Activity patterns and detection rates of red-legged pademelons (

Abstract

Red-legged pademelons (Thylogale stigmatica) occur as several subspecies in eastern Australia. The northern subspecies (T. stigmatica stigmatica) in north Queensland is considered common; the southern subspecies (T. stigmatica wilcoxi) in north-eastern New South Wales is, by comparison, rare and is listed as threatened. Activity patterns should also vary between these subspecies because T. s. stigmatica emerges from the forest at night to graze, whereas T. s. wilcoxi remains in the forest throughout the 24-h cycle. Using camera traps, we detected pademelons at a greater rate at a Queensland site occupied by T. s. stigmatica than at a New South Wales site inhabited by T. s. wilcoxi; this result is consistent with their conservation status. However, pademelons at these sites displayed remarkably similar activity patterns within rainforest over the 24-h period, a result that was unexpected based on what is known of their diel behaviour.

Occurrence patterns of sympatric forest wallabies: assessing the influence of structural habitat attributes on the coexistence of Thylogale thetis and T. stigmatica

“…These differences are also reflected in their cranial morphology; Mitchell et al (2018) found that the southern subspecies of T. stigmatica ( Thylogale stigmatica wilcoxi ) had a broader cranium and a shorter and more robust muzzle—typical of browsing species, while the northern subspecies ( Thylogale stigmatica stigmatica ) possessed a more slender skull with a longer muzzle, a characteristic shared with T. thetis and that is commonly seen in grazing macropods. Direct competition for edge resources may have forced sympatric populations of T. stigmatica into a narrower niche and also driven their population density below what might be achieved in the absence of competition; our related work ( Smith, Andrew & Vernes, 2022 ; Vernes, Elliott & Elliott, 2022 ) indicated that T. stigmatica occur at lower population densities when in sympatry with T. thetis than when they occur in isolation from them. Thus, when constrained within a narrower, more specialised niche, population density of T. stigmatica may be reduced.…”

“…When sympatric, relative population densities can vary; Johnson (1977) reported T. stigmatica to be less abundant than T. thetis at an upland site at Dorrigo NSW, but McHugh et al (2019) found the opposite to be the case in the North Coast Bioregion in far north-eastern New South Wales. T. stigmatica also appears to be less abundant in the south of its range (when in sympatry with T. thetis ), compared to when it occurs as the sole pademelon species in the north of its range ( Vernes, Elliott & Elliott, 2022 ). Diet and habitat usage by the different species and sub-species of pademelons in eastern Australia is also borne out in studies of dental morphology; while both T. thetis and T. stigmatica have a dental morphology suited to browsing ( Sanson, 1989 ), differences in cranial morphology point towards T. thetis incorporating more grass in the diet than T. stigmatica generally, but for the northern sub-species of T. stigmatica to graze more than the southern sub-species ( Mitchell et al, 2018 ).…”