Behavioural effects of hyperstriatal ablation in Gallus domesticus

Hens with bilateral ablations in the hyperstriatal complex were compared with birds with bilateral ablations in the posterior telencephalon and sham-operated controls with regard to their behaviour in their home pens, exploratory behavior and their responses to (1) a simulated aerial predator, (2) a startling stimulus and (3) an auditory stimulus. Ablations involving the ventral hyperstriatum made the birds less reactive to frightening stimuli while ablations in the posterior telencephalon resulted in the bird “freezing” in the experimental situations.     

Behavioural responses to visual stimuli following posterior dorsal telencephalic ablations in Gallus domesticus

The behaviour of chickens following posterior dorsal telencephalic ablations was studied in response to humans, strange hens, aerial predators, ground predators and a visual startle stimulus. The ablations had no effect on the birds' response to either the aerial or ground predator but there was a significant reduction in pacing after the visual startle stimulus. Following posterior telencephalic ablation the birds showed significantly fewer attacks and threats in encounters with unfamiliar hens but showed exaggerated escape/avoidance behaviour to humans in both their home pens and in experimental testing cages. The reasons for this avoidance behaviour to humans are discussed but no definite conclusions could be drawn.     

Influence of nest seclusion and nesting material on pre-laying behaviour of laying hens

Provision of nest sites is beneficial for the welfare of laying hens in intensive production systems. The design of these nest sites has a direct effect on pre-laying behaviour. The aim of this study was to investigate the effects of screening off the entrances of the nest boxes with non-transparent flaps and providing nesting or flooring material on pre-laying behaviour. Eighteen individual Hisex brown laying hens and 18 groups of five hens were tested for 2 days in a test cage containing three nest boxes each with a different nesting material (peat, artificial turf and plastic-coated wire mesh). On one of the days the nest boxes were equipped with plastic flaps at the entrances. Pre-laying behaviour was analysed using focal sampling. Both degree of seclusion and nesting material had an effect on pre-laying behaviour of hens. Nest boxes with flaps were visited less frequently but for a longer duration per visit than nest boxes without flaps. Hens spent more time sitting and scratching, and less time standing and moving when flaps were present. Hens also received fewer pecks (group test) when nest boxes were equipped with flaps. Major differences were found between pre-laying behaviour on coated wire mesh compared to peat and artificial turf with shorter duration of nest visits (group test), more standing (group test) and moving (individual and group test), and less sitting (individual and group test) and object pecking (group test) on coated wire mesh. Differences in pre-laying behaviour on peat versus artificial turf were observed for the behaviours moving (less on peat), sitting (more on peat in the individual test) and object pecking (more on peat in the group test).

It is concluded that hens show more settled pre-laying behaviour and more nest-building behaviour in the presence of flaps at the entrances of nest boxes. These results indicate that seclusion of nest boxes with non-transparent flaps is beneficial to laying hen welfare. Differences in pre-laying behaviour also suggest that plastic-coated wire mesh is less suitable as nesting material than peat and artificial turf.     

Body condition, territory ownership and age-related reproductive performance in Spruce Grouse Dendragapus canadensis hens

Adult Spruce Grouse Dendragapus canadensis hens show better reproductive performance (i.e. larger clutch size, earlier clutch initiation, higher frequency of renesting) than year-lings. Body and breast muscle weights, condition indices and relative body composition were compared between adult and yearling birds from northeastern Ontario, Canada, to determine whether differences in endogenous reserves mobilized for egg production and (or) territory ownership could explain these differences in reproductive performance. Adults and yearlings showed similar declines in body-weight, breast muscle weight and condition indices from the pre-laying to the post-laying period, but no significant interage differences emerged at any stage of the breeding season. Changes in body composition, especially gut structure, were similar in all birds; this result is consistent with a dietary shift in both age classes from a fibrous winter diet to more succulent foods in spring. Non-territory-holding (replacement) yearlings also had similar body-weights and breast muscle weights and were in similar condition to territory holders (residents) in the pre-laying period. My findings do not support the hypothesis that differences in body condition and territory occupancy can account for differences in age-related reproductive performance in Spruce Grouse.     

