Emerging infectious diseases (EIDs) of free-living wild animals can be classified into three major groups on the basis of key epizootiological criteria: (i) EIDs associated with “spill-over” from domestic animals to wildlife populations living in proximity; (ii) EIDs related directly to human intervention, via host or parasite translocations; and (iii) EIDs with no overt human or domestic animal involvement. These phenomena have two major biological implications: first, many wildlife species are reservoirs of pathogens that threaten domestic animal and human health; second, wildlife EIDs pose a substantial threat to the conservation of global biodiversity.

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Emerging Infectious Diseases of Wildlife-- Threats to Biodiversity and Human Health

This review is focused on the acute form of infectious bursal disease (IBD) caused by very virulent IBD virus (vvIBDV). First described in Europe about 10 years ago, this new form of the disease has rapidly spread all over the world, causing dramatic losses; after a decade, it still represents a considerable threat to the poultry industry. Emergence of the acute forms of the disease has drastically changed the epidemiology of IBD. Although their origin is still under investigation, vvIBDVs have spread all over the world in a very explosive but conserved manner. This raises the question of the origin of vvIBDVs, of the possible existence of reservoirs and of the possible emergence of new, distinct lineages in the future. While it has become clear that amino acids within the variable region of virus protein VP2 account for the molecular basis of antigenic variation, no definite hot spot that determines pathogenicity has been identified. Fingerprints of VP2 on vvIBDVs have to be considered more as common evo...

https://www.tandfonline.com/doi/pdf/10.1080/03079450050045431

Acute infectious bursal disease in poultry: A review

We used quantitative fatty acid signature analysis (QFASA) to examine the diets of 1738 individual polar bears (Ursus maritimus) sampled across the Canadian Arctic over a 30-year span. Polar bear foraging varied over large and small spatial and temporal scales, and between demographic groups. Diets in every subpopulation were dominated by ringed seals (Phoca hispida) and, in the eastern Arctic, secondarily by harp seals (Pagophilus groenlandica). Beluga whales (Delphinapterus leucas) were an important food source for bears in the High Arctic, which is consistent with previous anecdotal reports. Foraging patterns were most similar among neighboring subpopulations with similar prey assemblages, but also differed geographically within Western Hudson Bay. The sexual size dimorphism of polar bears had an important effect on foraging, as large bearded seals (Erignathus barbatus) and walruses (Odobenus rosmarus) were consumed most often by older, male bears, whereas ringed seals and, where available, harbor seals (P. vitulina) were most important to younger age classes. Larger, older bears also had the greatest dietary diversity, apparently because of their ability to include larger-bodied prey. During spring and summer, polar bears in some areas increased predation on migratory harp seals and beluga whales. In Western Hudson Bay, bearded seal consumption declined between 1995 and 2001 for both male and female bears and continued to decline among females up to the most recent sampling (2004). Ringed seal consumption in Western Hudson Bay increased between 1998 and 2001, perhaps in response to increased ringed seal productivity, but was not significantly affected by date of sea-ice breakup. Overall, our data indicate that polar bears are capable of opportunistically altering their foraging to take advantage of locally abundant prey, or to some degree compensating for a decline in a dominant prey species. However, in other areas polar bears are dependent on the availability of ringed and bearded seals. Recent population data suggest that polar bears with the most specialized diets may be most vulnerable to climate-related changes in ice conditions. The results of this large-scale, ecosystem-based study indicate a complex relationship between sea-ice conditions, prey population dynamics, and polar bear foraging.

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Polar bear diets and arctic marine food webs: insights from fatty acid analysis

