Our knowledge of the Red-breasted goose population has improved considerably over the last 12 years with work carried out in both the breeding and wintering areas. The Romanian and Bulgarian Dobrogea is the main wintering area of the Red-breasted goose. The population size varied considerable during the study period (October 1998 - March 2001) in the wintering area from 41,195 to 88,425. The weather conditions had a strong influence on the number of the geese wintering in the Dobrogea and within the wintering area, the climate conditions influenced their distribution in most years. Geese were spread across the Dobrogea in both inland and coast regions until December. During the coldest period of the winter, in January, the whole population of Red-breasted goose was concentrated on a few lakes located on the Black Sea coast. Some of these major roost sites are protected as reserves. Most frequently, the Red-breasted geese were seen in the Dobrogea in mixed flocks with the White-fronted geese. The geese feed exclusively on crops, mainly on winter wheat but also on barley. In the late autumn in October and November, they preferred newly sown fields where they fed on seeds of winter wheat left on the surface. Later during the winter, the leaves of winter wheat and barley remained the only food available. Geese preferred to feed closer to the roost from December to February but in January, they showed a preference for fields facing east and south. Other landscape variables such as distance to the roads, distance to the villages and slope, were less important. The carrying capacity of the area was calculated and showed that the area cultivated can presently support a larger number of geese. Geese grazing caused losses of yield of on winter wheat causing economic consequences for the farmers. After privatisation, the attitude of farmers towards geese changed. Some guarded their crops, hunted geese or occasionally used poison against geese. Poison was also used more frequently against illegal sheep grazing. This practice is a major concern and affected a number of species. Hunting and farming were the main causes of disturbance during the winter. In Dobrogea, farming activity decreased from November to January. The hunting pressure was constant during the winter and larger at the weekend compared to working days.

This study was undertaken to investigate reports of periodic large fluctuations in the Gannet Sula bassana (L) population on Ailsa Craig between 1936 and 1976. Also, aspects of the breeding ecology and behaviour of a west coast gannetry (Ailsa) were to be compared with data collected by Nelson (1965, 1966c) from the Bass Rock on the east coast. Regular photographic counts were made between September 1974 and April 1977. The number of occupied sites was counted directly from the photographs. Sample counts of breeding pairs and non-breeding nest or site holders were made from the ltind, and the ratio used to correct each, section to give separate totals of breeders and non-breeders. Counts are thought to be accurate to within 7 per cent of the mean. In 1975 and 1976 colony occupation followed an approximately normal distribution, with a gradual spring build-up, a summer peak and a decline during late September and early October. Breeding pairs made up about 80 per cent of the mean mid-April/early May totals. During May and early June there was a 20 per cent increase in the number of occupied sites, so that proportions of sites held by breeders and non-breeders during the summer were about 60 per cent and 40 per cent respectively. A few birds were present in the club areas in April. Numbers remained low until June when there was a rapid increase. Maximum numbers were 245 birds in 1975 and 707 in 1976. Numbers declined during August and early September. Although the seasonal patterns of occupation were similar in 1975 and 1976 counts in the latter were consistently higher, particularly early in the season. The breeding population increased by 6 per cent from 9670 pairs to 10200 pairs, and the maximum number of occupied sites increased from 14880 to 16220, an 11 per cent increase. The latter was largely made up of non-breeding site holders. Between June and September the number of occupied sites showed considerable variation (up to 17 per cent over a 10 day period). In 1975 and 1976 the difference between the mid-April count and the summer maximum was about 30 per cent. Thus isolated counts made at different times of the season could lead to the conclusion that the population shows massive annual fluctuations. The number of chicks fledging in 1975 and 1976 were estimated at 6740 and 7110 respectively. Comparison of the totals obtained in this study using photographs and Gibson's comparable direct counts showed good agreement when the former were corrected to give occupied nests. Fluctuations in annual counts can largely be explained in terms of counting error and seasonal variations in the number of non-breeding birds present in the colony. Differences in population dynamics of west and east coast gannetries are discussed in detail, with particular reference to colony interchange amongst the former.