Establishing body-size indicators in a study of female spruce grouse Dendragapus canadensis

Seven measurements were taken from 72 adult and yearling spruce grouse Dendragapus canadensis hens collected over a 10-year period from north-eastern Ontario, Canada. A principal components analysis (PCA) indicated keel ridge length, keel total length, and femur length, these being the most representative measurements of general body size. Skeletal mass, caecal length, wing length, and foot length had lower character loadings on the first principal component axis (PC1), suggesting they are unreliable measurements of body size. Measurements taken from bones (i.e. keel, femur) were more representative of general body size than external morphometric measurements (e.g. wing and foot length) which ornithologists traditionally use to estimate body size. Pre-laying adults were the smallest individuals and pre-laying yearlings the largest in the population studied. A discriminant functions analysis (DFA) of the seven measurements, with separated body mass as an eighth variable, demonstrated distinct separation between pre-laying and post-laying groups of birds on the basis of separated body mass. Keel ridge length was further implicated as an effective variable in the discrimination of birds from different laying groups.     

The interaction of testosterone and breeding phase on the reproductive behavior and use of space of male zebra finches

It is well known that androgens play a critical role in mediating the reproductive behavior of males. However, many laboratory experiments that examined the effects of testosterone in male songbirds typically limited their investigations to the early phase of breeding. We sought to determine the influence of testosterone on social behavior, pair bonding, nesting, and use of space in captive zebra finch (Taeniopygia guttata) males as a function of breeding stage (pre-laying, incubation, and nestling phases). Fourteen males were released into an aviary with 14 females and allowed to breed for 7 weeks. Half of the males were given testosterone implants and half were given control implants. During the pre-laying phase, testosterone-implanted males spent significantly more time in nesting activities than control birds and more time elapsed from starting to build a nest to when their mates initiated egg-laying. During the incubation phase, testosterone-implanted subjects spent significantly more time in female-directed and undirected singing. Use of space varied between hormone conditions depending upon breeding phase: there was no difference during pre-laying, but during the incubation and nestling phases, testosterone-implanted subjects used significantly more space. This significant increase in "home range" during the latter phase of the breeding cycle coincides with results from field studies on other species. These results underscore the importance of considering breeding phase in assessing the behavioral sensitivity to hormones.     

Copulation behaviour and paternity in shy albatrosses (Thalassarche cauta)

We investigated the mating system of shy albatrosses Thalassarche cauta by combining behavioural observations during the pre-laying period with genetic paternity analysis. Genetic data on the mating systems of several procellariiform seabirds have recently become available, but data on the reproductive behaviour of these species are rarely obtained. Our main aims were to describe the copulatory behaviour of this species and identify how males achieve within-pair and extra-pair paternity (EPP). Most copulations occurred on the nest, were unforced and were within-pair. Females controlled the success of copulations and were observed soliciting extra-pair matings. Within-pair and extra-pair copulations were behaviourally similar. A low frequency (7–10%, n =29 chicks) of EPP was detected despite male use of frequent copulation as a paternity guard. The pre-laying foraging exodus of female shy albatrosses differed from that in other albatrosses: it was relatively short in length, lasting c . 2 days, and within-pair copulations occurred after the female's return 2 days before laying. This may reflect the close proximity of feeding grounds to the breeding colony.     

Mounting frequency and number of cloacal contacts increase with age in common terns Sterna hirundo

We investigated courtship feeding and copulatory behaviour of common terns Sterna hirundo in relation to age. We found a significant positive correlation between the number of courtship feedings delivered to females and the number of mountings. Moreover, both courtship feeding and mounting rates were positively correlated with female and male age. Also, the number of cloacal contacts per mounting increased significantly with male or female age, which may indicate an increase in copulatory ability with age. The number of mountings for older birds was up to three times that for younger birds. Presuming that transfer of sperm is proportional to the number of cloacal contacts, older birds may have transferred up to six times more sperm than younger birds during the pre-laying and laying period. These results may account for the preference of young females for older mates as well as for older extra-pair mates.     

