Ecology of the rare but irruptive Pilliga mouse, Pseudomys pilligaensis. V. Relationships with yellow-footed antechinus, Antechinus flavipes, and house mouse, Mus domesticus

Abstract

We investigated relationships between <i>Pseudomys pilligaensis</i> and other small mammal species in terms of their population fluctuations and habitat selection during a population irruption of <i>P. pilligaensis</i>. <i>Antechinus flavipes</i> showed only seasonal fluctuations in numbers, suggesting that it did not respond to the same environmental factors as <i>P. pilligaensis</i>. <i>A. flavipes</i> consistently selected areas with less sand in all phases of the irruption of <i>P. pilligaensis</i>, resulting in a clear separation from <i>P. pilligaensis</i> except in the Peak phase of the latter's irruption. Numbers of <i>Mus domesticus</i> fluctuated similarly to <i>P. pilligaensis</i> until the latter's irruption peak in April 2000. However, <i>M. domesticus</i> disappeared after July 2000 from our sites. <i>M. domesticus</i> seemed to occupy the area only temporarily when seeds were abundant. In the Increase and Peak phases of the irruption of <i>P. pilligaensis</i>, <i>M. domesticus</i> occupied core habitats characterised by more sand and shrub, and less litter, while in the Low phase <i>P. pilligaensis</i> occupied the core habitats that <i>M. domesticus</i> used to occupy. This may suggest that <i>M. domesticus</i> was excluded from core habitats through competition with <i>P. pilligaensis</i> in the Low phase of the latter's irruption. However, since increased anthropogenic disturbance might create conditions that <i>M. domesticus</i> prefers, it is important to assess carefully any impacts of such disturbance on <i>P. pilligaensis</i>.