Home Range Scale Research Articles

Habitat preferences for Long-eared Owls Asio otus and Little Owls Athene noctua in semi-arid environments at three spatial scales

Capsule There is a relationship between owl numbers and the availability of the agri-forest patchwork. Aims To model habitat preferences at three different scales of two predators largely neglected within the framework of Environmental Impact Assessment (EIA) studies. Methods We studied habitat preferences of Long-eared Owls and Little Owls by comparing habitat composition around 28 and 78 occupied territories respectively with 55 non-occupied territories in Alicante (eastern Spain). Generalized linear models were used to examine patterns of habitat preference at three different spatial scales: nest-site, home range and landscape. Results At the nest-site scale, Long-eared Owls preferred wooded areas with few paved roads while Little Owls preferred arid plantations. Furthermore, the probability of finding an occupied territory increased with the proximity of another occupied territory in the surroundings. The home range scale models mirror the feeding requirements of the owls. Thus, Long-eared Owls occupied areas with high percentages of forest, arid plantations, edges between these two land uses, short distances between nests, with presence of conspecifics and little human disturbance. Little Owls occupied arid plantations with high availability of linear structures and the proximity of villages. At the landscape scale, Long-eared Owls eluded extensive forests, and Little Owls preferred arid plantations. Conclusions We suggest a hierarchical process of habitat selection for both owls regarding fitting trophic resources at the broadest scales and adequate sites for breeding and roosting at the smallest scale. EIA studies must consider that protecting small areas around single nests may not be an efficient conservation option compared with preserving clusters of territories for both species.

Habitat selection of adult mooseAlces alcesat two spatial scales in central Finland

The habitat selection criteria of mooseAlces alcesat several scales are the basic sets of information needed in moose management planning. We studied moose habitat use in central Finland during 1993–1996 using data from radio collared moose, satellite image based forest and land cover data, and applied the principles of compositional analysis. The habitat compositions of 54 home ranges (10 males during summer, six males during winter, 23 females during summer and 15 females during winter) were first compared with the overall landscape. The habitat compositions around moose locations within their home ranges were then compared with the habitat composition of the home range. Seasons and sexes were compared at both scales. In summer, there was only a slight difference between moose home ranges and the overall landscape. Based on tree species composition, home ranges are located in slightly more fertile areas than the overall landscape. Within their home ranges, moose favoured non‐pine dominated habitats and mature forests, and avoided human settlements. In winter, the moose home ranges included significantly more pine‐dominated plantations and other young successional stages than the overall landscape. The role of pine‐dominated peatland forests/ shrub land was especially pronounced in winter. Winter home ranges included less agricultural land and human settlements than the overall landscape, probably due to the more distant location of important winter habitats from man‐made landscapes. Within the home ranges, both sexes used non‐pine dominated habitats more, and mature forests and human settlements less than expected. At the home range scale, there were no statistical differences between the sexes with respect to habitat use in either season. Within their home ranges, males and females used slightly different habitats during both seasons, suggesting spatially segregated habitat use by the individual sexes. The difference is more clear in winter when males tend to use more pine‐dominated, young successional habitats than females. Compared to the situation in the summer, winter ranges are located in slightly more pine‐dominated habitats with fewer settlements and agricultural fields. The shift in habitat use between the two seasons is more pronounced with respect to habitat use within the home range. Our results indicate that moose habitat selection criteria vary among different hierarchical levels of selection. We stress the importance of multi‐scale assessment of the habitat and other resource selection of animals.

Sex-Specific Movements and Habitat Use by Elk in the Cascade Range of Washington

I studied sex-specific movements and habitat use of Rocky Mountain elk (Cervus elaphus nelsoni) in the Cascade Range of south-central Washington, USA, during 1992-1999. I used 3,059 relocations of 78 radiomarked elk (25 adult males, 26 subadult males, and 27 adult females). Adult males (≥5 yr) consistently migrated from summer-autumn home ranges earlier than other elk, contrary to expectations, but the timing of spring migration was similar among sex-age classes. Using compositional analysis, I found habitat use of adult and subadult (≤4 yr) male elk during winter and summer-autumn were similar at home-range and patch scales. However, use compositions for cover types and topographic features often differed between males and females. Males selected mature semi-closed forest at both scales during summer-autumn. Females demonstrated similar preferences to males at the home-range scale. I did not detect selective use of cover types at the patch scale by females during summer-autumn. I also did not detect selective use of cover types at the home-range scale by males during winter, but males selected conifer forest at the patch scale. In contrast, females selected oak (Quercus spp.) woodland and openings at the home-range scale and used cover types proportional to their availability at the patch scale during winter. All elk located their winter home ranges in relatively steep terrain, but within winter home ranges, males selected gentler slopes than females did. The effects of roads on habitat use differed among sex-age classes of elk; adult males selected summer-autumn home ranges with lower road densities and used patches much farther from roads than did subadult males (x difference = 693.8 m) and females (x difference = 827.4 m). During winter, female elk home ranges had lower road densities, and females used areas farther from roads than adult and subadult males, but differences in effect sizes were small. Data were consistent with the hypothesis that males used environments with predictably less human activity than did female elk.

