Habitat Selection by American Martens in Coastal California

ABSTRACT We investigated habitat selection using single- and mixed-scale modeling at 2 spatial scales, stand and home range, by the only known population of American martens (Martes americana) remaining in the historical range of the Humboldt subspecies (M. a. humboldtensis) in California, USA. During 2000 and 2001, we sampled a 12 times 14 grid with 2-km spacing, using 2 sooted track plates at each grid point. We detected martens at 26 of the 159 grid points. We used resource selection probability functions and an information-theoretic method to model habitat at detection locations. At the stand scale, martens selected conifer-dominated stands with dense, spatially extensive shrub cover (x̄ = 74% cover, SE = 4) in the oldest developmental stage. At the home-range scale, martens selected the largest available patches (x̄ = 181 ha, SE = 14) of old-growth, old-growth and late-mature, or serpentine habitat. Mixed-scale models revealed that habitat characteristics from both scales best explained marten occurrence compared to one scale alone. Dense, spatially extensive shrub cover is a key habitat element for martens in coastal forests. Dense shrubs provide refuge from predators, cover for prey, and may also deter larger-bodied competitors. Managers can increase the likelihood of marten population persistence and encourage expansion in coastal forests by maintaining and restoring late-mature and old-growth, conifer-dominated forests with dense shrub cover in large, contiguous patches.     

Habitat characteristics of Eurasian pine martens Martes martes in an insular Mediterranean environment

Eurasian pine martens are considered habitat specialists, associated primarily with mature stands of mesic mixed wood forest habitats, and avoid areas without overhead cover The species is found throughout the temperate and boreal regions of the continent but on the Mediterranean island of Minorca, introduced pine martens thrive in a competitor- and predator-free environment I test the prediction that because of evolved prey-capture and predator avoidance strategies Minorcan martens should select habitats most similar to temperate and northern parts of their range Scat index routes were used to quantify pine marten habitat selection Marten did not demonstrate any habitat type preferences although observed use of pine forests and coastal shrublands was slighly greater than expected Marten were indifferent to overhead cover whereas mesic sites and areas of tall high shrub density were favored Small mammal trap indices and preferred prey suggested that martens commonly used non-forested areas My results demonstrated that on Minorca pine martens were habitat generalists In the absence of predators open non-forested habitats were equally important to pine marten as were forested ones     

Diurnal Habitat Relationships of Canada Lynx in an Intensively Managed Private Forest Landscape in Northern Maine

Abstract In March 2000, Canada lynx (Lynx canadensis) were listed as a federally threatened species in 14 states at the southern periphery of their range, where lynx habitat is disjunct and snowshoe hare (Lepus americanus) densities are low. Forest conditions vary across lynx range; thus, region-specific data on the habitat requirements of lynx are needed. We studied lynx in northern Maine, USA, from 1999 to 2004 to assess quality and potential for forests in Maine to sustain lynx populations. We trapped and radiocollared 43 lynx (21 M, 22 F) during this period and evaluated diurnal habitat selection by 16 resident adult lynx (9 M, 7 F) monitored in 2002. We evaluated lynx selection of 8 habitats at multiple spatial scales, and related lynx habitat selection to snowshoe hare abundance. Lynx preferred conifer-dominated sapling stands, which supported the highest hare densities on our study site (x̄ = 2.4 hares/ha), over all other habitats. The habitats where lynx placed their home ranges did not differ by sex. However, within their home ranges, males not only preferred conifer-dominated sapling stands, but also preferred mature conifer, whereas females singularly preferred conifer-dominated sapling stands. Approximately one-third of Maine's spruce-fir forest and nearly 50% of our study area was regenerating conifer or mixed-sapling forest, resulting from a disease event and intensive forest management (e.g., large clear-cuts). Our findings suggest that current habitat conditions in Maine are better than western montane regions and approach conditions in boreal forests during periods of hare abundance. We recommend that forest landowners maintain a mosaic of different-aged conifer stands to ensure a component of regenerating conifer-dominated forest on the landscape.     

