Reproductive state of hunted female mammals during 2000-2015 in Nueva Esperanza, Peruvian Andes

The annual birthrate of female offspring and the intrinsic rate of natural increase (rmax) of populations are key reproductive parameters in models for assessing hunting sustainability or population viability of species. We calculated wild birthrate (pregnancy rate) for ten mammal species, using 180 months (from 2000 to 2015) of reproductive data from 950 hunted female animals collected with the participation of local hunters in the Peruvian Amazon. The methodology assured that no animals were killed outside the hunter's normal activities. The data included shows the reproductive state (pregnant or non-pregnant) of all collected individuals (n=1090), related to the date of collection. Hunters registered required data from genital organs from 950 (87.2%) hunted females, and 140 (12.8%) collected tracts lacked the collection date due to lost or non-legible individual sample codification.

(Table 1) Breeding parameters for 60 male Adélie penguins (Pygoscelis adeliae) at station Dumont d'Urville (Antarctica) depending on treatment (control vs. CORT)

Corticosterone, the main stress hormone in birds, mediates resource allocation, allowing animals to adjust their physiology and behaviour to changes in the environment. Incubation is a time and energy-consuming phase of the avian reproductive cycle. It may be terminated prematurely, when the parents' energy stores are depleted or when environmental conditions are severe. In this study, the effects of experimentally elevated baseline corticosterone levels on the parental investment of incubating male Adelie penguins were investigated. Incubation duration and reproductive success of 60 penguins were recorded. The clutches of some birds were replaced by dummy eggs, which recorded egg temperatures and rotation rates, enabling a detailed investigation of incubation behaviour. Corticosterone levels of treated birds were 2.4-fold higher than those of controls 18 days post treatment. Exogenous corticosterone triggered nest desertion in 61% of the treated birds; consequently reducing reproductive success, indicating that corticosterone can reduce or disrupt parental investment. Regarding egg temperatures, hypothermic events became more frequent and more pronounced in treated birds, before these birds eventually abandoned their nest. The treatment also significantly decreased incubation temperatures by 1.3 °C and lengthened the incubation period by 2.1 days. However, the number of chicks at hatching was similar among successful nests, regardless of treatment. Weather conditions appeared to be particularly important in determining the extent to which corticosterone levels affected the behaviour of penguins, as treated penguins were more sensitive to severe weather conditions. This underlines the importance of considering the interactions of organisms with their environment in studies of animal behaviour and ecophysiology.