Association of moose parturition and post‐parturition habitat with calf survival

Abstract

Habitat use during calving and the energetically demanding post‐parturition period can be an important determinant of neonatal survival. The moose (Alces alces) population in northeastern Minnesota, USA declined 65% from 2006 to 2018. During 2013–2015, annual survival of calves was estimated as low as 28%. We remotely monitored global positioning system (GPS)‐collared adult female moose and their neonates during the calving and post‐parturition seasons to examine calving movements, birth‐sites, habitat use, survival, and cause‐specific mortality of neonates. Identifying the association of specific landscape characteristics with neonate survival should yield insight into mechanisms contributing to the declining moose population and serve as a basis for an ecologically sound management response. We compared habitat characteristics of pre‐calving, calving, peak‐lactation, and mortality sites at a fine and broad scale. We also compared calving sites of females that successfully reared a calf to winter to those that did not. In general, females tended to move to areas of more conifer cover to calve. During peak‐lactation, females and their calves used steeper areas with abundant forage and high concealment but less conifer cover. Mortalities occurred at sites that were more level than other site types. Females that successfully reared a calf to 1 February typically calved in areas with more deciduous forest and less forested wetland cover than females whose calves died before 9 months of age. Habitat improvement projects for moose should consider forage requirements and placement on the landscape in relation to cover and slope. © 2018 The Wildlife Society.

Survival and cause‐specific mortality of moose calves in Northeastern Minnesota

“…Generally, we observed mortalities to occur once females and their calves departed calving sites, consistent with other studies that reported calves were rarely killed at calving sites (Bubenik ). Previous studies have documented considerable variability in land cover types used by females for calving and during post‐parturition (Leptich and Gilbert , Addison et al , McGraw et al ) but have generally agreed that females tradeoff forage for predator avoidance (Bowyer et al , Testa et al 2000 b , Severud et al ). However, there is risk to either movement or remaining cryptic (Lima and Dill ).…”

Determining Timing of Births and Habitat Selection to Identify Lambing Period Habitat for Bighorn Sheep

“…Female ungulates select birth sites and habitat for nursery groups (i.e., females with young) based on a variety of trade-offs (Bowyer, 1991;Bowyer, 1991, 1994). These tradeoffs include predation risk, exposure to extreme weather, and forage quality and availability for the mother to fulfill nutritional requirements during late gestation and lactation (Festa-Bianchet, 1988b;Berger, 1991;Severud et al, 2019). For example, female bighorn sheep often return to the same general area each year to give birth (Geist, 1971;Etchberger and Krausman, 1999;Whiting et al, 2012).…”

“…Conversely, desert bighorn sheep (O. c. nelsoni) give birth in almost any month, ostensibly because of a less predictable growing season (Bunnell, 1982;Thompson and Turner, 1982;Rubin et al, 2000). Delineation of birthing habitat has important implications for the conservation, reproductive biology, and perpetuation of bighorn populations (Etchberger and Krausman, 1999;Wiedmann and Sargeant, 2014;Smith et al, 2015), and is a topic that is receiving increased attention for land-use planning (Severud et al, 2019).…”

“…Biologists can reduce and mitigate disturbance from anthropogenic activities to female ungulates during birthing by identifying when and where animals give birth (Dzialak et al, 2011;Kaze et al, 2016;McLaren et al, 2017). Determining timing of parturition in ungulates to identify high probability nursery areas can help managers mitigate temporal and spatial conflicts (Kaze et al, 2016;McLaren et al, 2017), and guide habitat management (Severud et al, 2019). Global positioning system (GPS) data can effectively document such patterns at fine scales (Longshore et al, 2013), especially for parturient females (Smith et al, 2015;McLaren et al, 2017;Severud et al, 2019).…”

“…Determining timing of parturition in ungulates to identify high probability nursery areas can help managers mitigate temporal and spatial conflicts (Kaze et al, 2016;McLaren et al, 2017), and guide habitat management (Severud et al, 2019). Global positioning system (GPS) data can effectively document such patterns at fine scales (Longshore et al, 2013), especially for parturient females (Smith et al, 2015;McLaren et al, 2017;Severud et al, 2019). We calculated timing of births to delineate habitat for nursery groups of GPS-collared desert bighorn sheep and Rocky Mountain bighorn sheep in two of the largest populations of those subspecies in Utah, United States.…”