Habitat,Climate, and Fisher and Marten Distributions

Since the mid-twentieth century, fisher populations (Pekania pennanti) increased in several eastern jurisdictions of North America, particularly in the northern part of the species’ range. Changes in fisher distribution have led to increased overlap with the southern portion of the range of American marten (Martes americana), whose populations may be locally declining. This overlap occurs particularly in habitats undergoing natural and anthropogenic modification. The objective of our study was to determine the respective effects of habitat changes and climatic conditions on fisher and marten populations in Quebec, Canada, based on trapper knowledge. We analyzed annual fisher and marten harvest (number of pelts sold/100 km²) between the 1984–1985 and 2014–2015 trapping seasons using linear mixed models. Fisher harvest increased with the increased abundance of mixed forests >12 m tall, resulting from decades of forest harvesting. Fisher harvest decreased with increasing spring rains, which can affect survival when rearing young. Marten harvest decreased with increasing winter rains, which lower thermoregulation capacity and hamper movements by creating an ice crust on the snowpack, reducing access to subnivean areas. Decline in marten harvest during the 30-year study period coincided with an increase in fisher harvest, suggesting possible interspecific competition. Results highlight that managers should strive to maintain mixedwood stands taller than 12 m to maintain high quality habitat for fishers. Our study confirms the importance of working with trappers to assess furbearing population trends in response to habitat changes and climatic conditions. © 2019 The Wildlife Society.     

Habitat selection of European pine marten in Central Italy: from a tree dependent to a generalist species

Studies at small spatial scale are often fundamental to highlight the behavioural plasticity of a species and thus have important implications for conservation planning, in particular for species usually considered as habitat specialists. We investigated second-order habitat selection of the European pine marten in an area dominated by deciduous oak forest and open fields in central Italy, by radio-tracking 16 pine martens (eight males, eight females). Pine martens placed home ranges in areas with more open field than in the study area, whereas woodland (oak and conifer forests) comprised a smaller portion of the home range than predominant forest character of the studied area. Although the presence of the species in the open habitats has been documented, to our knowledge, our results provide the first evidence of home range establishment in this cover type by pine marten at population level. The combination of low predation risk and high availability of resources could allow pine martens to occupy open fields in our study area. We highlighted different individual strategies of habitat selection, with some individuals placing home ranges in areas with high forest coverage while others occupying open areas. We found no effects of sex and body condition on habitat selection, and this could indicate that in the study area, both forested and non-forested cover types, such as open fields, shrub and anthropic areas, can provide adequate food, overhead cover and resting sites for all individuals. Pine marten ability to occupy open fields seems thus more related to the behavioural flexibility of the species, rather than to the need to supplement dens and forage from complementary lower quality habitat. The high quality of the Mediterranean continental area studied could also explain the selection of open areas by the pine marten. Our results offer useful information on pine marten ecology and may be helpful for conservation management of this species in southern Europe.     

Spatial organisation and dynamics of the pine marten Martes martes population in Białowieza Forest (E Poland) compared with other European woodlands

