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

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

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

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

To feed or not to feed? Evidence of the intended and unintended effects of feeding wild ungulates

Ungulate populations are important natural resources, associated with both costs and benefits. Conflicts have arisen between stakeholders who benefit from high ungulate numbers and those faced with the costs. Supplementary or diversionary feeding may potentially mitigate conflicts while maintaining harvest yields but can have conservation implications. We quantified the empirical evidence for whether the intended effects, and hence management goals, of feeding are met. We also examined whether any potential unintended consequences of feeding occur and under what conditions. We found clear evidence that supplementary feeding enhanced reproduction and population growth under certain conditions. By contrast, we found limited evidence of the effectiveness of diversionary feeding to protect crops, forestry, and natural habitats, with positive effects often undermined by increases in ungulate density. However, the use of diversionary feeding to reduce traffic collisions seems promising but requires further investigation. The unintended effects of feeding are typically complex, involving changes to demography, behavior, and vegetation with consequent cascading effects on other trophic levels, as well as exacerbated risks of disease transmission. Increased ungulate density is the primary driver behind these unintended effects, the consequences of which tend to increase with longevity of feeding and affect a range of stakeholders. We urge managers to take seriously the risks as well as the economic and ethical issues before deciding to feed ungulate

Å fôra eller ikkje? Ei litteraturoversikt om fôring av storvilt

Ettersom storviltbestandane i Europa og Nord-Amerika har auka, ser folk ogso ulemper med tette bestandar. For å minska ulempene utan å redusera viltbestandane, har mange byrja å fôra. 2. Me har gått gjennom all tilgjengeleg litteratur for å sjå om forvaltarane nådde måla med fôringa og om fôringa hadde andre, ikkje planlagde fylgjer. 3. Me fann klare bevis for at fôring i periodar med lite anna fôr førde til større bestandar der kvart individ reproduserte betre. Haustvektene vart ikkje høgare ved fôring, haustvektene vart bestemt av sumarfôret. Me fann ikkje bevis for at forvaltarane klarte ved hjelp av fôring å trekkja beitinga bort frå innmark, ung furuskog eller andre attraktive matkjelder, truleg fordi det tilførde fôret ikkje tilfredsstilte nærings- og oppførselsbehova til viltet og fordi fôringa førde til tettare bestandar. Undersøkjingar viser at fôring har minska talet på påkøyrsler, men fleire undersøkjingar trengst for å få full visse. 4. Samling av mykje storvilt rundt fôringsplassar påverkar omgjevnadene. Effektane kan vera komplekse endringar i vegetasjonssamansetning og struktur. Dette kan påverka andre arter i systemet. Nokre sjukdomar vert lettare overførte når dyr samlar seg som rundt fôringsplassar. Ikkje planlagde fylgjer av fôring er lite studert, noko som gjer det vanskeleg å føreseia fylgjene. 5. Det er vanskeleg å rekna på økonomien for den einskilde jaktrettshavar då storviltbestandar gjerne kryssar eigedomsgrenser frå jakttid til fôringstid og ein ofte ikkje kjenner alle fylgjene. Fôringa fører gjerne til høgare og meir reproduktive bestandar og det kan vera vanskeleg å skilja negative verknader av det å fôra og det å ha tette bestandar. Tette bestandar kan ha langtidsverknader som folk kan oppfatta som bra eller dårlege. Før nokon set i gang større program med fôring av storvilt, bør dei grundig vurdera alle sider ved fôring og ha solid stønad frå grunneigarane i viltbestanden sitt heiltårsleveområde. Dersom dei vil slutta fôringa, må dei fyrst redusera viltbestanden. 6. Me har laga ei liste (kapittel 4.3) med punkt som forvaltarar bør gå gjennom og drøfta om dei vurderer å byrja fôra vilt.English: There are costs and benefits associated with large herbivore populations. As populations have grown, conflicts have arisen between stakeholders who benefit from high numbers and those faced with the costs. Feeding may potentially mitigate conflicts while maintaining harvest yields. 2. We created a series of hypotheses associated with the intended management goals of large herbivore feeding programmes and the commonly perceived unintended consequences. We quantified the empirical evidence in support of each hypothesis and established which factors determined the effectiveness of feeding and under what conditions unintended effects may occur. 3. We found clear and consistent evidence of demographic consequences of supplementary feeding. Reproduction and population size were enhanced in food-limited populations, where a high proportion of females had access to feed throughout the limiting season. By contrast, we found limited evidence of the effectiveness of diversionary feeding to protect crops, forestry and natural habitats, largely because any positive effects were undermined by high herbivore densities. The use of diversionary feeding to reduce traffic collisions requires further investigation. 4. Evidence indicates that unintended effects of feeding are likely when feeding causes aggregation and high densities, and when feed type does not match the foraging strategy of the target species. Unintended effects can be complex, involving habitat impacts, such as changes to vegetation composition and structure, with consequent cascading effects through the trophic levels. Disease transmission risks are also often increased. Unintended effects are generally less well studied, making clear predictions difficult. 5. The economic costs and benefits of feeding are typically borne by different stakeholder groups and may occur over different time-frames. Ethical views of feeding also vary between groups, ranging from obligation to undesirable step towards domestication. The risks of unintended consequences are likely to increase with longevity of feeding and should be considered at the outset. 6. We have written a list (chapter 4.3) with points that managers should discuss if they consider feeding wildlife

