Landscape change is a key driver of biodiversity declines due to
habitat loss and fragmentation, but spatially shifting resources can
also facilitate range expansion and invasion. Invasive populations are
reproductively successful, and landscape change may buoy this success.
We show how modelling the spatial structure of reproductive success
can elucidate the mechanisms of range shifts and sustained invasions
for mammalian species with attendant young. We use an example of
white-tailed deer (deer; Odocoileus virginianus ) expansion in
the Nearctic boreal forest, a North American phenomenon implicated in
severe declines of threatened woodland caribou (Rangifer
tarandus ).
We hypothesized that deer reproductive success is linked to forage
subsidies provided by extensive landscape change via resource
extraction. We measured deer occurrence using data from 62
camera-traps in northern Alberta, Canada, over three years. We weighed
support for multiple competing hypotheses about deer reproductive
success using multi-state occupancy models and generalized linear
models in an AIC-based model selection framework.
Spatial patterns of reproductive success were best explained by
features associated with petroleum exploration and extraction, which
offer early seral vegetation resource subsidies. Effect sizes of
anthropogenic features eclipsed natural heterogeneity by two orders of
magnitude. We conclude that deer populations are likely buffered from
overwinter mortality by landscape change, wherein early seral forage
subsidies support high springtime reproductive success to offset or
exceed winter losses.
Synthesis and Applications . Modelling spatial structuring in
reproductive success can become a key goal of remote camera-based
global networks, yielding ecological insights into mechanisms of
invasion and range shifts to inform effective decision-making for
global biodiversity conservation.
Key-words: fitness, invasive species, camera trapping,
multistate occupancy models, reproduction, range shifts, landscape
change