We studied factors affecting density and spacing patterns in the pine marten Martes martes population inhabiting temperate forests of Bia?owieza National Park, eastern Poland. From 1985/1986 to 1995/1996 marten densities ranged from 3.63 to 7.57 individuals 10 km^?2 (mean 5.4) and were positively correlated with abundance of forest rodents in the previous year. The rate of marten population growth was inversely density‐dependent and positively related to rodent density. Annual mortality rate averaged 0.384 and tended to be negatively related to marten densities. Mean annual home range of males (2.58 km², SE=0.24) was larger than that of females (1.41 km², SE=0.20). Seasonal home ranges also differed significantly between males and females. Both sexes held the smallest ranges in December–January. Female ranges increased in April–May, whereas those of males increased in June–September when they were mating. Fidelity of pine martens to their home ranges was very high. The mean shift between arithmetic centres of seasonal ranges was 0.25 km, and the ranges recorded in two consecutive seasons overlapped, on average, by 87–90%. We observed very little home range overlap between neighbouring male (mean 4–6%) or female (mean 6%) marten. Year round the neighbouring individuals of the same sex neither avoided nor attracted each other. Females attracted males only during the spring‐summer mating season. A review of other studies has documented that winter severity and seasonal variation in ecosystem productivity were essential factors shaping the biogeographic variation in pine marten densities between 41^o and 68^oN. The density of marten populations increased in areas with mild winters and lower seasonality. Maximum population densities (indicative of habitat carrying capacity) were correlated with mean winter temperature. In Europe, male home ranges increased with decreasing forest cover in a study area, whereas female ranges varied positively with rodent abundance.     

Decline in American marten occupancy rates at Sagehen Experimental Forest,California

We compared the distribution and frequency of American marten (Martes americana) detections during historic surveys and a recent survey on the Sagehen Experimental Forest (SEF) in the Sierra Nevada Mountains, California. This area has been the location of 9 previous marten surveys during 1980–1993, each involving a systematic detection/non-detection survey on the same grid. These data are a time series of information on the occupancy of martens that can be related to habitat change in the study area. Our objectives were to 1) resurvey martens in SEF using methodology similar to previous studies to assess current marten occupancy; 2) evaluate changes in marten occupancy during the period 1980–2008; and 3) examine associations between marten occurence and changes in habitat and landscape metrics. Current marten occupancy was estimated using surveys conducted in summer 2007, winter 2007–2008, and summer 2008. From 1978 to 2007 there was a decrease in predicted habitat patch size, core area, and total amount of marten habitat in the study area, as well as an increase in distance between patches. Marten detections in 2007–2008 were approximately 60% lower than in surveys in the 1980s. We detected no martens in the summers of 2007 and 2008, and 10 detections in winter 2007–2008 were limited to higher elevations in the southwestern portion of SEF. No martens were detected in the lower elevations where most of the recent forest management activity occurred. We suggest that the marten population at SEF has been negatively affected by the loss and fragmentation of habitat. We recommend that future management of forests in the Sagehen basin focus on restoring and connecting residual marten habitat to improve habitat quality for martens. © 2011 The Wildlife Society.     

Carbon pools in a boreal mixedwood logging chronosequence

Mixedwood forests are an ecologically and economically important forest type in central Canada, but the ecology of these forests is not as well studied as that of single-species dominated stands in the boreal forest. Northern boreal mixedwood forests have only recently been harvested and the effects of harvesting on carbon content in these stands are unknown. We quantified the carbon content and aboveground net primary production (NPP) for four different-aged mixedwood boreal forest stands in northern Manitoba, Canada. The stands included 11-, 18-, and 30-year-old stands that originated from harvesting and a 65-year-old fire-originated stand that typifies the origin of all northern boreal mixed-wood forests that are coming under management. Trees included black spruce (Picea mariana (Mill.) B.S.P.), jack pine (Pinus banksiana Lamb.), balsam poplar (Populus balsamifera L.), and quaking aspen (Populus tremuloides Michx.). Overstory biomass was estimated using species-specific allometric models that generally explained greater than 95% of the observed variation in biomass. Carbon content of the overstory vegetation was greatest in the 65-year-old stand and was 74% larger than the 11-year-old stand and showed a positive relationship with stand age (F_{1, 2}=122.62, P=0.0081 R²=0.99). The slope of mineral soil carbon did not differ significantly among stands (F_{1, 2}=0.39, P=0.5956, R²=0.16). Coarse woody debris carbon content followed a U-shaped pattern among stands. Aboveground NPP differed by 24% between the youngest and oldest stand. Mean annual carbon accumulation and aboveground NPP rates of the mixedwood forests were on average two times greater than nearby relatively pure stands studied during the BOREAS (BOReal Ecosystem Atmospheric Study) project. The trends in the results, along with other field studies, suggest that harvesting does not significantly affect the total soil carbon content. The results of this study suggest that scientists should be cautious about extrapolating results from BOREAS stands to a broader region until more data on other forest types and regions are available.     