The behaviour, ecology and energetics of the East Canadian High Arctic light-bellied brent goose (Bronto bernicla hrota) was investigated to determine winter feeding Site selection on Strangford Lough, Co Down, Northern Ireland. The seasonal use of mudflats, saltmarsh and improved pasture was assessed to evaluate the role these habitats play in fulfilling the energy requirements of the geese throughout the wintering period. Brent geese began feeding on eelgrasses Zostera spp. on arrival in late August early September. Single adults arrived first and were in poorer physical condition than paired or family adults which arrived later. Differences in distribution of feeding and physical condition suggests that families are more able than paired or single birds to maintain access to a better quality/quantity food supply over the winter. The activity budget and net energy results highlight the importance of Zostera spp. and the energetic constraints faced by brent geese feeding on Zostera spp. over winter. Position-sensitive radio telemetry provided an accurate and effective method for determining the time spent feeding by individual brent geese throughout the 24hour period in late winter early spring. At this time brent geese rely heavily on the contribution from improved pasture in order to meet their daily net energy . requirement prior to spring migration. Brent geese engaged in night time feeding, exclusively on the mudflats. Night-time feeding occurred from October to April, peaking in mid-winter. This activity appears to be a strategy for the geese to meet their energy requirements during shorter, colder winter days. Feeding on saltmarsh vegetation occurs subsequent to the depletion of Zostera spp. and at a critical time in mid winter and is constrained by the availability and quality, rather than quantity, of the food resource. The study's findings would suggest that for the future conservation of the geese the main conservation requirements for the population is the maintenance of intertidal habitat quality together with the creation of inland refuaes in areas where there may be conflict with agricultural interests.

The thesis provides a description of activities in captive Gadwall, emphasising male epigamic display movements and calls. Analysis was based upon film, video-and audio-tape recordings. Quantitative measures were obtained for the spatial and temporal relations between mates and between members of different age and rearing groups within a flock of 10 to 15 free-ranging, wing-clipped birds. Spatial relations and the activities of each individual were recorded every five minutes on 40 days during nearly two years, and the data were subjected to computer analysis. A relatively close relationship was not only found between mates, but also between any birds of the same group. At different times of the year, different patterns of organisation prevailed. Proximity and synchrony of activities in mates were most frequent during the months preceding the breeding season and infrequent during the breeding season. This held for all pairs, including those in which the female failed to lay eggs, suggesting an inherent tendency for the pair bonds to dissolve in summer. Testosterone was injected into 18 subadult, and 8 adult males in eclipse plumage in order to investigate whether this hormone promotes male epigamic and aggressive behaviour in Gadwall as it has been reported to do in some other duck species. The frequencies of communal courtship and pre-copulatory displays, and in some cases of aggressive actions increased dramatically in the experimental birds, but not in the controls. Thus the testosterone injected birds showed significantly higher frequencies of the recorded activities. Response varied strongly between different males and different tests. It is suggested that this variability is---at least partly---due to the birds influencing each other's behaviour. Temporal aspects of the experiments such as response latency and long-term effects of the treatment are discussed. The injected testosterone advanced voice breaking in the subadult drakes.

No description available.

This thesis examines breeding season timing and seasonal declines in reproductive success in piscivores nesting inland near the equator. Also explored are the effects of sexual character intensity and nest-site characteristics on breeding timing, fecundity and mate choice, as well as the effects of resource partitioning between two similar piscivores. P. carbo lucidus is a relatively common, but little-studied, piscivore of sub-Saharan Africa. Lake Naivasha (0° 46' S) is reputed to be seasonally-constant in fish production. The colony studied was newly-established in 1995, the first year of the two-year study. At Lake Naivasha, P. carbo lucidus bred primarily during April-June. There was no evidence of a consistent increase in prey in the lake during this period, and the timing did not appear to result from any other consistent environmental-response adaptation. However, the onset of the main rains appeared to be an important stimulant. Based on studies by others, this subspecies breeds during April-June throughout sub-Saharan Africa, irrespective of the local rainfall regime or differences in photoperiod trend. While nesting at Lake Naivasha, a large portion of the colony appeared to forage at other locations. It is suggested that breeding timing at Lake Naivasha may be controlled by the combination of an increase in prey abundance generally throughout sub-Saharan Africa during April-June, the subspecies' nearly 12-month endogenous reproductive cycle, and the onset of the main rains. A significant seasonal decline in reproductive success was observed. Combining the two years, the mean number of chicks fledged by the first third of pairs to start laying (2.9) was significantly greater than that of the last third (1.2). The primary reason appeared to be the greater age (and experience) of the early-breeding pairs. Egg or chick predation did not seem to be an important factor, even for late breeding pairs. Breeding interference by hungry chicks from earlier broods appeared to be an important factor limiting the reproductive success of late-breeding pairs. In the first year of the new colony, the earliest-breeding pairs (first third) preferentially selected canopy-top nest sites (76%) vs. sites below the canopy (24%). They also built significantly larger nests than later-breeding pairs. Canopy-top locations and larger nests had significant positive effects on brood size and fecundity in the colony's first year but not in its second year.

