Factors affecting the spatiotemporal distribution of moose, with a special emphasis on supplementary feeding

Doktorgradsavhandling ved Universitetet i Oslo ved det matematisk- naturvitenskapelige fakultet, nr 1016.Large herbivores constitute an important natural resource and are actively managed to meet economic, conservation and environmental objectives. To alleviate the potential of resource limitation and damage to commercially important habitats in areas with high population densities, the provisioning of artificial or supplementary forage has become a popular wildlife management intervention throughout Europe and North America. However, the usefulness of supplementary feeding is equivocal and little is known about how it affects spatiotemporal distribution patterns of large herbivores. The main aim of this thesis is to quantify the effect of supplementary feeding on the spatiotemporal distribution of moose (Alces alces L. 1758) living in southern Norway. I used locations of free-ranging GPS (global positioning system) collared moose (N = 26 in summer and N = 32 in winter) with access to supplementary feeding stations to estimate habitat selection and home range size as a function of feeding status (i.e. feeding station users vs. non-users), variation in browse quantity and quality, and also in terms of local climate and individual characteristics. To evaluate fine-scale distribution patterns and foraging decisions around supplementary feeding stations I employed 2 independent datasets (GPS data and browsing estimates) from two study areas (in Telemark and Hedmark counties) that differ in the length of their feeding history. I apply central-place foraging theory to explain the observed patterns. My results indicate that supplementary feeding affects the spatiotemporal distribution of moose only at intermediate to fine spatial scales during winter, with feeding station users behaving as central-place foragers. However, feeding station users did not differ in their large-scale habitat selection patterns or home range size compared to non-users. Instead, moose habitat selection was driven by a scale-dependent trade-off between browse quantity (landscape-scale) and browse quality (within-home rangescale). Moreover, depletion of high quality browse during winter lead moose to increase selection for lower quality browse within their home range. Variation in home range size was affected by several extrinsic (i.e. climate and natural browse) and intrinsic variables (i.e. individual characteristics) and their effects varied between and within spatiotemporal scales. After 6 years of feeding, moose that used feeding stations selected for commercially valuable browse (i.e. Scots pine) within their home range to the same extent as non-users, which questions the effectiveness of winter feeding in reducing browsing pressure over large spatial scales. In addition, as the time scale of feeding increased from 5-10 to 15-20 years, browsing pressure on commercially valuable browse (i.e. Scots pine and Norway spruce) was amplified at a fine spatial scale. At the same time, resource depletion in the vicinity of feeding stations lead moose to forage at increasing distances from feeding stations and browsing damage occurred at least up to 1 km from feeding stations. These findings suggest that when supplementary feeding is practised over longer time scales (more than 20 years) there is the potential for a trade off to occur between the energetic cost of returning to the central-place (i.e. feeding station) and the energetic benefits it provides. Evaluating management actions is important to determine whether the objectives and desired effects are realized. I have shown how supplementary feeding can affect the spatiotemporal distribution of moose and how subsequent browsing pressure around feeding stations can change over time. However, there are a variety of direct and indirect effects that follow the provisioning of supplementary forage that have not yet been adequately assessed. A holistic evaluation of the effectiveness of supplementary feeding as a wildlife management tool is required and needs to consider all the associated benefits and costs, especially considering long-term developments and potential ecosystem-level effects

Temperature-mediated habitat use and selection by a heat-sensitive northern ungulate.

This is the postprint version of the article. The published version can be located on the publisher's webpageWhile the behavioural response of animals to unfavourable climatic conditions has received increased attention recently, most habitat selection studies nonetheless ignore effects of ambient temperature. Thermoregulatory behaviour in endotherms should be most notable in species susceptible to heat stress. We evaluated whether a heat-sensitive northern ungulate, the moose (Alces alces), showed thermoregulatory behaviour in response to ambient temperature in two populations in southern Norway. We quantified the seasonal habitat use of GPS-collared adult females, as well as fine-scale habitat selection patterns, in relation to time of day and critical temperature thresholds thought to induce heat stress. We also assessed whether temperature driven changes in spatial behaviour led to a trade-off between thermal cover and forage availability. Frequent exposure to temperatures above critical thresholds occurred in both summer and winter and in both study areas. Moose responded by seeking thermal shelter in mature coniferous forest and avoiding open habitat types, leading to a trade-off between forage and cover availability in summer but not winter. Differences in habitat choice in response to temperature were most pronounced at twilight. We found that fine-scale habitat selection analyses, using step selection functions, more effectively revealed thermoregulatory behaviour in both seasons and populations than habitat use. This is because habitat selection analyses are better able to identify limiting factors operating at different spatiotemporal scales than habitat use. Future studies on thermoregulatory animal behaviour should focus on the effect of abiotic factors, such as climate, on habitat-fitness relationships, which may be critical to understanding population responses to a changing climate