Habitat selection by capercaillie in summer and autumn: Is bilberry important?

The use of habitat by female and male adult capercaillie Tetrao urogallus during summer and autumn was studied by comparing the distribution of radio locations of birds with the availability of habitat at forest stand, home range and landscape level in an area of the Bavarian Alps, Germany. Capercaillie preferred forests with structural features typical of their main distribution range, the boreal forest: they selected large patches of old forest with moderate canopy cover of about 50%, and a well developed field layer with high proportions of bilberry Vaccinium myrtillus. Hens selected both home ranges and sites within home ranges in old forest. Ranges selected by cocks did not differ from availability in the study area, but they preferred old forest within their ranges. The size of home ranges was negatively related to bilberry cover both in hens and cocks. The distribution of bilberry also determined habitat use by capercaillie at the landscape scale. The study demonstrated that bilberry is the major determinant of the selection of habitat by capercaillie in landscapes with sparse and fragmentary cover of ericaceous shrubs, such as central Europe.     

The influence of forest fragmentation and landscape pattern on American martens

1. We investigated the effects of forest fragmentation on American martens ( Martes americana Rhoads) by evaluating differences in marten capture rates (excluding recaptures) in 18 study sites with different levels of fragmentation resulting from timber harvest clearcuts and natural openings. We focused on low levels of fragmentation, where forest connectivity was maintained and non-forest cover ranged from 2% to 42%.
2. Martens appeared to respond negatively to low levels of habitat fragmentation, based on the significant decrease in capture rates within the series of increasingly fragmented landscapes. Martens were nearly absent from landscapes having > 25% non-forest cover, even though forest connectivity was still present.
3. Marten capture rates were negatively correlated with increasing proximity of open areas and increasing extent of high-contrast edges. Forested landscapes appeared unsuitable for martens when the average nearest-neighbour distance between open (non-forested) patches was <100 m. In these landscapes, the proximity of open areas created strips of forest edge and eliminated nearly all forest interior.
4. Small mammal densities were significantly higher in clearcuts than in forests, but marten captures were not correlated with prey abundance or biomass associated with clearcuts.
5. Conservation efforts for the marten must consider not only the structural aspects of mature forests, but the landscape pattern in which the forest occurs. We recommend that the combination of timber harvests and natural openings comprise <25% of landscapes ≥9 km² in size.
6. The spatial pattern of open areas is important as well, because small, dispersed openings result in less forest interior habitat than one large opening at the same percentage of fragmentation. Progressive cutting from a single patch would retain the largest amount of interior forest habitat.     

Patch occupancy by stone martens Martes foina in fragmented landscapes of central Spain: the role of fragment size,isolation and habitat structure

We studied the response to forest fragmentation of a generalist carnivore, the stone marten Martes foina, in highly fragmented landscapes of central Spain. Five different areas (n = 178 fragments) in central Spain were surveyed. This paper analyses the relationship between fragment use by martens (measured through scat presence) and a series of variables related to the size, isolation and vegetation structure of each fragment by means of stepwise logistic regression. Size and isolation have an important effect on stone marten presence in fragments. Our results were similar to those found for other marten species in landscapes with coarse-grain fragmentation, but they contrast with other studies conducted in landscapes with fine-grain fragmentation. These data suggested that in highly fragmented landscapes, size and isolation factors resulting from forest fragmentation were responsible for determining marten responses, irrespective of their habitat generalism. Management policies for the stone marten in highly fragmented scenarios require the maintenance of large forests near continuous forest tracts in mountains or riparian woodlands.     

