Definition of the ecological niche used in this article.

(A) The environmental space can be represented as a set of axes (here, two: X, Y), each representing a gradient of resource or condition. A species' niche is defined as the range of each of these gradients that the species can exploit/occupy/cope with (yellow ellipse). The projection of the niche on each gradient is defined by a position (P_x, P_y) and a breadth (red solid lines). In our analyses, we consider two axes: (B) a thermal axis (referred to in the text as ‘thermal niche’) corresponds to a gradient of temperature; (C) a habitat axis (‘habitat niche’) refers to a gradient of vegetation structure ranging from mature forest to grasslands and open fields (see also Table 1).