Within and between species competition in a seabird community: statistical exploration and modeling of time-series data.

In a changing environment, the maintenance of communities is subject to many constraints (phenology, resources, climate, etc.). One such constraint is the relationship between conspecifics and competitors. In mixed colonies, seabirds may have to cope with interspecific and intraspecific competition for both space and food resources. We applied competitive interaction models to data on three seabird breeding populations: black-legged kittiwake (Rissa tridactyla), common guillemot (Uria aalge) and Brünnich's guillemot (Uria lomvia) collected over 27-years at Kharlov Island in the Barents Sea. We found a competitive effect only for the kittiwake breeding population size on the common guillemot breeding population size when kittiwakes were abundant. The timing of kittiwake breeding negatively affected the number of breeding Brünnich's guillemots. The timing of breeding was negatively correlated to biomass of the main pelagic fish in the Barents Sea, the capelin (Mallotus villosus), which suggests an indirect action. The community matrix shows that the community was not stable. The kittiwake population did not decrease as seen in north Norwegian populations. Likewise, the common guillemot population, after a crash in 1985, was recovering at Kharlov while Norwegian populations were decreasing. Only the Brünnich's guillemot showed a decrease at Kharlov until 1999. We suggest that the stability of the kittiwake and common guillemot populations at Kharlov is due to better feeding conditions than in colonies of the Norwegian coast, linked to a possible eastward shift of the capelin population with the temperature increase of the Barents Sea.

Body reserves and nutritional needs during laying preparation in barn owls.

To investigate the composition of the body reserves made during pre-laying by breeding European barn owls (Tyto alba), we have analysed the body composition of captive breeding and non-breeding females sacrificed during the laying period. The data obtained were compared to the daily requirement for egg formation obtained by an egg composition analysis and the timing of egg synthesis. This study demonstrates that body mass gain observed in breeding females (+ 38.3 g after eggs in formation and gonadal tractus were removed) was not the consequence of an accumulation of body fuels like lipids but of mainly water and lean material. The lipidic reserves were found to be less important in breeding than in non-breeding females and their localisation modified; lipids were absent from medullar bones in breeding females which liberated room for other storage. The subcutaneous tissue, which was homogeneous in non-breeding females, was located principally under the brood patch in breeding females. Nutrients and energy required during egg formation could be obtained without modification of daily food intake. These results show that a laying event can be initiated in 14 days and that the onset of reproduction is not triggered by body condition in barn owls. The water accumulation observed is suggested to be the mere consequence of an increase of protein metabolism (egg and moult). These results intimate that the body mass increase observed in diurnal and nocturnal raptors during laying preparation, interpreted as an energy safety strategy, ought to be reconsidered.

Horny perifollicular mucinosis. An atypical pityriasis rubra pilaris-like eruption associated with HIV infection.

We present a case of pityriasis rubra pilaris (PRP)-like eruption, in association with human immunodeficiency virus (HIV) infection, clinically characterized by follicular papules with some elongated spines and comedo-like lesions. The lesions were located on the back, flanks, and proximal extremities. Orthokeratotic follicular plugs and perifollicular mucinous degeneration were consistently observed on three biopsies. The most characteristic histological features of PRP were absent. To our knowledge, this is the first reported case of this kind. Such a case could suggest an atypical PRP modified by HIV infection. It is also possible that it represents a new entity associated with advanced HIV infection (horny perifollicular mucinosis).