Space and habitat use of moose in southwestern Sweden

Increasingly, wildlife managers and land managers are challenged to maintain the viability of large mammal populations. Although the moose (Alces alces) is an ecologically, economically, and culturally important ungulate species found throughout most of Sweden, little is known about its ecology throughout the southern part of the country. We collected baseline ecological data on spatial and habitat use patterns in urbanized southwestern Sweden by fitting 22 adult moose (13 F, nine M) with global positioning system (GPS) radio collars. Home range size of cows did not differ among seasons (P > 0.10); however, bulls had larger home ranges during fall than all other seasons (P < 0.010). Mean home range size of males during fall and spring was larger than females during any season (P < 0.010). We used a Euclidean distance-based approach to analyze multi-scale habitat selection by moose. Moose of both sexes and during all seasons selected boreal forest and mires when establishing a home range (P < 0.10). Moose had seasonal differences in habitat selection within their home range (P 0.001), and generally selected clear-cuts and early successional forests, mature coniferous forests, and glades, but avoided agricultural areas and open water. Habitat and space use characteristics of moose in our urbanizing study area were similar to characteristics reported for moose in forest-dominated landscapes of Fennoscandia.     

Landscape Use by Hairy Woodpeckers in Managed Forests of Northwestern Washington

ABSTRACT The hairy woodpecker (Picoides villosus) is a keystone species in forest ecosystems of Washington, USA, providing nesting and roosting cavities for many species of wildlife. Therefore, management practices that promote healthy populations of this bird will help to conserve cavity-nesting communities as a whole. The objective of this study was to determine patterns in forest type and landscape use by hairy woodpeckers, and thus, provide landscape-level recommendations to forest managers. We documented the ranging patterns and habitat use of 23 hairy woodpeckers on the Olympic Peninsula using radiotelemetry and a Geographic Information System analysis. Use patterns of stand age, type, and size, as well as distance-from-edge analyses revealed that the hairy woodpecker is a relative generalist in its use of the managed forest landscape. However, certain features, such as older stands with large trees, were used more heavily by nesting pairs. Hairy woodpeckers used 61–80-year forest stands significantly (P < 0.05) more than expected relative to their availability within the birds' home ranges. We also documented significant underuse of 6–10-year and 11–20-year stands, whereas the birds used 41–60-year stands, >80-year stands, and clear-cuts (< 5 yr) equivalent to their availability. We suggest that hairy woodpeckers select older stands with larger, dying trees for foraging, but also use clear-cuts proportionally due to the residual snags, decaying trees, and remnant dead wood available. Higher use (P < 0.001) by hairy woodpeckers of small forest patches (0–5 ha) and intermediate-sized stands (5–30 ha) than large patches (>30 ha) may be a result of the older, higher-quality habitat available in small stands in the managed forest landscape. We recommend that land managers interested in maintaining healthy managed forest ecosystems with a full complement of cavity-using species in forests of western Washington and northwestern Oregon maintain a landscape mosaic with approximately 45% of the landscape in stands >40 years, and >30% of the landscape in stands >60 years.     

Home range size of willow tits: a response to winter habitat loss

We examined the behavioral response to habitat loss and fragmentation of willow tits (Parus montanus) in winter in a mosaic forest landscape in northern Finland. We studied habitat preference, flock size and home range size of 16 flocks, half of which had their territories in forests fragmented by forestry and half in continuous forest. We predicted that birds would respond to habitat loss by enlarging their home range and/or diminishing group size. In addition, to compensate for fragmentation effects, willow tits might be expected to include more optimal habitat into their territories. Flocks included on average 3.9 birds and occupied territories of 12.6 ha. Willow tits avoided open areas (clear cuts and young sapling stands) and preferred mature forests and older sapling stands or pine bogs equally. Birds responded to habitat loss by enlarging their home ranges but not by reducing the group size. Large territories included a smaller proportion of mature forests, but the proportion of sapling and pine bog habitat did not change. Birds on territories that included a large proportion of open habitat localized their activity on several distinct habitat patches that were distributed over a wide area. We conclude that willow tits adjust territory use to compensate for the inclusion of unsuitable habitat within home ranges, and older sapling areas and pine bogs serve as surrogates for mature forests. However, birds did not enlarge the proportion of forest habitat in their territories with increasing habitat loss. Thus, our data do not suggest a strong effect of fragmentation, but imply that forestry practices reduce suitable wintering habitat and carrying capacity in the area. Thus winter habitat loss may explain the observed population decline of willow tits in Finland during recent decades.     