Sexual segregation occurs when members of a species separate such that the sexes live apart, either singly or in single-sex groups. It can be broadly categorised into two types: habitat segregation and social segregation. Sexual segregation is a behavioural phenomenon that is widespread in the animal kingdom yet the underlying causes remain poorly understood. Sexual segregation has been widely studied among terrestrial mammals such as ungulates, but it has been less well documented in the marine environment. This chapter clarifies terms and concepts which have emerged from the investigation of sexual segregation in terrestrial ecology and examines how a similar methodological approach may be complicated by differences of marine species. Here we discuss the behavioural patterns of sexual segregation among marine fish, reptile, bird and mammal species. Five hypotheses have been forwarded to account for sexual segregation, largely emerging from investigation of sexual segregation in terrestrial ungulates: the predation risk, forage selection, activity budget, thermal niche-fecundity and social factors hypotheses. These mechanisms are reviewed following careful assessment of their applicability to marine vertebrate species and case studies of marine vertebrates which support each mechanism recounted. Rigorous testing of all hypotheses is lacking from both the terrestrial and marine vertebrate literature and those analyses which have been attempted are often confounded by factors such as sexual body-size dimorphism. In this context, we indicate the value of studying model species which are monomorphic with respect to body size and discuss possible underlying causes for sexual segregation in this species. We also discuss why it is important to understand sexual segregation, for example, by illustrating how differential exploitation of the sexes by humans can lead to population decline.

Sexual segregation in marine fish, reptiles, birds and mammals behaviour patterns, mechanisms and conservation implications.

Sexual segregation by micro- or macrohabitat is common in birds, and usually attributed to size-mediated dominance and exclusion of females by larger males, trophic niche divergence or reproductive role specialization. Our study of black-browed albatrosses, Thalassarche melanophrys, and grey-headed albatrosses, T. chrysostoma, revealed an exceptional degree of sexual segregation during incubation, with largely mutually exclusive core foraging ranges for each sex in both species. Spatial segregation was not apparent during brood-guard or post-guard chick rearing, when adults are constrained to feed close to colonies, providing no evidence for dominance-related competitive exclusion at the macrohabitat level. A comprehensive morphometric comparison indicated considerable species and sexual dimorphism in wing area and wing loading that corresponded, both within and between species, to broad-scale habitat preferences relating to wind strength. We suggest that seasonal sexual segregation in these two species is attributable to niche divergence mediated by differences in flight performance. Such sexual segregation may also have implications for conservation in relation to sex-specific overlap with commercial fisheries.

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Seasonal sexual segregation in two Thalassarche albatross species: competitive exclusion, reproductive role specialization or foraging niche divergence?

Consistent sex differences in foraging trip duration, feeding locality and diet of breeding Adelie penguins (Pygoscelis adeliae) were demonstrated at two widely separated locations over several breeding seasons. Differences in foraging behaviour were most pronounced during the guard stage of chick rearing. Female penguins made on average longer foraging trips than males, ranged greater distances more frequently and consumed larger quantities of krill. In contrast, males made shorter journeys to closer foraging grounds during the guard period and fed more extensively on fish throughout chick rearing. Mean guard stage foraging trip durations over four seasons at Bechervaise Island, Eastern Antarctica and over two seasons at Edmonson Point, Ross Sea ranged between 31 and 73 h for females and 25 and 36 h for males. Ninety percent of males tracked from Bechervaise Island by satellite during the first 3 weeks post-hatch foraged within 20 km of the colony, while the majority (60%) of females travelled to the edge of the continental shelf (80–120 km from the colony) to feed during this period.

Sex differences in Adélie penguin foraging strategies

Poultry virus infection in Antarctic penguins

This paper presents a summary of the foraging locations of Adelie penguins, determined by satellite tracking, at seven widely-spaced breeding colonies along the coast of eastern Antarctica between 55"E (Enderby Land) and 175"E (Ross Sea). Adelie penguins feeding chicks regularly travelled up to 120 km offshore to the continental shelf and returned with krill, Etlplzausza superba. Locations of penguins on foraging trips were compared with historical records of fine-scale krill catch data for the regions of interest. The potential for overlap with krill fishing occurs particularly where ice conditions permit the fishing fleet to approach the edge of the continental shelf or where penguins forage downstream from the fishery. It is suggested that the potential for overlap between foraging areas of Adelie penguins and fishable concentrations of krill be investigated before a decision is made to establish a new CEMP site.

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Heather Gardner

Papers

Sex differences in Adélie penguin foraging strategies

Poultry virus infection in Antarctic penguins

The foraging range of Adélie penguins - implications for CEMP and interactions with the krill fishery