The role of seabirds as indicators of marine conditions is widely acknowledged. As top predators they are vulnerable to environmental change. The study of spatial ecology has been identified as critical to the conservation of seabirds. The studies described within this thesis have for the first time explored in detail the spatial distribution of breeding fulmars. A combination of geolocation (GLS) and GPS tracking during incubation and chick rearing found that fulmars ranged further and for longer during incubation, with little difference between the sexes (Chapter 2). GLS tracking data from this period suggested that some birds were foraging at the Mid Atlantic Ridge, far surpassing the assumed maximum foraging range of this species whilst breeding. This was confirmed from the GPS track of one bird. Search behavior during the trip suggests that this bird exploited prey resources associated with fronts at the Charlie Gibbs Fracture Zone (Chapter 4). Whilst foraging far from the breeding site may allow birds to avoid competition and exploit predictable prey patches, this wide ranging behaviour may expose birds to threats such as fisheries bycatch. The majority of female fulmars tracked during the pre laying exodus foraged within the Norwegian Sea (Chapter 3), where it is estimated that 20,000 fulmars die annually on longlines. A double-tagging study, the first in the North Atlantic region and the first on a petrel species, used a state-space model to estimate the error in GLS data from fulmars and reconstructed the most probably route travelled. These data indicate that during this early period of the breeding season when distribution was virtually unknown, fulmars from a Scottish colony were foraging widely within three broad biogeographical regions. Meanwhile, fine-scale GPS tracking data was collected at three colonies during the chick rearing period. When combined with environmental and fisheries data within a model this facilitated investigation into the habitat preference of fulmars, finding associations between fulmar presence and fisheries activity, as well as oceanography (Chapter 5). This thesis describes how the use of telemetry has for the first time linked breeding season foraging characteristics with spatial distribution and habitat. Tracking has revolutionized our knowledge of fulmar distribution, behavior and habitat preference during the breeding season.

Gannets were studied on the Bass Rock (Scotland) between 1960 and 1963, and particularly in a colour ringed group (the observation colony). The account is in two parts (general breeding biology and behaviour) which are amalgamated in this brief summary. The entire Gannet population of the Bass was estimated in June 1962 and a considerable increase over the 1949 population (last count) shown (about 4,800 pairs in 1949 to about 7,000 pairs in 1962, excluding 'club' birds). The increase in the observation colony was mapped in detail, for the period of the study. The mid-cliff regions of the Rock are the first to be re-populated each year. In the observation colony (and presumably in all areas) old pairs return before newer ones, and males before females. The maximum seasonal stay at the breeding Colony is from late January to early November. During this period both sexes actively defend the nest site by fierce fighting, where necessary, and a special aggressively-motivated 'ownership' display, bowing (analysed in detail). Sites are guarded continuously and males gather nest material throughout (females only after egg laying and for a much shorter period). Nest sites and mates are usually permanent, though females show less attachment to the site than do males (an attempt to separate the two effects is made). New sites (which may be on cliff ledges of various sizes or on flatted ground) are established only by males usually four years old (beginning in April) and are held a year before breeding is attempted. Birds tend to return to the same small area of the Colony from which they originated. Site establishment normally involves fighting (discussed in detail). Pair formation takes place only at the site; the male performs an advertising display - a modified form of bowing and females 'prospect' for such males. Males are conspicuously aggressive to females - especially in new pairs but also throughout life - and females show a high tolerance of male attack and an appeasement posture (facing-away) restricted to this situation. Males bite their mates whenever they meet on the site, and the pair then perform a prolonged 'friendly' meeting