Aestivation Habitat Selection of a Freshwater Turtle Under Feral Ungulate Pressure: Conservation Implications

ABSTRACT

Feral ungulates are increasing globally, including across northern Australia, thereby intensifying pressures on freshwater fauna. Understanding aestivation site selection in freshwater turtles is therefore critical for conservation given heightened vulnerability during dry‐season dormancy. We quantified microhabitat characteristics associated with aestivation by the northern long‐necked turtle ( Chelodina rugosa ) across billabongs of the Arafura Swamp Indigenous Protected Area, Northern Territory. Comparing 37 aestivation sites with 32 nonaestivation points, we tested associations between site type and (i) percentage woody vegetation, (ii) large woody cover over sites and (iii) feral pig and buffalo disturbance. Aestivation sites were positively associated with woody vegetation and large woody cover (GLMMs; both p  < 0.01). They were also positively associated with feral pig disturbance ( p  < 0.05), consistent with active predation on buried turtles, and negatively associated with buffalo disturbance ( p  < 0.05). Because woody cover predicted aestivation sites, we compared temperature variables at median aestivation depth (13.5 cm) between dense (‘closed’) and more open (‘open’) woody microhabitats. Closed sites were significantly cooler and less variable across all daily temperature metrics. These results show that C. rugosa selects microhabitats that reduce exposure to buffalo impacts and thermal extremes but may remain vulnerable to pig predation. Populations in less wooded wetlands may therefore face heightened risk under increasing ungulate pressure and climate variability. Retaining or restoring large woody structure in tropical wetlands is likely to enhance aestivation refugia and support long‐term population persistence.