Using habitat selection theories to predict the spatiotemporal distribution of migratory birds during stopover - a case study of pink-footed geese Anser brachyrhynchus

Th is study was part of MC ’ s PhD project funded by Aarhus University. Th e fi eldwork was supported by the Norwegian Research Council project MIGRAPOP.Understanding how animals select for habitat and foraging resources therein is a crucial component of basic and applied ecology. The selection process is typically influenced by a variety of environmental conditions including the spatial and temporal variation in the quantity and quality of food resources, predation or disturbance risks, and inter-and intraspecific competition. Indeed, some of the most commonly employed ecological theories used to describe how animals choose foraging sites are: nutrient intake maximisation, density-dependent habitat selection, central-place foraging, and predation risk effects. Even though these theories are not mutually exclusive, rarely are multiple theoretical models considered concomitantly to assess which theory, or combination thereof, best predicts observed changes in habitat selection over space and time. Here, we tested which of the above theories best-predicted habitat selection of Svalbard-breeding pink-footed geese at their main spring migration stopover site in mid-Norway by computing a series of resource selection functions (RSFs) and their predictive ability (k-fold cross validation scores). At this stopover site geese fuel intensively as a preparation for breeding and further migration. We found that the predation risk model and a combination of the density-dependent and central-place foraging models best-predicted habitat selection during stopover as geese selected for larger fields where predation risk is typically lower and selection for foraging sites changed as a function of both distance to the roost site (i.e. central-place) and changes in local density. In contrast to many other studies, the nutritional value of the available food resources did not appear to be a major limiting factor as geese used different food resources proportional to their availability. Our study shows that in an agricultural landscape where nutritional value of food resources is homogeneously high and resource availability changes rapidly; foraging behaviour of geese is largely a tradeoff between fast refuelling and disturbance/predator avoidance.Publisher PDFPeer reviewe

Invertebrate communities in adjacent Douglas fir and native beech forests in New Zealand

Non-native trees profoundly alter the structure and resilience of native forest ecosystems through direct or indirect effects on ecosystem processes, e.g. by altering invertebrate communities, but such effects are poorly understood in New Zealand. We sampled adjacent stands of the non-native tree Douglas fir (Pseudotsuga menziesii) and native beech (Nothofagaceae) forests and tested whether the overall invertebrate communities varied across forest types. We then assessed whether natural enemies, both trophic-generalist predators and more trophic-specialist parasitoids, differed across forest types. We found a trend for lower overall invertebrate family diversity in Douglas fir plantations compared to native beech forests. Parasitoid abundance was lower in Douglas fir forests compared to native beech forests, although we could not tease apart whether these effects were due to differences in forest age, forest type, or a combination of these factors. Our findings suggest that there are subtle shifts in invertebrate community composition from native forests to non-native forests, and that trophic specialisation might play a key role in determining which natural enemies can inhabit non-native forests in New Zealand. Nevertheless, our small sample size calls for further exploration of these patterns.Fil: Evans, Alison M.. Department Of Conservation; Nueva ZelandaFil: Peralta, Guadalupe. University of Canterbury; Nueva Zelanda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Provincia de Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Universidad Nacional de Cuyo. Instituto Argentino de Investigaciones de las Zonas Áridas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: van Beest, Floris M.. Department Of Conservation; Nueva ZelandaFil: Klijzing, Krista. Department Of Conservation; Nueva ZelandaFil: Peltzer, Duane. Crown Research Institutes. Landcare Research; Nueva Zeland

Effects of habitat selection & supplementary feeding on moose body weight & reproduction