Positive edge effects on forest-interior cryptogams in clear-cuts

Biological edge effects are often assessed in high quality focal habitats that are negatively influenced by human-modified low quality matrix habitats. A deeper understanding of the possibilities for positive edge effects in matrix habitats bordering focal habitats (e.g. spillover effects) is, however, essential for enhancing landscape-level resilience to human alterations. We surveyed epixylic (dead wood inhabiting) forest-interior cryptogams (lichens, bryophytes, and fungi) associated with mature old-growth forests in 30 young managed Swedish boreal forest stands bordering a mature forest of high conservation value. In each young stand we registered species occurrences on coarse dead wood in transects 0-50 m from the border between stand types. We quantified the effect of distance from the mature forest on the occurrence of forest-interior species in the young stands, while accounting for local environment and propagule sources. For comparison we also surveyed epixylic open-habitat (associated with open forests) and generalist cryptogams. Species composition of epixylic cryptogams in young stands differed with distance from the mature forest: the frequency of occurrence of forest-interior species decreased with increasing distance whereas it increased for open-habitat species. Generalists were unaffected by distance. Epixylic, boreal forest-interior cryptogams do occur in matrix habitats such as clear-cuts. In addition, they are associated with the matrix edge because of a favourable microclimate closer to the mature forest on southern matrix edges. Retention and creation of dead wood in clear-cuts along the edges to focal habitats is a feasible way to enhance the long-term persistence of epixylic habitat specialists in fragmented landscapes. The proposed management measures should be performed in the whole stand as it matures, since microclimatic edge effects diminish as the matrix habitat matures. We argue that management that aims to increase habitat quality in matrix habitats bordering focal habitats should increase the probability of long-term persistence of habitat specialists.     

Linking alternative food sources to winter habitat selection of herbivores in overbrowsed landscapes

During winter, ungulates in boreal forests must cope with high energetic costs related to locomotion in deep snow and reduced forage abundance and quality. At high density, ungulates face additional constraints, because heavy browsing reduces availability of woody browse, the main source of forage during winter. Under these severe conditions, large herbivores might forage on alternative food sources likely independent of browsing pressure, such as litterfall or windblown trees. We investigated the influence of alternative food sources on winter habitat selection, by studying female white-tailed deer (Odocoileus virginianus) living in 2 landscapes with contrasted browse abundance, recently logged and regenerated landscapes, in a population at high density and on a large island free of predators. We fitted 21 female white-tailed deer with Global Positioning System (GPS) collars and delineated winter home ranges and core areas. We measured snow conditions in different habitat categories and sampled vegetation in the core areas and in the rest of the home ranges to determine how forage abundance, protective cover, and snow conditions influenced habitat selection within the home range. In both landscapes, deer were less likely to use open habitat categories as snow accumulated on the ground. At a finer scale, deer inhabiting the regenerated landscape intensively used areas where balsam fir cover was intermediate with greater balsam fir browse density than in the rest of the home range. In the recently logged landscape, deer were more likely to be found near edges between clear-cuts and balsam fir stands and in areas where windblown balsam fir trees were present; the latter being the most influential variable. Although balsam fir browse was sparse and mainly out of reach in this landscape, deer increased the use of areas where it was present. Our results offer novel insights into the resource selection processes of northern ungulates, as we showed that access to winter forage, such as woody browse and alternative food sources, depends on climatic conditions and stochastic events, such as abundant compacted snow or windthrows. To compensate for these scarce and unpredictable food supplies, deer selected habitat categories, but mostly areas within those habitat categories, where the likelihood of finding browse, litterfall, and windblown trees was greatest. © 2011 The Wildlife Society.     