Geolocators reveal migration and pre-breeding behaviour of the critically endangered Balearic Shearwater Puffinus mauretanicus

Using combined miniature archival light and salt-water immersion loggers, we characterise the year-round individual at-sea movements of Europe's only critically endangered seabird, the Balearic shearwater Puffinus mauretanicus, for the first time. Focusing on the non-breeding period, we show that all of the 26 breeding birds tracked from their breeding site on Mallorca in the Mediterranean Sea successfully made a 2-4 month migration into the Atlantic Ocean, where they utilised well-defined core areas off Portuguese and French coasts. As well as identifying high-risk areas in the Atlantic, our results confirm that breeding birds spend most of the year concentrated around productive waters of the Iberian shelf in the western Mediterranean. Migration phenology appeared largely unrelated to the subsequent (distinctly synchronous) breeding attempt, suggesting that any carry-over effects were compensated for during a long pre-laying period spent over winter in the Mediterranean. Using the light and salt-water immersion data alone we were also able to characterise the pattern of pre-laying visits to the colony in considerable detail, demonstrating that breeding pairs appear to coordinate their over-day visits using a high frequency of night-time visits throughout the winter. Our study shows that geolocation technology is a valuable tool for assessing the spatial distribution of risks to this critically endangered species, and also provides a low-impact method for remotely observing the detailed behaviour of seabird species that may be sensitive to disturbance from traditional study methods.     

Female aggression and the maintenance of monogamy: female behaviour predicts male mating status in European starlings

Any reduction in the fitness of a breeding female induced by the settlement of additional females with her mate creates a conflict between the sexes over mating system. In birds, females are often aggressive towards other females but few studies have been able to quantify the importance of female-female aggression for the maintenance of monogamy. This study of the European starling, Sturnus vulgaris, quantifies male and female behaviour towards a potential prospecting female, presented in a cage during the pre-laying period, and relates it to the subsequent mating status of the male. A solitary breeding male was given the opportunity to attract an additional mate, which almost half of the males did. No biometric characters of the male or female were related to the subsequent mating status. Males demonstrated mate-attraction behaviour towards the caged female but the behaviour of the male did not predict the likelihood to attract an additional female. However, the proportion of time that the female spent near the potential settler was related to mating status, indicating that females that reacted more strongly towards a potential female competitor maintained their monogamous status. These results suggest that female behaviour may play an important role in shaping the mating system of facultatively polygynous species.     

BREEDING BIOLOGY OF THE BEARDED VULTURE IN SOUTHERN AFRICA,PART I: THE PRELAYING AND INCUBATION PERIODS

Brown, C. J. 1990. Breeding biolo of the Bearded Vulture in southern Africa, Part I: The pre-laying and incubation periods. Ostrich 61: 24–32.

In southern Africa the Bearded Vulture Gpaetus barbatus lays its eggs in mid-winter. between the second half of May and the first week of July. Pairs became more active in their nesting areas about six weeks before laying and usually roosted there at night. Courtship flights were less frequent and demonstrative than in Eurasian birds and took place mainly in the late afternoons. During the pre-laying period most nest visits (77%) were to bring nesting material, 92% by the male. All nesting material was arranged by the female. Copulation was always preceded by allopreening, and occurred most frequently in the mornings. No copulation or courtship display took place after the first egg had been laid. Of 18 clutches, 16 (89%) contained two eggs and the remainder one egg. The laying interval was usually 3–5 days (range 2–9 days). Incubation started with the first egg and was evenly shared by both parents during the day, but only the female incubated at night, individual pairs maintained distinctive nest attendance and foraging period timetables, which allowed sufficient time for self-foraging by both parentes. No food was brought into the nest during the pre-laying and incubation periods, but in some pairs food was cached in nearby potholes in cliffs. The incubation period was 56–57 days.     

