aquila audax in relation to its food supply in arid Western Australia
Authors: RIDPATH M. G. , BROOKER M. G. 
Published: April 2008

The breeding of the Wedge‐tailed Eagle Aquila audax was investigated in four areas of the arid zone of Western Australia from 1968 to 1976, with some supporting data from the adjacent Mediterranean zone. Breeding was dependent on, and geared to, the occurrence of a minimum level of available prey. In the arid zone the seasonally most regular occurrence of the low rainfall, combined with greatest diversity of vegetation and prey, was associated with the most regular breeding and the greatest annual productivity of young per pair. At the other extreme, where an identical mean annual rainfall was distributed more erratically between seasons and years and was combined with a less diverse flora, the prey available to eagles was restricted to virtually one species–the introduced European rabbit Oryctolagus cuniculus. In this situation there were gaps of up to 4 years between the breeding of eagles, because of major fluctuations in the size of the population of its rabbit prey. Their density was actually greatest in those areas where the widely fluctuating food supply occasionally allowed them to breed with considerable success; however, this did not compensate fully for the irregularity of breeding. Where the prey available was thus restricted to a single species and was least stable, the area may have been unable to support a population which could maintain itself without recruitment from outside.Breeding success in the Mediterranean zone was higher than in the arid zone. The Wedge‐tailed Eagle's breeding strategy is conservative (with ’k‐selected‘ characteristics), but this study shows that it is ecologically successful in both zones, although least so where the climate is extremely erratic.
Sensory capacities and the nocturnal habit of owls (Strigiformes)
Authors: MARTIN GRAHAM R. 
Published: April 2008

Behavioural studies show that in the eye of the Tawny Owl Strix aluco both absolute visual sensitivity and maximum spatial resolution at low light levels are close to the theoretical limit dictated principally by the quantal nature of light and the physiological limitations on the structure of vertebrate eyes. However, when the owl's visual sensitivity in relation to naturally occurring ligh levels is analysed, it is concluded that at night there will often be occasions when vision can only be used to control the owl's behaviour with respect to large objects.Owls are capable of detecting and catching prey by hearing alone. However, absolute auditory sensitivity is not superior to that of mammals (including Man), but does appear to have reached the absolute limit on sensitivity in the aerial environment, which is dictated by the minimum ambient sound level.An explanation of the owl's ability to be active at night based only upon high sensory sensitivity is thus untenable. Many features of the natural behaviour of the Tawny Owl (e.g., the high degree of territoriality, prey catching technique, dietary spectrum) may be interpreted as reflections of an additional requirement for the nocturnal habit beyond high sensory sensitivity: detailed knowledge of local topography.
Piping as a display of dominance by wintering Oystercatchers Haematopus ostralegus
Authors: ENS B. J. , GOSS‐CUSTARD J. D. 
Published: April 2008

Although Oystercatchers Haematopus ostralegus wintering in the Exe Estuary performed the piping display in any type of aggressive encounter, it was predominantly observed in two contexts. ‘Solitary piping’ occurred when one individual piped without an obvious opponent being in the immediate vicinity. In ‘piping ceremonies’, two or more individuals piped at each other for prolonged periods at close distance. Prolonged contests over mussels were usually won by the individual that had initially started piping. The most aggressive and successful birds (the dominants), engaged most often in solitary piping and piping ceremonies, using up to 10% of their time this way. This suggests that the behaviour was associated with dominance rank. The hypothesis is that the two birds are likely to start piping if their relative status has not already been established, so that a quick end to a dispute over a mussel or feeding site is not achieved. A dominant individual performs solitary piping from a distance to suppress the aggressive activities of other birds within its feeding range. If this signal fails, the dominant may join the ceremony, explaining why three was the most frequent number of birds involved in piping ceremonies. The ‘butterfly’ flight, used mainly by apparently dominant birds as they arrived on the feeding grounds, may signal their high status to birds already there.The outcome of several piping ceremonies involving birds of known dominance was consistent with this explanation. The location of piping ceremonies involving only two birds (interpreted as piping ceremonies not joined by dominants) at the extremities of the feeding ranges of the most dominant individuals is also consistent with this hypothesis, because this is where their dominance would be expected to decline and would therefore be more likely to be contested. This explanation of piping and butterfly displays assumes that individuals can recognize other individuals or quickly assess their dominance. Since dominant individuals were attacked less often than subdominants and attacking birds were rebuffed less than would be expected if recognition did not occur, we suggest that some form of dominance or individual recognition did exist. The width of the white collar did not correlate with dominance, but the individual variations in this feature may enable birds to distinguish each other and thus learn their relative status. It is intriguing that the diplomatist posture, which is typically used to rebuff misguided attackers, seems almost designed to give the opponent a particularly clear view of the white collar.
Evidence of itinerant breeding of the Red‐billed Quelea Quelea quelea in the Ethiopian Rift Valley
Authors: JAEGER M. M. , BRUGGERS R. L. , JOHNS B. E. , ERICKSON W. A. 
Published: April 2008

