An outback oasis: the ecological importance of bilby burrows

Abstract

Ecosystem engineers are species that have a role in creating and maintaining certain habitat traits that are important for other species. Burrowing species do this by creating subterranean refugia from predation and thermal extremes, but also providing foraging opportunities through soil movement and by increasing local landscape heterogeneity. In this study, we used camera traps to monitor the burrows of greater bilbies (Macrotis lagotis), a vulnerable Australian marsupial, in an area subject to frequent disturbance by fire. We tested the hypothesis that bilby burrows provide refuge for other species and therefore their presence increases biodiversity. In total, 45 taxa – 22 bird, 16 reptile and 7 mammal taxa – were recorded interacting with 127 burrows across 7 sites. Species richness was greater at burrows compared with vegetation away from burrows, while abundance was no different. There was no difference in species assemblage for bilby burrows that were actively maintained by bilbies compared with abandoned burrows, although there was more activity at bilby maintained burrows. A wildfire allowed us to test the ad hoc hypothesis that the use of bilby burrows was greater when vegetation cover was removed by fire. We recorded significant differences in species assemblage interacting with burrows after fire, although overall species richness and abundance did not change. The response of individual species was variable; for example, burrows provide a refuge for smaller species (such as mice and small reptiles), and may therefore protect them from the effects of fire. Where they persist, bilbies provide an important ecosystem engineering service, as their burrows support a broad range of species. Further reduction in the distribution of the bilby is therefore likely to have a flow‐on effect on biodiversity, impacting species that use their burrows for refuge.

Burrow webs: Clawing the surface of interactions with burrows excavated by American badgers

“…Prior to our work, no study has explored the species that utilize abandoned badger burrows, despite similar questions being addressed for other fossorial mammals (e.g., Davidson et al., 2008 ; Dawson et al., 2019 ; Blanco et al., 2020 ; Read et al., 2008 ) along with the rich body of literature highlighting the cavity web (i.e., diversity and frequency of species secondarily using tree cavities) associated with woodpeckers (Cockle, Ibarra, et al., 2019 ; Cockle et al., 2011 ; Martin et al., 2004 ; Martin & Eadie, 1999 ). Our study has provided insight concerning the role of habitat provisioning by American badgers, which has substantial consequences on how we conceptualize badgers as ecosystem engineers.…”

“…and kangaroo rats ( Dipodomys sp. ; Davidson et al., 2008 ), bettongs ( Bettongia lesueur ; Read et al., 2008 ), aardvarks ( Orycteropus afer ; Whittington‐Jones et al., 2011 ), greater bilbies ( Macrotis lagotis ; Dawson et al., 2019 ), giant armadillos ( Priodontes maximus ; Blanco et al., 2020 ), and gopher tortoises (Murphy et al., 2021 ). Many other burrow excavators remain (e.g., Davidson et al., 2012 ), however, and additional work is required to expand the understanding of how burrowing animals influence ecological communities.…”

Excavations of giant armadillos alter environmental conditions and provide new resources for a range of animals

“…The threshold for two consecutive detections of the same species at same site to be considered independent records was 1 h, leaving a total of 802 independent vertebrate records. To avoid the use of subjective interpretation of behaviors from photographs, and for comparative purposes, we categorized records combining spatial (Dawson et al , 2019) and temporal (Desbiez & Kluyber, 2013) thresholds based on continuous photographs. We categorized all captures into one of three categories: (1) any animal caught passing on camera but not within the target area (i.e., burrow or spoil pile) was classified as ‘passing’, (2) an ‘interaction’ occurred when the animal occupied the target area for less than 5 s and (3) we considered ‘use’ when the animal spent over 5 s within the burrow or spoil pile area.…”

Burrowing by translocated boodie (Bettongia lesueur) populations alters soils but has limited effects on vegetation

“…As ecosystem engineers (sensu Jones et al., 1994), digging mammals influence geomorphological processes (Butler, 1995) and soil resources, creating shelter for other animals (e.g., Dawson et al., 2019; Whittington‐Jones et al., 2011) and affecting vegetation and soil biota (Davidson et al., 2012; Fleming et al., 2014). However, due to complex interactions between the digging species, habitat and soil characteristics, and the extent and longevity of the burrows or warrens, the effects of digging mammals on soil and vegetation properties vary (Mallen‐Cooper et al., 2019).…”