Evaluating the Impact of Handling and Logger Attachment on Foraging Parameters and Physiology in Southern Rockhopper Penguins

Logger technology has revolutionised our knowledge of the behaviour and physiology of free-living animals but handling and logger attachments may have negative effects on the behaviour of the animals and their welfare. We studied southern rockhopper penguin (Eudyptes chrysocome) females during the guard stage in three consecutive breeding seasons (2008/09−2010/11) to evaluate the effects of handling and logger attachment on foraging trip duration, dive behaviour and physiological parameters. Smaller dive loggers (TDRs) were used in 2010/11 for comparison to larger GPS data loggers used in all three seasons and we included two categories of control birds: handled controls and PIT control birds that were previously marked with passive integrative transponders (PITs), but which had not been handled during this study. Increased foraging trip duration was only observed in GPS birds during 2010/11, the breeding season in which we also found GPS birds foraging further away from the colony and travelling longer distances. Compared to previous breeding seasons, 2010/11 may have been a period with less favourable environmental conditions, which would enhance the impact of logger attachments. A comparison between GPS and TDR birds showed a significant difference in dive depth frequencies with birds carrying larger GPS data loggers diving shallower. Mean and maximum dive depths were similar between GPS and TDR birds. We measured little impact of logger attachments on physiological parameters (corticosterone, protein, triglyceride levels and leucocyte counts). Overall, handling and short-term logger attachments (1–3 days) showed limited impact on the behaviour and physiology of the birds but care must be taken with the size of data loggers on diving seabirds. Increased drag may alter their diving behaviour substantially, thus constraining them in their ability to catch prey. Results obtained in this study indicate that data recorded may also not represent their normal dive behaviour.     

THE BREEDING OF CORY'S SHEARWATER CALONECTRIS DIOMEDEA ON THE SALVAGE ISLANDS

The breeding of Cory's Shearwater on Selvagem Grande was studied during the seasons of 1968 and 1969, on a number of specially timed visits. After a pre-laying exodus (duration not determined) the birds returned in a mass to the island on 26 May 1969 and laying began immediately reaching its peak on 31 May. Egg dimensions and weights are tabulated. In most cases the female handed over to the male immediately after laying, and the two sexes incubated in alternating spells averaging about six days. The incubation period averaged 53-8 days. The chicks reached their maximum weight at about 53 days, but the fledging period was not determined. In 1968 young birds were leaving the nest on 22–25 October, about 90 days after the 1969 mean hatching date. Herring Gulls were important egg predators, but losses of chicks were few, 29 out of a sample of 30 being alive at the age of about 60 days.     

Hippocampal ablated homing pigeons show a persistent impairment in the time taken to return home

Summary Homing pigeons were subjected to either hippocampal or control anterior forebrain ablations to examine what role the hippocampus and related structures may play in homing behavior. One year after surgery, the test birds were released from five locations where they had never been before. Both groups were successful in orienting homeward from the release sites, indicating that the hippocampus is not necessary for the neural regulation of a pigeon's map and compass system. Nonetheless, hippocampal ablated pigeons were significantly poorer with respect to the time required to return home, indicating a homing performance impairment. Alternative hypotheses are discussed to explain this result, the most parsimonious being impaired ability on the part of the hippocampal ablated birds to direct a course homeward.     