This paper provides evidence for itinerant breeding by Red‐billed Quelea Quelea quelea in the Ethiopian Rift Valley. Queleas were mass‐marked with aerially applied fluorescent particles in two separate nesting areas in southwestern Ethiopia during June 1981. Marked adults from both areas were recovered from nesting colonies in the Awash River Valley during August and September, up to 100 days post‐spray and between 500 and 700 km to the north of the spray sites. In the Awash colonies, the presence of marked adults in breeding plumage with interrupted primary wing‐moult, together with two age classes of juveniles, suggests that this was the second nesting. The progress of both the post‐breeding and post‐juvenal primary moults was consistent with an earlier breeding in May and June. The timing of the arrival and departure of birds from these nesting areas also supported the occurrence of double breeding by the same birds. Furthermore, the composition of black facial mask types of adult males was more similar between samples from the southern Ethiopian Rift and Awash Valley than between samples from either of these areas and samples from outside the Rift, providing additional evidence that the same population of birds bred in these two areas of the Rift Valley.Nesting colonies in both areas were scattered in time and space. Colonies in the Awash were distributed for more than 300 km and were established over a two‐month period, which coincided with local differences in the timing of the seeding in grasses. This wide distribution probably increases nesting success in such areas of locally variable rainfall. This contrasts with a stategy of mass migration, where concentrated breeding occurs where and when suitable conditions are first encountered.Knowledge of the location and timing of previously successful nesting areas may increase the success of itinerant breeding, as Queleas seem to use the same areas in successive years if conditions are favourable. Recoveries of marked birds in the Awash were segregated according to both spray site and sex, suggesting some degree of group cohesion by sex from the first to the second nesting. We speculate that post‐nesting group cohesion of adults may provide a means to maintain the integrity of collective group information on seasonal movements. Group cohesion may be facilitated by the high degree of nesting synchrony within colonies.
The vocal systems of two nocturnal burrowing petrels, the White‐chinned Procellaria aequinoctialis and the Grey P. cinerea
Authors: BROOKE M. de L. 
Published: April 2008

I studied the calls of White‐chinned Petrels Procellaria aequinoctialis and Grey Petrels P. cinerea at the Prince Edward Islands in the Southern Ocean. White‐chinned Petrels gave two calls. One, the Wheezy call, was usually given from within breeding burrows, was given in response to playback of strange (= non‐mate) calls, and probably served a burrow defence function. The other call, the Rattle call, was uttered roughly as often on the ground as from within the burrow. This call was mostly given by males and probably served as sexual advertisement. The one identified call type of the Grey Petrel was given in the same circumstances as the Wheezy call of the White‐chinned Petrel.In both species there was evidence of mate recognition of calls. Birds tended to remain silent to the playback of the mate's call, whereas they responded vocally to strange calls.This vocal system, where both sexes share two call types but where sexual dimorphism in call is absent, has not been described before for petrels. Possible reasons for the variation in petrel vocal systems are discussed.
The breeding biology of Guillemots Uria aalge on the Isle of May over a six year period
Authors: HARRIS M. P. , WANLESS S. 
Published: April 2008

