A. David M. Latham

Movement responses by wolves to industrial linear features and their effect on woodland caribou in northeastern Alberta

Woodland caribou (Rangifer tarandus caribou) populations are declining across most of their range. Predation by wolves (Canis lupus) is believed to be the main proximate cause of these declines. However, it has been hypothesized that recent forestry and energy sector activity in caribou range ultimately might have caused population declines by altering wolf-caribou relationships. We tested the hypothesis that industrial linear features influence wolf movements in woodland caribou range in northeastern Alberta, resulting in increased wolf-caused caribou mortalities close to these features. Using step selection functions (SSF) and observed vs. simulated wolf movement paths, we found that wolf movement was influenced by natural linear features (rivers and streams) throughout the year, possibly because they provide ease of travel and high prey abundance. Wolf movement was further influenced by industrial linear features, but use of these features differed depending on line- type and season. Wolves showed strong selection for steps closer to conventional seismic lines during the snow-free season. Likewise, observed wolf movement paths followed conventional seismic lines more closely than simulated paths during snow-free months. Use of seismic lines as movement corridors might result in wolves hunting in caribou-preferred habitats (bogs and fens) more frequently than they did historically, particularly in the snow-free season when most caribou mortalities occur. However, we found no evidence that caribou mortalities occurred closer to industrial linear features than did live caribou. We conclude that wolf use of seismic lines increases predation risk for caribou close to these features, resulting in caribou avoidance of linear developments and thus functional loss of otherwise suitable habitat for caribou.

Invading White-Tailed Deer Change Wolf-Caribou Dynamics in Northeastern Alberta

ABSTRACT Human-caused habitat change has been implicated in current woodland caribou (Rangifer tarandus caribou) population declines across North America. Increased early seral habitat associated with industrial footprint can result in an increase in ungulate densities and subsequently those of their predator, wolves (Canis lupus). Higher wolf densities can result in increased encounters between wolves and caribou and consequently higher caribou mortality. We contrasted changes in moose (Alces alces) and deer (Odocoileus spp.) densities and assessed their effects on wolf-caribou dynamics in northeastern Alberta, Canada, pre (1994–1997) versus post (2005–2009) major industrial expansion in the region. Observable white-tailed deer (O. virginianus) increased 17.5-fold but moose remained unchanged. Wolf numbers also increased from approximately 6-11.5/1,000 km2 . Coincident with these changes, spatial overlap between wolf pack territories and caribou range was high relative to the mid-1990s. The high number of wolf locations in caribou range suggests that forays were not merely exploratory, but rather represented hunting forays and denning locations. Scat analysis indicated that wolf consumption of moose declined substantively during this time period, whereas use of deer increased markedly and deer replaced moose as the primary prey of wolves. Caribou increased 10-fold in the diet of wolves and caribou population trends in the region changed from stable to declining. Wolf use of beaver (Castor canadensis) increased since the mid-1990s. We suggest that recent declines in woodland caribou populations in the southerly extent of their range have occurred because high deer densities resulted in a numeric response by wolves and consequently higher incidental predation on caribou. Our results indicate that management actions to conserve caribou must now include deer in primary prey and wolf reduction programs.

Spatiotemporal interactions between wild boar and cattle: implications for cross-species disease transmission