On the feeding and social behaviour of the laying hen

This paper describes a study of the influences of early husbandry conditions, social attraction and social rank on various aspects of the feeding behaviour of laying hens.Birds were raised in flocks of 10, 60 or 500. Groups of 3 birds, selected from flocks of the same size, were then housed in pens. Some groups consisted of hens raised in the same flock, and some of birds raised in different flocks. The feeding and agonistic behaviour of each group at each of 5 types of feeder was observed and compared with the behaviour shown when the birds had free access to a 1-m long food trough. Each of the 5 feeders offered the same area of feeding space, but differed in its partitioning and spatial distribution. One feeder had a single unpartitioned feeding space. The other 4 feeders had 3 partioned feeding spaces which were adjacent, or separated by distances of 10, 20 or 40 cm, respectively.For the 5 feeders, total feeding times and lengths of feeding bouts were greatest, and the number of feeding bouts least, when the feeding space was unpartitioned. Synchrony of feeding behaviour was low when the feeding space was unpartitioned or the partitioned spaces adjacent, but was comparable to that at the 1-m long food trough when the distance between partitioned feeding spaces was 10 cm or greater. When feeding space was partitioned, the likelihood that 2 birds would eat together at the same site increased with the distance between feeding space. Dominant birds always exhibited the longest feeding bouts and greatest total feeding times, but were less likely to feed in the same space as another bird, and exhibited less synchrony of feeding behaviour than subordinates. The size of the flock in which the birds were raised, and whether or not the birds in a group had been raised together or apart, had no clear effect on behaviour.These results indicate that, within the limits of this experiment, early husbandry conditions do not influence behaviour shown during feeding in later life, and that social attraction has a greater influence on the feeding behaviour of hens than is generally assumed. In view of this latter finding, it is postulated that in attempting to determine the requirements of laying hens for feeding space, attention must be paid to social attraction as well as to competition at the feeder.     

Aggressive behaviour in Montagu’s harrier Circus pygargus during the courtship period

Aggressive behaviour of Montagu’s harrier was observed during the pre-laying period in the 1992–1995 seasons on the calcareous marshes of Chelm in Eastern Poland. In total, 435 flights performed by 24 pairs of individually marked harriers were analysed. All flights were performed in relation to the territory of defence. Males performed 61% of aggressive interactions while females performed 39%. Intraspecific and interspecific aggression comprising direct attacks (58%), escorts (13%), pursuits (28%) and “mirror behaviour” (1%) were described for the first time. Interspecific aggressive behaviour occurred only near territory boundaries. The main intruders were marsh harriers Circus aeruginosus breeding on the same marshes. Occasionally, harriers attacked curlews Numenius arquata, short-eared owls Asio flammeus, magpies Pica pica, hooded crows Corvus corone cornix, common buzzards Buteo buteo or hobbies Falco subbuteo. Four cases of communal mobbing were observed. Three to five males from the neighbourhood attacked the intruders together. Intraspecific aggressive behaviour was observed in the pair territory, near the boundary or at a distance of up to 100 m from the defended area. Aggressive interactions performed by both sexes were more frequent towards birds of the same sex. Females defended their territories more aggressively against females. Similarly, males were more aggressive against males. All cases of aggressive behaviour were observed near harrier territories. Aggressive relations between birds outside breeding territories or when foraging around marshes were not observed.     

The breeding biology and population dynamics of King Penguins Aptenodytes patagonica on the Crozet Islands

Among King Penguins Aptenodytes patagonica at Possession Island, one of the Crozet Islands, the length of the moult period, pre-laying period, incubating and brooding shifts were highly variable according to the year and to the stage of the breeding season. The moulting period was shorter in late breeders than in early breeders. Only half of the birds which successfully reared a chick bred the following cycle, but late in the season. Almost all these late breeders were unsuccessful. The reasons for the high variability in the breeding pattern observed in this species between years, as well as between colonies and between individuals are discussed. Breeding success was on average 30.6% and survival during the first year at sea could reach 50%. The survival of adult birds has increased during the past 10 years from 90.7% to 95.2% per annum. Despite an almost biennial breeding frequency and a very high rate of chick loss during the winter fast, the King Penguin population of Possession Island has doubled between 1966 and 1985 due to a high survival rate of adult and immature birds. The increase during the last decade in adult survival and in adult and chick condition suggests that the population increase could be the result of an improvement in food availability.     

