The relation between environmental conditions, park management and chronic stress in fallow deer (Dama Dama).

Abstract

Nowadays increased attention shows for the welfare of wildlife among the public, for instance the welfare implications for the housing of Fallow Deer in the Netherlands and the United Kingdom. Positive welfare is a state in which the animal has the freedom to adequately react to his living conditions and hence can reach a state which it perceives as positive. Under conditions of chronic stress, this adaptability may be compromised. Chronic stress results in impaired negative feedback of the hypothalamus-pituitary-adrenal axis, leading to prolonged and excessive release of cortisol in the circulation, followed by the accumulation of cortisol in hair over the course of weeks/months. Deer samples were obtained for fallow deer from the Amsterdamse Waterleidingduinen, the Netherlands and the different deer parks in the United Kingdom. In this study, brain samples these deer were sliced for the analysis of corticosteroid receptor levels in deer hippocampus, and an ELISA was conducted to measure the levels of cortisol in hair samples of these same deer.

The results from the AWD showed that the cortisol levels from the winter of 2015/2016 were significantly higher than from the winter of 2016/2017. that population density might be an important factor in chronic stress in fallow deer.

The data from the United Kingdom was analysed for possible correlations between the cortisol levels and the different park factors. Supporting the finding of the AWD, was the fact that for the UK data a trend towards significance was shown for the fallow deer density. When including also red deer, a significant correlation was found between the levels of cortisol and the total deer density. This can be explained by the experienced social stress and food availability. When comparing different cull winters, a significant difference was found, suggesting climate could also be an important factor. However, when considering the climate differences between the parks, only the average temperature in May and June was found to be significantly correlated with hair cortisol. Higher temperatures in May and June increases the germination and the growth of grass and therefore likely reflects increased food availability. Human disturbance showed a negative correlation with the levels of cortisol in hair, although this was only a statistical trend. This negative correlation might be explained by habituation of deer to the public in parks with high levels of human interference.

In conclusion, a substantial factor in the welfare of fallow deer are population density and the average temperature in May and June, which can be explained by experienced social stress and low food availability.