Posteren ble presentert på 6th International Moose Symposium i Yakutsk, Russland 13-21 august 2008The effects of forage availability, winter supplementary feeding and habitat selection on moose body condition, reproductive rates and autumn slaughter weights are being studied in two locations in south-east Norway. GPS collared moose cows and their calves have been weighed and monitored in 2 years in the first study area and are currently being followed in the second study area. Preliminary results suggest that moose cows lose proportionally more weight over winter than calves and winter weight loss is lower in individuals using feeding stations, but only significantly so in the study area with a longer history of feeding and more severe winters. In the less snowy study area, cows using feeding stations only spent 30% of the winter within 500m of feeding stations and showed little difference in winter weight change or reproductive rate from individuals not using feeding stations. In the same study area, winter habitat selection differed slightly between users and non-users of feeding sites with users selecting less for spruce and deciduous stands. However, commercially important young pine stands were favoured by both groups of moose suggesting that supplementary feeding does not reduce forest damage. Moose using feeding sites concentrated space use around feeding stations, becoming central-place foragers. Data collection is on-going but we expect that the effects of supplementary feeding on habitat selection and ecological fitness will increase with the proportion of time spent at feeding stations, and hence be greater in severe winters and as the duration of the feeding programme increases

Reproductive success and failure: the role of winter body mass in reproductive allocation in Norwegian moose

This is the postprint version of the article. The original publication is available at www.springerlink.comA life-history strategy that favours somatic growth over reproduction is well known for long-lived iteroparous species, especially in unpredictable environments. Risk-sensitive female reproductive allocation can be achieved by a reduced reproductive effort at conception, or the subsequent adjustment of investment during gestation or lactation in response to unexpected environmental conditions or resource availability. We investigated the relative importance of reduced investment at conception compared with later in the reproductive cycle (i.e. prenatal, perinatal or neonatal mortality) in explaining reproductive failure in two high density populations in southern Norway. We followed 65 multiparous GPS-collared moose (Alces alces) throughout the reproductive cycle and focused on the role of maternal nutrition during gestation in determining reproductive success using a quasi-experimental approach to manipulate winter forage availability. Pregnancy rates in early winter were normal (≥0.8) in all years while spring calving rates ranged from 0.4 to 0.83, with prenatal mortality accounting for most of the difference. Further losses over summer reduced autumn recruitment rates to 0.23-0.69, despite negligible predation. Over-winter mass loss explained variation in both spring calving and autumn recruitment success better than absolute body mass in early or late winter. Although pregnancy was related to body mass in early winter, overall reproductive success was unrelated to pre-winter body condition. We therefore concluded that reproductive success was limited by winter nutritional conditions. However, we could not determine whether the observed reproductive allocation adjustment was a bet hedging strategy to maximise reproduction without compromising survival or whether females were simply unable to invest more resources in their offspring

Long-term effects of supplementary feeding of moose on browsing impact at a landscape scale

This is the author's version before it was send to the publisher. Therefore it can differ slightly from the published version. For the published version, please go to: http://www.sciencedirect.com/science/article/pii/S0378112713007925Supplementary feeding of wildlife is a common management practice, increasingly used to reduce or divert herbivore impact from sensitive habitats, forestry or agriculture. The landscape-scale spatial distribution of herbivory in relation to supplementary or diversionary feeding stations is of particular relevance to wildlife and land management, yet has never been quantified. We considered multiple hypotheses, based on central-place foraging theory, to investigate how landscape-scale browsing impact changed as a function of distance from feeding stations and thereby test the effectiveness of diversionary feeding. We assessed the landscape-scale browsing impact of moose by quantifying browsing patterns and moose density in commercially-valuable young Scots pine stands in an area of south-east Norway with a long history of winter feeding. We also used positions from GPS-collared female moose to investigate the spatial distribution of individuals across the landscape. Moose density and browsing impact at a fine spatial scale (<1km) followed an exponential decrease with distance from diversionary feeding stations. However, at a landscape scale (1-10 km), browsing impact did not show any relationship with distance to feeding stations. Leader stem browsing on Scots pine trees was high at both the local (< 1 km; 68 ± 12 %) and landscape (1- 10 km; 56 ± 7 %) scales. In addition, browsing on commercially valuable Norway spruce, which is normally avoided by moose, was locally high around feeding stations. As currently practiced, long-term diversionary feeding of moose was ineffective in diverting browsing impact from young pine stands at the landscape scale. Browsing on commercially-important tree species was sufficiently high that economic consequences could be expected. To avoid further conflict, we suggest a combination of reducing the moose density and increasing the availability of natural or more attractive supplementary forage