Controlling infectious diseases at the wildlife/livestock interface is often difficult because the ecological processes driving transmission between wildlife reservoirs and sympatric livestock populations are poorly understood. Thus, assessing how animals use their environment and how this affects interspecific interactions is an important factor in determining the local risk for disease transmission and maintenance. We used data from concurrently monitored GPS-collared domestic cattle and wild boar (Sus scrofa) to assess spatiotemporal interactions and associated implications for bovine tuberculosis (TB) transmission in a complex ecological and epidemiological system, Doñana National Park (DNP, South Spain). We found that fine-scale spatial overlap of cattle and wild boar was seasonally high in some habitats. In general, spatial interactions between the two species were highest in the marsh-shrub ecotone and at permanent water sources, whereas shrub-woodlands and seasonal grass-marshlands were areas with lower predicted relative interactions. Wild boar and cattle generally used different resources during winter and spring in DNP. Conversely, limited differences in resource selection during summer and autumn, when food and water availability were limiting, resulted in negligible spatial segregation and thus probably high encounter rates. The spatial gradient in potential overlap between the two species across DNP corresponded well with the spatial variation in the observed incidence of TB in cattle and prevalence of TB in wild boar. We suggest that the marsh-shrub ecotone and permanent water sources act as important points of TB transmission in our system, particularly during summer and autumn. Targeted management actions are suggested to reduce potential interactions between cattle and wild boar in order to prevent disease transmission and design effective control strategies.

Spatial relationships of sympatric wolves (Canis lupus) and coyotes (C. latrans) with woodland caribou (Rangifer tarandus caribou) during the calving season in a human-modified boreal landscape

Abstract Context. Woodland caribou (Rangifer tarandus caribou) populations have declined across most of North America. Wolf (Canis lupus) predation on adults is partially responsible for declines; however, caribou declines also can be attributed to low calf survival. Wolves and invading coyotes (C. latrans) may contribute to mortality of calves. Aim. We assessed wolf and coyote food habits and population and individual level selection for caribou-preferred habitats (bogs and fens) during the caribou calving season (15 April to 30 June) in north-eastern Alberta, Canada, to determine what role these predators might play as a mortality factor for caribou calves. Methods. We deployed global positioning system and very high-frequency (VHF) radio-collars on 32 wolves and nine coyotes in January 2006 – January 2008, and VHF collars on 42 adult female caribou individuals in 2003–08. We assessed wolf and coyote habitat selection using used-available resource-selection functions, and spatial overlap of wolves and coyotes with caribou using logistic regression to estimate coefficients for latent selection-difference functions. We collected and analysed scats to assess wolf and coyote food habits. Key results. Wolves generally avoided caribou-preferred habitats, particularly bogs. Most coyotes selected caribou-preferred habitats (bogs and/or fens); however, relative to caribou, they were found closer to upland forests. Hair from adult and calf caribou was uncommon in wolf and coyote diet and caribou is likely to be an uncommon alternative prey for these predators. Conclusions. We found that >25% of wolf packs and most coyotes selected caribou-preferred habitats during the calving season. Although caribou was not an important prey, limited secondary predation, by these predators and black bears (Ursus americanus), on adult and calf caribou is likely to be contributing to caribou population declines. Implications. We caution that predation on caribou is likely to escalate as coyotes expand into this region and increasing human disturbance continues to create habitat for white-tailed deer (Odocoileus virginianus), which is an important prey for both wolves and coyotes.

Evaluation of camera traps for monitoring European rabbits before and after control operations in Otago, New Zealand

Abstract Context. European rabbits (Oryctolagus cuniculus) are reaching plague proportions again in some parts of New Zealand as the effect of rabbit haemorrhagic disease begins to wane. Effective monitoring techniques are required to quantify the success of alternative methods of controlling rabbits, such as poisoning. Aim. To evaluate camera traps as a method of estimating the percentage of rabbits killed in a poison control operation, and to compare results obtained from cameras with those from traditional monitoring methods (spotlight transects and vantage-point counts). Methods. We deployed cameras and conducted vantage-point counts and spotlight transects to compare a priori statistical power. We then used these monitoring methods to estimate percentage kill from a case study rabbit-control operation using sodium fluoroacetate (compound 1080). Key results. Cameras had good statistical power to detect large reductions in rabbit numbers (>90%) and the percentage kill estimated using cameras was comparable with spotlight transects and vantage-point counts. Conclusions. Cameras set up at fixed sampling locations can be an effective method of quantitatively assessing rabbit population control outcomes. We recommend that ≥6 cameras per 100 ha should remain active for at least 5 days before and 5 days following control, so as to obtain reliable estimates of percentage kill. Implications. Cameras may be preferable to conventional monitoring methods where there is insufficient area to walk or drive transects, terrain is too rugged or scrubby for transects, and there are no or few vantage points from which to count rabbits.