ceremony (mutual fencing). This, like male advertising, is a modified form of bowing. Laying begins late March or early April and continues (by first-time breeders) until late June or exception- ally the first half of July. Older females lay earlier and produce heavier eggs. Greater density also probably causes earlier and more closely synchronised laying. Incubation behaviour in both sexes was, in some cases, released by donated eggs, but others were refused close to the laying date of the pairs concerned. Males take slightly longer incubation stints than females. No two-egg clutches (except the product of different females) were found, though Gannets usually replace a lost egg in 6 - 32 days (first-time breeders significantly less often than experienced females). However two eggs are incubated as successfully as one. The incubation period, 43.6 days, is the same for new and experienced birds. Eggs lose 10 - 13% in weight during incubation (under- foot). Eggshells are not systematically removed. Hatching success for birds breeding at least the third time was 86% and for first-time breeders 62.5%. The nidicolous young may be fed immediately on hatching. Feeding, by incomplete regurgitation, continues for the entire pre-fledging period (no starvation period). The length of attendance spells drops sharply after hatching. Even during the phase of maximum chick growth, the pair spend some 15% of daylight hours together at the nest. The young reach a maximum of 150% of the adult weight. Starvation among chicks was never found during the study period. Juveniles leave the nest at about 90 days (both from new and experienced breeders). However the former lost more small chicks and had much lower overall success (49% of eggs laid gave fledged young in new pairs, 82% in experienced pairs). The growth of young was followed in detail. Parents do not discriminate in favour of their own young and will accept substitutes, probably at any stage in the chick's growth, and even when natural and foster chicks differ markedly in age. However adults repel wandering chicks and even attack unguarded ones. Furthermore, chicks normally stay strictly on their nests. These factors prevent doubling up. Artificially twinned nests revealed that if the chicks were of about the same age both survived and were adequately fed, though fledging at about 94 days and growing slightly slower than singles. A significant age difference (three or more days) however led to the persecution of the younger by the older and hence its starvation. Excluding such cases, pairs with twins gained an 80% reproductive advantage in 1962, the year of the experiment. The implications of the twinning results are discussed together with other factors (deferred maturity, non-breeding population, etc.) affecting recruitment rate. Return of colour ringed adults over the three years of the study gave a 6% annual adult mortality and thus a life expectancy of 16.2 years. Mortality between fledging and returning to breed is calculated to be about 80%. The ontogeny of behaviour in chicks is described. Juveniles show characteristic pre-leaving behaviour and fly well at the first attempt, though cannot rise for some days having alighted. They are not accompanied by parents and do not return to the nest. Adults tend to attack them on the sea. They may return to the breeding Colony in their first year, but do not normally do so until two or three years old. Immature plumage stages are described and illustrated. Body maintenance activity (preening, sleeping, plumage shaking, etc.) is described. Rotary head shaking is a response to peripheral tactile stimulation and occurs as a probable displacement reaction in some fear situations. The ordinary sideways head shake is shown to be a simple movement which has been incorporated into several complex displays and also occurs alone, in ritualised form, in at least one signal situation. Social behaviour away from the nesting site is discussed and contrasted (in complexity) with breeding behaviour. A special posture (sky-pointing) which precedes and accompanies movement away from the site is discussed here. Its comparative occurrence within the Sulidae is also discussed. Finally adaptations to cliff nesting in the Gannet and Kittiwake are compared. The two show many similarities, evolved convergently, but also several important differences (apart from those inevitably resulting from dissimilar phylogeny). The general discussion centres round the importance of the site and associated aggression in the Gannet's breeding biology.