The breeding of Guillemots was studied in five areas of different breeding density and habitat type on the Isle of May in 1981‐86. Prior to 1981 numbers were increasing at 5 6° per annum but during the study the rate of increase slowed down and from 1983 to 1986 numbers were fairly constant. Adult survival was high, with a mean minimum annual adult survival of 930% (s.e. = 03). Observations in 1986 suggested that the percentage return of colour‐marked immature birds was low, with only l‐6% and 5.5% of second and third year birds being seen. We suggest that poor recruitment was responsible for the levelling off in numbers at the colony.The timing of laying was constant from year to year in 1981‐85 but was later in 1986. It was significantly and inversely related to sea temperature the previous March. There was a consistent ranking in median laying dates amongst the areas, with area 1 (the highest density of birds) always earliest. However, there was no significant difference in synchrony between the areas. Overall breeding success was high (0–71‐0‐82 young fledged per pair). There was no consistent ranking of breeding success with breeding density, habitat type or laying synchrony.The only aspect of Guillemot biology which changed significantly was the daily food intake of a chick which approximately halved during the study period. However, this reduction in food intake had no detectable effect on either the weight of chicks with wing lengths greater than 60 mm or the amount of time off‐duty breeders spent at the site. Both of these parameters were still consistent with conditions being favourable in 1986.
Unexpected weight gain in resident Antarctic Terns Sterna vittata during the austral winter
Authors: PARMELEE D. F. 
Published: April 2008

Antarctic Terns Sterna oittata (Fig. 1) may display two very different migratory behaviours. According to Cooper (1976), the terns breeding on Tristan da Cunha in the South Atlantic fly thousands of kilometers to the coasts of Africa where they moult. Antarctic Terns that inhabit the more southern and colder Antarctic Peninsula region moult on their breeding grounds. An early account of these seemingly resident peninsular terns (Holdgate 1963) leaves little doubt that at least part of the tern population wintered in the vicinity of Arthur Harbor (64°46′S 64°03′W), Anvers Island, west of the Antarctic Peninsula. Watson (1975) stated that adult Antarctic Terns are generally sedentary around many insular breeding stations, moving only to the nearest open water in winter.During the year 1975 through 1978, 19 tern specimens of different sexes and ages were collected at Arthur Harbor in the non‐breeding season near U.S. Palmer Station. An additional eight terns were collected at a sea short distance from Anvers Island during the non‐breeding season in 1985 (Pietz & Strong, in press). I found that the adult birds taken at the height of winter weighed significantly more than the 150‐180g of a normal breeding Antarctic Tern. This unexpected discovery prompted me to examine the weights of an additional 34 specimens that had been collected at or near Anvers Island during several breeding seasons. By comparing the weights of adult terns by sex, age, and collection date (Fig. 2, Table 1) I found that both males and females weighed significantly more in the winter non‐breeding season (April‐September) than in the summer breeding season (October‐March) (t24= 6.57, P < 0.001, and t16= 5.71, P < 0.001, respectively). No significant differences were detected between male and female weights in summer(t23=0.76, P >0.20) or winter (t17=1.16, P0.20). In short, it appears that body‐weights of adult terns rise rather dramatically following breeding, attain a peak in mid‐winter, and then fall at the approach of the next breeding season (Fig. 2). I suggest that this increased body‐weight is an adaptation to the austral winter rather than simply a recovery from weight loss due to energetic costs of breeding and moulting.
Distribution and behaviour of passerines around Peregrine Falco peregrinus eyries in western Greenland
Authors: MEESE ROBERT J. , FULLER MARK R. 
Published: April 2008