The ecology and management of mammal invasions in forests

Populations of invasive wild mammals have contributed significantly to the total unwanted impacts of biological invasions. They are known to impact forest ecosystems globally, but reviews summarizing this information are currently lacking. Here we (1) review the ecological characteristics of mammal invasions in forests; (2) characterize the range of ecological impacts on forest communities and the economic consequences of those impacts; (3) review what is known about interactions between the impacts of invasive mammals and other drivers of global change; and (4) consider the complex ecological and socio-economic challenges of simultaneously managing multiple invasive mammals and native biota affected by them. The unwanted impacts of invasive herbivores and predators are intensifying in many parts of the world and the need to manage their impacts to prevent further loss of indigenous biodiversity and damage to productive assets is greater than ever. However, management needs to be conducted within appropriate social, cultural, ethical, and animal welfare frameworks. Achieving effective management of populations of mammals invasive in forest ecosystems will require the filling of many knowledge gaps, including: better understanding their impacts; strategic options and tactical solutions for managing them; and achieving social licence to operate.

Seasonal and individual variation in selection by feral cats for areas with widespread primary prey and localised alternative prey

Abstract Context. Seasonal and individual variation in predator selection for primary and alternative prey can affect predator–prey dynamics, which can further influence invasive-predator impacts on rare prey. Aims. We evaluated individual and seasonal variation in resource selection by feral cats (Felis silvestris catus) for areas with European rabbits (Oryctolagus cuniculus) around a breeding colony of endangered black-fronted terns (Chlidonias albostriatus) in the Upper Ohau River, within the Mackenzie Basin of New Zealand. Methods. Within a feral cat population subject to localised control (within a 1-km area surrounding the tern colony), we mapped the movements of 17 individuals using GPS collars, and evaluated individual and seasonal variation in third-order resource selection (i.e. within home ranges) by using resource-selection functions with mixed effects. The year was divided into breeding and non-breeding seasons for terns. Key results. Three of the eight feral cats monitored during the breeding season used the colony in proportion to availability and one selected it. These four individuals therefore pose a threat to the tern colony despite ongoing predator control. Selection by feral cats for areas with high relative rabbit abundance was not ubiquitous year-round, despite previous research showing that rabbits are their primary prey in the Mackenzie Basin. Conclusions. Results suggest that rabbit control around the colony should reduce use by feral cats that select areas with high relative rabbit abundance (less than half the individuals monitored), but is unlikely to alleviate the impacts of those that select areas with low relative rabbit abundance. Hence, predator control is also required to target these individuals. Results thus support the current coupled-control of feral cats and rabbits within a 1-km buffer surrounding the tern colony. Future research should determine what scale of coupled-control yields the greatest benefits to localised prey, such as the tern colony, and whether rabbits aid hyperpredation of terns by feral cats via landscape supplementation. Implications. The present study has highlighted the importance of considering seasonal and individual effects in resource selection by predators, and the role of primary prey, when designing management programs to protect rare prey.

Assessing the efficacy of aerial culling of introduced wild deer in New Zealand with analytical decomposition of predation risk