In this study I investigated Procellariiformes (albatrosses, petrels and shearwaters) at sea in the southwestern Atlantic Ocean. Fourteen species and 301 individuals were sampled non-destructively using a cast net method described here. A method is described for ageing Atlantic Yellow-nosed (Thalassarche chlororhynchos) and Black-browed (T. melanophris) Albatrosses based on bill colour and moult. Procellariiformes appear to have two distinct moulting strategies: petrels and shearwaters have complete annual moult, start to moult during the breeding period, and replace several primaries and tail feathers at one time, whereas albatrosses undergo long moulting cycles, replace less feathers at once, and suspend the wing moult during breeding periods. Primary moult starting at P2 rather than P1 was demonstrated to be a common feature in this taxon, with important implications for studies of stable isotopes, trace elements and pollutants in feathers. Overlap between moulting and breeding is demonstrated to be common with tail and contour feathers, but limited in wing, which suggests that flight constraint in long distance foragers rather than nutritional and energetic limitations is the ultimate factor determining primary moult timing. Based on molecular sexing and linear measurements, sexual size dimorphism was shown to vary according to species, with females in general smaller than males, more pronounced in bill measurements than in other traits, and more conspicuous in Giant Petrels (Macronectes spp.) and Diomedea albatrosses. Closely related species pairs of Thallassarche albatrosses and Procellaria petrels had differing levels of sexual dimorphism. The pelagic seabird community sampled comprises birds from different ages and breeding status according to species. Skewed Adult Sex Ratio (ASR) has been proposed as a common pattern in birds, frequently biased towards males and with larger biases in globally threatened species. In albatrosses and petrels, differential mortality of one gender in fisheries is suggested to be caused by sexual size dimorphism giving males a competitive advantage, which allows more access of the larger sex to discards and baits, or to at sea segregation of sexes. These hypotheses were tested by sampling birds at sea and reviewing ASR of birds incidentally captured in fisheries. Skewed ASR is common in albatrosses and petrels from the community attending vessels, but there was no correlation between skewed ASR and conservation status, both in terms of population size or global level of threat, or between ASR and sexual size dimorphism. Thus, sexual dimorphism in size does not explain skewed ASR in the community sampled or in incidental captures in fisheries reported in the review. Differential at sea distributions of males and females appear to explain better the patterns found in the community sampled at sea, as well as skewed ASR in seabird fatalities. Kernel density analysis of satellite tracked Spectacled Petrels (Procellaria conspicillata) in 2006 and 2007 demonstrated intense use of waters in the Brazilian Exclusive Economic Zone, from 26 to 31S, mainly over the continental shelf break and offshore waters. The marine habitats used by Spectacled Petrel and described by bathymetry, SST and productivity are remarkably different from those of the sister species White-chinned Petrel (Procellaria aequinoctialis), which occurs in the area during the winter, but remains over the continental shelf, on Sub-Antarctic and oligotrophic waters. A close association between birds and pelagic longline fishery was demonstrated through comparison of the main kernel areas used by Spectacled Petrels and the pelagic longline fleet. Stable isotopes of nitrogen (δ15N) and carbon (δ13C) in blood preserved in different ways and simultaneously growing feathers were analysed in Spectacled Petrel. Mean δ13C and δ15N values in growing feathers were higher than in blood, suggesting tissue-specific fractionation. Different methods of preserving tissues such as blood may bias stable isotope values. Air drying is proposed as a practical and unbiased method for blood preservation in field situations where freezing is not a practical option, and a mathematical approach is suggested to permit comparison between studies using different preservation methods or tissues. By analysing stable isotopes in blood of all species of Procellariiformes sampled it is demonstrated that availability of discard, mainly the preferred shark liver, which is shared among species with contrasting body masses and feeding techniques, is the ultimate cause of overlapping in trophic levels. Carbon isotopic signature overlapped among the species and was typical of subtropical and offshore region. Early migrant individuals from Antarctica and sub-Antarctic (e.g. Cape Petrel Daption capense, White-chinned Petrel, Wilson’s Storm-petrel Oceanites oceanicus) and species still rearing chicks when sampled (Wandering Albatross Diomedea exulans) had clear carbon isotopic signatures from the austral region. All southern latitude species underwent a clear shift in carbon and nitrogen isotope signatures, increasing in trophic level after arriving in the SW Atlantic. Cory’s Shearwater (Calonectris diomedea), the only species not attending vessels, has low nitrogen values resulting from a diet of flyingfish and squids naturally occurring in the area. While some abundant and widespread petrels and shearwaters, particularly those small in size, benefit from discards from pelagic longline vessels, the balance between benefits and the incidental mortality in hooks is negative for albatrosses and some petrels. Information on bycatch rates of seabirds in the Brazilian domestic pelagic longline fishery from 2001 to 2007 in the Exclusive Economic Zone and adjacent international waters of the southwestern Atlantic Ocean is presented, and bycatch rates for the area are reviewed. Overall, seabird capture rate for the Brazilian pelagic longline fleet was 0.229 birds/1000 hooks, varying from zero to 0.542 birds/1000 according to season. Capture rates were higher between June and November (cold season) and affected mainly the Black-browed Albatross (55% of birds captured), the White-chinned Petrel, the Spectacled Petrel and the Atlantic Yellow-nosed Albatross. Capture rates previously reported in the SW Atlantic varied from 0 to 5.03 birds/1000 hooks, with those based on logbooks or fishermen interviews tending to underestimate capture rates, whereas those based on small numbers of hooks or short time periods tend to greatly overestimate rates in both pelagic and demersal longline fisheries. A range of poorly-known hook-and-line commercial fisheries carried out by the Itaipava fleet, southeastern Brazil, composed by 497 vessels, was described with seven fisheries defined. Capture rates were higher for the surface longline for Dolphinfish (0.15 birds/1000 hooks and 1.08 turtles/1000 hooks), slow trolling for Bigeye Tuna (0.41 birds/day) and handlining targeting Yellowfin Tuna (0.61 birds/day). Bycatch of 47 seabirds, mainly the endangered Spectacled Petrel, Atlantic Yellow-nosed, and Black-browed Albatrosses, and 45 turtles of four species were recorded. Longline and other hook-and-line fisheries are the major threat for albatrosses and petrels from different origins when foraging in the SW Atlantic Ocean, and require urgent conservation measures.

Age-related variation in demographic rates has significant consequences for population and evolutionary dynamics, and understanding the processes driving such variation is therefore an important aspect of evolutionary ecology. Reproductive performance may vary over the lifetime of an individual, and this may be the result of both variations in reproductive effort and changes in individual competency. For example, increasing experience is likely to have beneficial effects on reproduction during early life, and senescence, or declines in physiological function, may have negative impacts on the performance of older individuals. The rate at which these changes occur can vary dramatically between species, and even between individuals of the same species. However, understanding the causes and consequences of this variation in the rate of ageing is not always straightforward. As well as the individual-level processes described, the phenotypic composition of successive age classes will contribute to age-related variation observed at the population level. Abrupt changes in performance, such as the poor performance of first time breeders, may be obscured if individuals vary in their age at first reproduction. Population-level patterns may also be influenced by selection; for example, the selective disappearance of low quality individuals from older age classes may mask senescent declines in the performance of longer-lived individuals. Moreover, the physiological mechanisms that underpin within-individual changes in performance are not well understood. Unravelling the drivers of such age-related variation requires longitudinal data, following individuals throughout their lives, which presents challenges for the study of natural populations. Albatrosses are among the longest lived vertebrates. In this thesis, I use data from three species of albatross breeding at Bird Island, South Georgia (54°00’S, 38°03’W) to explore age-related variation. Focusing primarily on the wandering albatross, Diomedea exulans, I characterise the relationship between age and various reproductive traits, and decompose the population-level patterns to reveal effects of experience, senescence and terminal effects across the reproductive lifespan of individuals. I then consider foraging behaviour as a proximate driver of changes in reproductive performance in this species. Using tracking data collected over a 20 year period, I find limited evidence for age-related variation in foraging trips taken throughout the breeding cycle. Going one step further, I explore telomere dynamics in the wandering albatross, examining the potential for telomere length to act as a physiological marker of individual state. Finally, I move on to a species comparison, incorporating data from the black-browed (Thalassarche melanophris) and grey-headed albatross (Thalassarche chrysostoma). I compare the population- and individual-level ageing patterns of these three closely related species, and consider these in light of their differing life history strategies.