Effects of predator treatments, individual traits, and environment on moose survival in Alaska

Abstract

We studied moose (Alces alces) survival, physical condition, and abundance in a 3-predator system in western Interior Alaska, USA, during 2001USA, during -2007 Our objective was to quantify the effects of predator treatments on moose population dynamics by investigating changes in survival while evaluating the contribution of potentially confounding covariates. In May 2003 and 2004, we reduced black bear (Ursus americanus) and brown bear (U. arctos) numbers by translocating bears !240 km from the study area. Aircraft-assisted take reduced wolf (Canis lupus) numbers markedly in the study area during 2004-2007. We estimated black bears were reduced by approximately 96% by June 2004 and recovered to within 27% of untreated numbers by May 2007. Brown bears were reduced approximately 50% by June 2004. Late-winter wolf numbers were reduced by 75% by 2005 and likely remained at these levels through 2007. In addition to predator treatments, moose hunting closures during 2004-2007 reduced harvests of male moose by 60% in the study area. Predator treatments resulted in increased calf survival rates during summer (primarily from reduced black bear predation) and autumn (primarily from reduced wolf predation). Predator treatments had little influence on survival of moose calves during winter; instead, calf survival was influenced by snow depth and possibly temperature. Increased survival of moose calves during summer and autumn combined with relatively constant winter survival in most years led to a corresponding increase in annual survival of calves following predator treatments. Nonpredation mortalities of calves increased following predator treatments; however, this increase provided little compensation to the decrease in predation mortalities resulting from treatments. Thus, predator-induced calf mortality was primarily additive. Summer survival of moose calves was positively related to calf mass (b > 0.07, SE ¼ 0.073) during treated years and lower (b ¼ À0.82, SE ¼ 0.247) for twins than singletons during all years. Following predator treatments, survival of yearling moose increased 8.7% for females and 21.4% for males during summer and 2.2% for females and 15.6% for males during autumn. Annual survival of adult (!2 yr old) female moose also increased in treated years and was negatively (b ¼ À0.21, SE ¼ 0.078) related to age. Moose density increased 45%, from 0.38 moose/ km 2 in 2001 to 0.55 moose/km 2 in 2007, which resulted from annual increases in overall survival of moose, not increases in reproductive rates. Indices of nutritional status remained constant throughout our study despite increased moose density. This information can be used by wildlife managers and policymakers to better understand the outcomes of predator treatments in Alaska and similar environments. ß 2011 The Wildlife Society.

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

“…If forage availability is associated with less movement (Saïd and Servanty ), detection by predators may be reduced. This increase in nutrition may have facilitated a higher quantity and quality of milk and an increased ability of the female to protect its calf from predators because moose that are nutritionally stressed defend calves less vigorously (Oftedal , Keech et al , Patterson et al ). A possible alternate explanation is that predators differentially use land cover types during this time of year and were less likely to use deciduous forest (Hebblewhite et al , Bastille‐Rousseau et al , DeCesare ).…”

The Role of Economic and Social Factors Driving Predator Control in Small-Game Estates in Central Spain

“…On the one hand, the consumption of small-game species by predators is usually low (e.g., Díaz-Ruíz et al 2013), and, on the other hand, other sources of mortalities may be more important than predation. For example, in Alaska predator-induced moose (Alces alces) calf winter mortality was proportionally much lower than that attributable to other causes, such as snow depth and temperature (Keech et al 2011). Similarly, in central Spain, agricultural practices, and not predation, appear to be the main cause of nest failure in red-legged partridge (Casas and Viñuela 2010).…”

“…This is mainly because causes of conflict are often complex http://www.ecologyandsociety.org/vol18/iss2/art28/ and some are rarely considered in conflict studies. Thus, although human-predator conflicts are generally embedded into an ecological, economic, and social context ( Fig.1; White et al 2009), most studies performed to date focus only on ecological aspects (e.g., Keech et al 2011). For example, there have been many ecological studies aiming to assess predator control effectiveness in reducing livestock or game bag losses; these have produced various results, suggesting that predator control effectiveness is highly context dependent (reviewed in Smith et al 2010).…”

Prey Selection of Scandinavian Wolves: Single Large or Several Small?

“…Hence, the nutritional status of individuals may have the potential to affect prey selection. In seasonally variable regions predator selection of prey may also be affected by weather-induced effects on prey vulnerability which may change as winter proceeds [12, 28, 29, 30, 31]. …”