Native and introduced wild deer have significant unwanted impacts in many countries. Lethal control, usually by hunting, is the most cost-effective method of reducing their number and impact. However, deer habitat use varies spatially and temporally, meaning that hunters (the predator) may search in habitats with few or no deer. Also, deer may modify their behaviour in response to hunting pressure in ways that decrease the risk of being killed, reducing the efficacy of lethal control programmes. To address these issues we decomposed the predation process into its four constituent stages–prey occurrence, predator search, predators encounter prey, predators kill prey they encounter–to reveal what makes female sika deer (Cervus nippon) in the North Island, New Zealand, more susceptible to control by professional helicopter-based hunters. Female sika deer were encountered more in some habitats or landscape features than in others, but the likelihood of kill given an encounter in those habitats was not always correspondingly high. Similarly, variables that positively influenced the probabilities of encounter and kill did not similarly influence deer occurrence, and variables most likely to be searched often poorly correlated with the other predation stages. These disparities contributed to suboptimal searching for and killing of deer by helicopter-based hunters during winter and spring, but not summer. Our study demonstrates how decomposing predation risk can identify risk and refuge areas for target species, and can be used to alter tactics as target species adjust to changing predation risk. This analytical approach is highly applicable to other human hunter–prey systems.

Interactions between dingoes and introduced wild ungulates: concepts, evidence and knowledge gaps

The dingo (Canis dingo or C. familiaris, including hybrids with feral dogs) is the apex carnivore on mainland Australia. Fifteen non-native ungulate species have established wild populations in Australia. Dingoes are managed to reduce impacts on domestic ungulates, and introduced wild ungulates are managed to reduce impacts on natural ecosystems and to minimise competition with domestic ungulates. There is speculation about the extent to which (1) dingoes limit the abundances of introduced wild ungulates, and (2) introduced wild ungulates sustain dingo populations. We reviewed the literature to identify potential ecological interactions between dingoes and introduced wild ungulates, and to synthesise evidence for interactions between dingoes and each ungulate species (including the percentage frequency occurrence (%FO) of ungulates in dingo diets). Eleven of the 15 ungulate species were recorded in the diet of dingoes, with the highest %FO occurrences reported for feral goats (73%) and cattle (60%). Two studies concluded that dingoes reduced ungulate abundances (feral goat (Capra hircus) and feral donkey (Equus asinus)), and two studies concluded that dingoes did not regulate feral pig (Sus scrofa) abundances. A fifth study concluded that dingoes exhibited a Type III functional response to increasing sambar deer (Cervus unicolor) abundances. A sixth study concluded that dingoes made relatively little use of hunter-shot sambar deer carcasses. We propose that interactions between dingoes and introduced wild ungulates depend on the sex–age classes vulnerable to dingo predation, dingo pack sizes, the availability of escape terrain for ungulates and the availability of alternative foods for dingoes. The interplay between environmental conditions and the population growth rate of ungulates, and hence their ability to sustain losses from predation, could also be important. We predict that dingoes will have most impact on the abundance of smaller ungulate species and neonates.

Habitat use of Himalayan grey goral in relation to livestock grazing in Machiara National Park, Pakistan

Abstract The Himalayan grey goral (Naemorhedus goral bedfordi) occurs in Pakistan and India, and is classified as Near Threatened on The IUCN Red List. This subspecies is threatened primarily by illegal hunting and competition with livestock, resulting in small and fragmented populations. The present study provides information on habitat use by grey goral at two locations in Machiara National Park (MNP), Azad Jammu and Kashmir, Pakistan, from 2012 to 2013. One location had low grazing pressure from livestock (Machiara), whereas the other had intensive livestock grazing (Serli Sacha). We determined the distribution of grey goral through direct observations of the animals and by the presence of their faecal pellets. We assessed habitat preferences using Ivlev’s electivity index (IEI) by comparing vegetation and topography at used and unused quadrats along nine monitoring lines. Grey gorals strongly avoided areas with high livestock numbers, particularly grazers (cattle Bos taurus and sheep Ovis aries). Grey gorals were most commonly observed on south-facing slopes between 1970 and 2900 m a.s.l. during all seasons. Grey gorals preferred herbs and grasses (IEI=0.14), used shrubby vegetation in proportion to its availability (IEI=0.03), and avoided densely treed areas (IEI=-0.54). Our study suggests that a comprehensive livestock grazing strategy needs to be developed for the conservation of habitat suitable for grey goral in MNP.