European wild rabbit (Oryctolagus cuniculus) is a widely distributed species with a multiple role in both environmental sustainability and local economy. In the current study we examine the body condition of the species in relation to habitat type, age, sex and seasonality on the island of Lemnos. Body condition was assessed based on a visual estimation of the amount of abdominal fat. A high intra-annual variation in the body condition of the species has been observed, which is further affected by sex and age. The species appears to conserve and maintain high levels of energy reserves for two main reasons. The first is to ensure a better reproductive success,
as expressed by the relatively high amount of stored fat reserves at the onset of breeding season, and their depletion during it. The second
is to ensure survival during periods where the shortage of food creates a rather hostile environment, as expressed by the increased level of reserves during summer and their dramatic decrease from late summer until autumn. The temporal fluctuation in energy reserves differs between male and female rabbits, reflecting their temporally different energy demands. Further, differences in body conditions were observed between juvenile and adult individuals, reflecting their different needs in terms of body growth and maintenance. Our results could offer important insights for the development of a time specific management plan and measures to ensure either the control of the population or its conservation.
Sibling competition leading to physiological stress and elevated allostatic load is driven by asymmetrical development and limited resources. To investigate these predictions, we studied broods of the lesser kestrel Falco naumanni, from a nest-box population in Armenio, Central Greece. For each nestling reared in nest-boxes, we noted the age (in days) since hatching, measured the wing chord length and body mass. We also clipped the central right rectrix for ptilochronology for subsequent analysis in the laboratory. We measured 206 nestlings from 61 broods (range 2-5 nestlings). In the case of nestlings < 18 days old (n = 198, 96.1% of all) we also measured the length of feathers. As a measure of body condition, we used the residuals of the linear regression for the relationship between wing chord length and body mass, while the growth bar width of feathers was used as a second, independent index of body size and allostatic load. A GLMM and information-theory criterion showed that both measures of body condition decreased incrementally from the first sibling to the most subordinate in the brood. Body condition of subordinate siblings was influenced by the number of siblings in the nest; i.e. the larger the brood size the greater the discrepancy in body condition between siblings. At the same time, we did not find any influence of sex on either measure of fitness. Thus, our results indirectly support the hypothesis that sibling competition may cause physiological developmental stress which is reflected in decreased body condition and increased allostatic load for younger nestlings.