TY - JOUR
T1 - Declines in greater bilby (Macrotis lagotis) geographic range and realised niche are best explained by the invasive red fox (Vulpes vulpes)
AU - Geyle, Hayley M.
AU - Young, Alys R.
AU - Murphy, Brett P.
AU - Dickman, Chris R.
AU - Schlesinger, Christine
AU - Dixon, Kelly M.
AU - Moore, Harry
AU - Legge, Sarah
AU - Silcock, Jennifer
AU - Indigo, Naomi
AU - Dziminski, Martin
AU - Greatwich, Bruce
AU - Newsome, Thomas M.
AU - Paltridge, Rachel
AU - Southgate, Rick
AU - Arkinstall, Cassandra
AU - Bradley, Kevin
AU - Central Land Council Rangers, null
AU - Jackett, Nigel
AU - Kanyirninpa Jukurrpa Rangers, null
AU - Karajarri Rangers, null
AU - Kiwirrkurra Rangers, null
AU - Kimberley Land Council, null
AU - Moore, Danae
AU - Ngurrara Rangers, null
AU - Parna Ngururrpa Aboriginal Corporation, null
AU - Nyangumarta Rangers, null
AU - Nyikina Mangala Rangers, null
AU - Skroblin, Anja
AU - Southwell, Darren M.
AU - Tait, Laurie
AU - Webeck, Kim
AU - Wiluna Martu Rangers, null
AU - Yawuru Country Managers, null
AU - Banks, Sam
PY - 2025/2
Y1 - 2025/2
N2 - Understanding the factors driving species’ range and niche contractions can help us identify how and where threats to those species are being mediated or tolerated. Here, we used the ‘niche reduction hypothesis’ to investigate changes in the geographic range and realised niche of the greater bilby (Macrotis lagotis). We compiled bilby occurrence records to estimate changes in the geographic range (extent of occurrence, EOO) and realised niche for two time periods: historical (1900–2022) and contemporary (2000−2022). We used one-class support vector machine models to measure realised niche size, comparing decline in realised niche to decline in EOO through time. Ecological niche models (ENM) were then used to quantify environmental factors influencing the historical and contemporary realised niche, and to determine the extent to which environmental conditions may mediate threats (particularly introduced predators). Bilby EOO declined by 70% through time, while realised niche size declined by 46%. Fire frequency was an important predictor in both the historical and contemporary ENMs, while red fox (Vulpes vulpes) density became important only in the contemporary ENM, suggesting that foxes are contributing to contemporary bilby declines. Bilbies contracted to areas with lower fox densities, lower average normalised difference vegetation index values, higher fire frequency, and higher average temperatures. Environmental conditions likely limit fox distribution (leading to contraction of bilbies to fox-free areas) and/or mediate fox impacts (leading to greater population resilience to fox predation). Future research should enhance understanding of how environmental factors facilitate predator impacts and how these vary across environmental space. Such knowledge will likely improve understanding of how to manage threats facing bilbies across their distribution.
AB - Understanding the factors driving species’ range and niche contractions can help us identify how and where threats to those species are being mediated or tolerated. Here, we used the ‘niche reduction hypothesis’ to investigate changes in the geographic range and realised niche of the greater bilby (Macrotis lagotis). We compiled bilby occurrence records to estimate changes in the geographic range (extent of occurrence, EOO) and realised niche for two time periods: historical (1900–2022) and contemporary (2000−2022). We used one-class support vector machine models to measure realised niche size, comparing decline in realised niche to decline in EOO through time. Ecological niche models (ENM) were then used to quantify environmental factors influencing the historical and contemporary realised niche, and to determine the extent to which environmental conditions may mediate threats (particularly introduced predators). Bilby EOO declined by 70% through time, while realised niche size declined by 46%. Fire frequency was an important predictor in both the historical and contemporary ENMs, while red fox (Vulpes vulpes) density became important only in the contemporary ENM, suggesting that foxes are contributing to contemporary bilby declines. Bilbies contracted to areas with lower fox densities, lower average normalised difference vegetation index values, higher fire frequency, and higher average temperatures. Environmental conditions likely limit fox distribution (leading to contraction of bilbies to fox-free areas) and/or mediate fox impacts (leading to greater population resilience to fox predation). Future research should enhance understanding of how environmental factors facilitate predator impacts and how these vary across environmental space. Such knowledge will likely improve understanding of how to manage threats facing bilbies across their distribution.
KW - Introduced species
KW - Niche decline
KW - Niche reduction hypothesis
KW - Range contraction
KW - Threatened species
KW - Threatening process
UR - http://www.scopus.com/inward/record.url?scp=85211737509&partnerID=8YFLogxK
U2 - 10.1016/j.biocon.2024.110872
DO - 10.1016/j.biocon.2024.110872
M3 - Article
AN - SCOPUS:85211737509
SN - 0006-3207
VL - 302
SP - 1
EP - 13
JO - Biological Conservation
JF - Biological Conservation
M1 - 110872
ER -