Population dynamics and spatial distribution of Griffon Vultures (Gyps fulvus

Summary The global decrease of vulture populations has been attributed to several factors, such as food availability, poisoning, human disturbance, or habitat suitability. We studied the effect of factors that vary both spatially and temporally on the nest site distribution of the Griffon Vulture Gyps fulvus in northeast Portugal, and influence the population dynamics of these cliff-dwelling birds. Several demographic parameters were studied in the field, and the age structure of the population was determined. Additionally we investigated how food availability affected population fluctuations. The vulture population was most sensitive to juvenile mortality according to our model results. Our models showed that a decrease in the present food supply resulted in a decrease in vulture abundance and, moreover, negatively affected the spatial distribution of the species by decreasing the number of breeding pairs per colony. The total quantity of sheep and goat biomass, a greater distance to the nearest unpaved road, and the presence of Egyptian Vultures Neophron percnopterus at the breeding colonies showed a significant positive relationship to the numbers of Griffon Vulture breeding pairs. It is recommended that the available food supply in the most important foraging areas should be monitored and protected. Furthermore, to manage the community of cliff breeding raptors adequately, future research should identify and protect the most suitable breeding areas for each species. Human disturbance should be kept to a minimum by protecting breeding areas, especially in an area like Riba-Cô a where species such as the Egyptian Vulture, Bonelli&apos;s Eagle Hieraaetus fasciatus and Griffon Vulture breed so close to each other

On the interplay between hypothermia and reproduction in a high arctic ungulate

For free-ranging animals living in seasonal environments, hypometabolism (lowered metabolic rate) and hypothermia (lowered body temperature) can be effective physiological strategies to conserve energy when forage resources are low. To what extent such strategies are adopted by large mammals living under extreme conditions, as those encountered in the high Arctic, is largely unknown, especially for species where the gestation period overlaps with the period of lowest resource availability (i.e. winter). Here we investigated for the first time the level to which high arctic muskoxen (Ovibos moschatus) adopt hypothermia and tested the hypothesis that individual plasticity in the use of hypothermia depends on reproductive status. We measured core body temperature over most of the gestation period in both free-ranging muskox females in Greenland and captive female muskoxen in Alaska. We found divergent overwintering strategies according to reproductive status, where pregnant females maintained stable body temperatures during winter, while non-pregnant females exhibited a temporary decrease in their winter body temperature. These results show that muskox females use hypothermia during periods of resource scarcity, but also that the use of this strategy may be limited to non-reproducing females. Our findings suggest a trade-of between metabolically driven energy conservation during winter and sustaining foetal growth, which may also apply to other large herbivores living in highly seasonal environments elsewhere.publishedVersio