Analysis of hares'distribution. Mapping the distribution of climate change winners (European hare and heath hare) and a climate change loser (white mountain hare) in Norway

Abstract

Assessing species distribution is important as it is traditionally used for further conservation plans in response to human disturbances such as global warming and establishment followed by invasions of non-native species. The synergistic effect of the two disturbances is affecting native and threatened white mountain hare (Lepus timidus timidus) habitat and survival in Norway. As snow-covered habitats decrease, it potentially increases habitat which can be exploited by the blue mountain hare (Lepus timidus sylvaticus) and the invasive European hare (Lepus europaeus), to the detriment of the white mountain hare. Understanding what defines a suitable habitat on a large scale using the maximum entropy algorithm (MaxEnt) is a promising approach for species conservation and management. The present study was conducted to identify the potential distribution and niche overlap of all three hares using current climatic and orographic factors in Norway. Spatially biased occurrence records in the study area can influence the program leading to potential underprediction. Addressing this issue, present information about suitable habitats and key ecological factors affecting the predicted distribution were modelled using two distinct approaches: including or not the bias file from the sampling effort. To quantify models fit and performance between models AUC evaluation was conducted. The results identified from the bias model, potentially closer to reality, the elevation, minimum temperature of the coldest quarter and precipitation seasonality as key environmental variables affecting each hare. Maximum temperature from the warmest quarter was also found affecting the invasive European hare non-bias model, which does not depict high differences from the bias model. Both mountain hare subspecies was found to share similar ecological niches and a distribution overlap was observed mainly in southern Norway. The invasive European hare might play a key role in shaping the distribution of both mountain hare morphs. From the predicted distributions the species niche and distribution were identified as overlapping with both mountain hare subspecies. Distribution matching was found in coastal areas in the central and northern parts of Norway, in addition to the south-eastern area. A potential increase in biotic interaction in Norway, from species that appears to benefit from global warming, the blue morph and the European hare, could be detrimental to the threaten white native mountain hare distribution and survival.