ABNORMAL MIGRATION AND HYBRIDIZATION OF LARUS ARGENTATUS AND L. FUSCUS AFTER INTERSPECIES FOSTERING EXPERIMENTS

Between 1962 and 1966 eggs of Larus argentatus and L. fuscus were interchanged andalmost 900 young were reared by the wrong species. Many of these cross-fostered young were later recovered or retrapped on and away from the colonies.
The British population of argentatus is sedentary and ringed birds are not recovered outside Britain, whereas fuscus normally migrates. Many cross-fostered argentatus migrated to France, Spain and Portugal, areas where fuscus is common, but they did not migrate as far as the control fuscus . It is possible that these cross-fostered argentatus had followed their foster parents when these migrated, but this is unlikely as the cross-fostered fuscus also migrated although their foster parents would have remained in Britain.
Despite wide ecological and behavioural overlaps, interbreeding between L. argentatus and L.fuscus is exceedingly rare. However, as a result of cross-fostering experiments, 31 and 40 mixed pairs were found on Skokholm in 1968 and 1969 respectively. Although some of the birds involved were unringed it is probable that all the adults in mixed pairs had been cross-fostered. Other cross-fostered birds were found mated with their own species and it appears that the sex of the imprinted birds was important. Female gulls will usually only mate with males of their own species, or in the case of the cross-fostered birds, with males of their foster species. Males will mate with either species.
Evidence is given that suggests that the colour of the mantle and wings is important in species recognition at long range, and the colour of eye-ring and join of the mandibles for recognition at short range. The role of voice is uncertain but general behaviour is probably unimportant.     

Ravens, Corvus corax, differentiate between knowledgeable and ignorant competitors

Human social behaviour is influenced by attributing mental states to others. It is debated whether and to what extent such skills might occur in non-human animals. We here test for the possibility of ravens attributing knowledge about the location of food to potential competitors. In our experiments, we capitalize on the mutually antagonistic interactions that occur in these birds between those individuals that store food versus those that try to pilfer these caches. Since ravens' pilfer success depends on memory of observed caches, we manipulated the view of birds at caching, thereby designing competitors who were either knowledgeable or ignorant of cache location and then tested the responses of both storers and pilferers to those competitors at recovery. We show that ravens modify their cache protection and pilfer tactics not simply in response to the immediate behaviour of competitors, but also in relation to whether or not they previously had the opportunity of observing caching. Our results suggest that the birds not only recall whom they had seen during caching, but also know that obstacles can obstruct the view of others and that this affects pilfering.     

To breed or not to breed: endocrine response to mercury contamination by an Arctic seabird

Mercury, a ubiquitous toxic element, is known to alter expression of sex steroids and to impair reproduction across vertebrates but the mechanisms underlying these effects are not clearly identified. We examined whether contamination by mercury predicts the probability to skip reproduction in black-legged kittiwakes (Rissa tridactyla) from Svalbard. We also manipulated the endocrine system to investigate the mechanism underlying this relationship. During the pre-laying period, we injected exogenous GnRH (gonadotropin-releasing hormone) to test the ability of the pituitary to release luteinizing hormone (LH, a key hormone for the release of sex steroids and hence breeding) in relation to mercury burden. Birds that skipped reproduction had significantly higher mercury concentration in blood than breeders. Endocrine profiles of these birds also varied based on breeding status (breeders versus non-breeders), mercury contamination and sex. Specifically, in skippers (birds that did not breed), baseline LH decreased with increasing mercury concentration in males, whereas it increased in females. GnRH-induced LH levels increased with increasing mercury concentration in both sexes. These results suggest that mercury contamination may disrupt GnRH input to the pituitary. Thus, high mercury concentration could affect the ability of long-lived birds to modulate their reproductive effort (skipping or breeding) according to ongoing environmental changes in the Arctic, thereby impacting population dynamics.