Widespread distribution of Pine martens (<Emphasis Type="Italic">Martes martes</Emphasis>) in a fragmented suburban landscape

Pine martens (Martes martes) are forest specialists that depend either on large patches of forest or on the absence of barriers between smaller forest patches. It thus seems likely that they would disappear from landscapes with heavily fragmented forests and a high density of presumptive barriers that are typical of Central Europe. We studied the distribution of pine martens in a suburban landscape characterised by fragmented forests and a high density of presumptive barriers (e.g. housing areas, roads). We assessed the presence of pine martens using camera traps in a sample of 170 1?×?1-km quadrats and used occupancy modelling to account for imperfect detection. We found an almost complete and countrywide distribution of the pine marten. Larger roads and housing areas were not negatively related to its current distribution as we predicted. We conclude that pine martens are capable to survive in some heavily fragmented landscapes.     

Socio-spatial ecology of pine marten (Martes martes) in conifer forests,Ireland

Understanding the social organisation and spacing patterns of wildlife populations is an important aspect of conservation management and applied science. The present study investigated the spatial ecology of pine marten (Martes martes) inhabiting conifer forests in Ireland, the largest habitat resource available for the species. It represented the first study of pine marten spacing patterns in Irish conifer forests. Pine marten (n?=?7; five males and two females) were live-trapped and radio-tracked for between 4 and 10 months from March 2008 to March 2009. Mean annual home-range estimates (95 % fixed kernel) for males (150.7 ha) were generally larger than those of females (90.2 ha). There was considerable inter-seasonal overlap in home ranges (approx 85 %) with less inter-sexual (12.0 %) or intra-sexual (11.8 %) overlap, although the sample size of individuals for comparison was small. Pine marten home ranges were stable from season to season. Core ranges varied in size from 10.6 to 104.1 ha, and as a mean percentage of home-range area were 22.9 and 42.5 % for males and females, respectively. In terms of forest management, potential under occupancy of available space by pine marten and vulnerability of very small core ranges to clear felling practices needs further research to determine any impacts on individuals and populations.     

Designing Timber Harvesting to Enhance New Zealand Falcon Populations

Previous breeding-season studies of threatened New Zealand falcons (Falco novaeseelandiae) in plantation forests have suggested that falcons benefit when harvesting creates a mosaic of differently aged stands, especially where young and mature tree stands are adjacent. Thus, changes in the rate and pattern of harvesting may affect habitat heterogeneity by altering the size and distribution of forest patches. We sought to determine guidelines for harvesting that would most benefit falcons by increasing the carrying capacity of the forest for falcons. We used radio-tracking to determine the home-range sizes of non-breeding falcons over 3 seasons and compared winter home-range overlap in the most-selected land cover types by falcons (mature-young edges and open patches) with other land cover types. The distribution of open patches and edges between mature stands and recently cleared areas affected falcon home ranges, home-range overlap, and the likelihood of nesting. Specifically, home ranges were smaller as the density of edges and percentage of open patch increased, and there was greater home-range overlap between individuals in the most-selected land cover types. Numbers of falcons decreased as the size of open patches increased, concomitant with a decrease in edge size, the number of edge borders, and the number of open patches. The likelihood of nesting also decreased as open patch size increased. Our results indicate that smaller open patches spread through a forest, maximizing the amount of mature-young edges, will favor smaller home ranges and therefore potentially greater numbers of falcons. We recommend harvesting protocols that ensure that open patches (0–3-yr-old stands) are <4 km² in size and retain at least small stands of mature pine to maintain a high density of edges. Similar protocols may increase the carrying capacity for other species occurring in managed systems involving fragmented landscapes or small reserves. © 2021 The Wildlife Society.