This paper describes the distribution and behaviour of passerine birds within 1 km of Peregrine FalconFalco peregrinuseyries in western Greenland. Passerine populations were censused in 1983 around six cliffs occupied by nesting Peregrines and at six sites on the open tundra, and in 1984 at two unoccupied sites suitable for Peregrine nesting.Four passerine species accounted for over 90% of birds seen. Within 400 m of Peregrine occupied cliffs, three species, Lapland LongspurCalcarius lapponicus. Northern WheatearOenanthe oenanthe, and Common RedpollCarduelisflammea, were found in lower than average abundance while the fourth, Snow BuntingPlectrophenax nivalis, was found in increased abundance. Our indirect tests suggest that Peregrine presence, rather than direct predation, was responsible for the distributions of the first three species. The Snow Bunting, however, behaviourally adapts to Peregrine presence in order to exploit nesting habitat available at the cliff base.These results contrast strongly with those reported by other Arctic workers, where increased abundances of potential prey were observed in close proximity to nesting Peregrines.
Weight loss of the female during the first brood as a factor influencing second brood initiation in Great Tits Parus major and Blue Tits P. caeruleus
Authors: LAET JENNY F. DE , DHONDT ANDRÉ A. 
Published: April 2008

We tested the hypothesis that the weight lost by female Great and Blue Tits Parus major and P. caeruleus while raising their first brood influences their ability to start a second brood. The evening weight of female parents was recorded when the nestlings were 5 and 13 days old, in different years and habitats. Several predictions were tested: (1) both species lose weight while raising nestlings and Great Tit females which start a second brood lose less weight than females which do not; (2) differences in the average weight lost between years and areas correlate with differences in the proportion of second broods; (3) the relative weight loss in Blue Tits, which only rarely undertake second broods, is higher than in Great Tits in which second broods are more common. Other factors also are related to the probability of undertaking a second brood: more second broods are undertaken by more successful females, adult females and females that lay earlier.The comparison of Great and Blue Tits suggests that the two species use different reproductive strategies.
Integrated population monitoring of breeding birds in Britain and Ireland
Authors: BAILLIE STEPHEN R. 
Published: April 2008

Effective wildlife monitoring schemes identify changes in population variables that require conservation action. This must be based on an understanding of normal patterns of population variability. Monitoring schemes ideally provide data on the stages of the life cycle at which changes are taking place and indications of the probable causes of change.The Integrated Population Monitoring Programme of the British Trust for Ornithology aims to fulfil these requirements for British birds. It encompasses existing BTO projects that measure population size, productivity and survival rates, principally the Common Birds Census, Waterways Bird Survey, Nest Record Scheme, Constant Effort (mist‐netting) Sites Scheme and the Ringing Scheme. Integrated analyses of long‐term BTO data are being used to study the population dynamics of individual species. Relationships established through such analyses will be used to construct models that will predict population performance, and against which observed performance can be compared.A simple application of Integrated Population Monitoring is presented using data for the Song Thrush (Turdus philomelos), a species which has been declining throughout most of Britain since the mid 1970s. No reduction in reproductive performance was detected and the decline appears to have been brought about through reduced survival rates. Factors responsible for much of this decline were identified from a multiple regression model involving winter weather conditions.
The damage‐conservation interface illustrated by geese
Authors: OWEN MYRFYN 
Published: April 2008

Changes in legislation, in public attitudes and in shooting practices, both in Britain and overseas, have allowed populations of geese which winter in Britain to increase in numbers. Since 1960 the number of individuals in the seven populations that come into conflict with agriculture has increased almost fivefold.There are serious conflicts between geese and farmers in some localities, where damage is alleged to growing grass, cereals and high value cash crops. Despite extensive studies over 20 years, it has proved impossible to devise precise and cost‐effective methods of assessing the damage caused by geese and to provide a fair and workable system of compensationFarmers and their representatives are calling for a co‐ordinated cull to reduce population sizes substantially. There are, however, a number of political and practical problems in undertaking population control, except perhaps in the feral populations of GreylagAnser anserand Canada GeeseBranta canadensisin England.Proposals are put forward for each species, which take into account the international responsibility of each country to safeguard the populations of migratory birds, and which provide solutions to the local serious problems of farmers. These proposals involve the setting aside of land for geese, either by the creation and management of reserve areas or by making payments to farmers to tolerate the birds on their land.