Winter habitat and travel route selection by wolves in the northern Apennines, Italy

To assess the wolf‐habitat relationship on the home range scale (i.e., third order selection), we developed a resource selection probability function (RSPF) through a multiple logistic regression model based on the winter travel routes of a wolf pack in the northern Apennines, Italy (1991–95). Both travel routes (240 km) and habitat variables were mapped at 1:10 000 scale, digitised as Geographical Information System (GIS) layers, and overlaid with a 100×100 m pixel grid to census all used and unused resource units. Out of 15 covariates, the full model included 10 variables and 4 interaction terms. According to the model, travel routes by wolves were not randomly located within the home range but were clearly associated with selected bio‐physical factors, including human‐related habitat modifications (i.e., roads), which appeared to affect the wolves' resource selection and, ultimately, habitat quality. Using a jackknife procedure, the model correctly classified 73.1% of used resource units and 63.2% of unused resource units. A Monte Carlo test showed a non‐significant effect on the model coefficients of 4 increasing sub‐sampling levels of used resource units, suggesting that autocorrelation of snow‐tracking data exerted little influence on the point estimates of the coefficients. However, given the increased standard error at higher sub‐sampling levels, autocorrelation might have caused an underestimation of the theoretical variance. Although wolves are generally considered habitat generalists, this study shows that patterns of habitat selection are disclosed at finer scales of analysis. In this perspective, resource selection probability functions at finer scales offer different and complementary insight with respect to regional landscape applications, and provide a useful management tool for assessment of habitat quality at the local scale.

Predictive models of habitat preferences for the Eurasian eagle owl Bubo bubo: a multiscale approach

Habitat preference of eagle owls Bubo bubo were examined through comparing habitat composition around 51 occupied cliffs and 36 non‐occupied cliffs in Alicante (E Spain). We employed Generalized Linear Models to examine patterns of habitat preference at three different spatial scales: nest site (7 km2), home range (25 km2), and landscape (100 km2). At the nest site scale, occupied cliffs were more rugged, had a greater proportion of forest surface in the surroundings, and were further from the nearest paved road than unoccupied cliffs. Additionally, probability of having an occupied cliff increased when there was another occupied territory in the surroundings. At both the home range scale and the landscape scale, high probabilities of presence of eagle owls were related to high percentages of Mediterranean scrubland around the cliffs, which are the preferred habitat of European rabbits Oryctolagus cuniculus, the main prey of the owls. We suggest a hierarchical process of habitat selection in the eagle owl concerning suitable trophic resources at the broadest scales and adequate sites for breeding and roosting at the smallest scale. However, it should be noted that some structural features such as the proximity of roads were not necessarily avoided by the owls, but their presence were possibly constrained by systematic killing of individuals. Our paper provides new evidence for the requirement of multi‐scale approaches to gain insight into both the different limiting factors for the persistence of populations and the role of individual perception of the environment in the evolution of habitat selection.

Nest-Site Habitat Use by White-Headed Woodpeckers in the Eastern Cascade Mountains, Washington

The white-headed woodpecker (Picoides albolarvatus) is strongly associated with old-growth ponderosa pine (Pinus ponderosa) forest, a degraded and increasingly uncommon habitat in the Pacific Northwest. We investigated the nest-site habitat use of this species by col- lecting vegetation data at 21 known nest sites in the eastern Cascades of Washington, 12 of which we found in 1999. Sixteen of 17 (94%) nests in the ponderosa pine vegetation zone were in the 72% of the zone that occurred below 1219 m, and 15 (88%) nests were on slopes of <20% (which comprised 48% of the zone); the total area characterized by both slopes <20% and elevation below 1219 m was 181,664 ha or 33.6% of the vegetation zone. Most (16 of 21) nests were in ponderosa pines and 81% (17 of 21) were in snags. The nest snags and trees were generally large, with a mean diameter at breast height of 51.5 cm (sx = 5.13). The mean height of nest snags and trees was 12.6 m (sx = 2.33), and the mean height of the nest cavity entrance was 5.8 m (sx = 1.37). Compared to random sites located <1 km from each nest, nest sites were characterized by a greater abundance, size, and basal area of large trees and snags, primarily ponderosa pines. Management of habitat for this species should include retention of 6 to 8 large snags/0.8 ha and 8 to 10 large trees/0.8 ha in the immediate vicinity of nesting areas. Habitat requirements at the home range scale should be investigated.

Assessing the suitability of central European landscapes for the reintroduction of Eurasian lynx

Summary After an absence of almost 100 years, the Eurasian lynx Lynx lynx is slowly recovering in Germany along the German–Czech border. Additionally, many reintroduction schemes have been discussed, albeit controversially, for various locations. We present a habitat suitability model for lynx in Germany as a basis for further management and conservation efforts aimed at recolonization and population development. We developed a statistical habitat model using logistic regression to quantify the factors that describe lynx home ranges in a fragmented landscape. As no data were available for lynx distribution in Germany, we used data from the Swiss Jura Mountains for model development and validated the habitat model with telemetry data from the Czech Republic and Slovenia. We derived several variables describing land use and fragmentation, also introducing variables that described the connectivity of forested and non‐forested semi‐natural areas on a larger scale than the map resolution. We obtained a model with only one significant variable that described the connectivity of forested and non‐forested semi‐natural areas on a scale of about 80 km2. This result is biologically meaningful, reflecting the absence of intensive human land use on the scale of an average female lynx home range. Model testing at a cut‐off level of P &gt; 0·5 correctly classified more than 80% of the Czech and Slovenian telemetry location data of resident lynx. Application of the model to Germany showed that the most suitable habitats for lynx were large‐forested low mountain ranges and the large forests in east Germany. Our approach illustrates how information on habitat fragmentation on a large scale can be linked with local data to the potential benefit of lynx conservation in central Europe. Spatially explicit models like ours can form the basis for further assessing the population viability of species of conservation concern in suitable patches.

Seasonal Habitat Selection by Raccoons (Procyon lotor) in Intensively Managed Pine Forests of Central Mississippi

Raccoons (Procyon lotor) are ecological generalists, existing in diverse landscapes. Although general habitat use patterns of raccoons have been extensively described, little research has examined raccoon habitat selection within landscapes managed intensively for wood fiber production. Furthermore, no published studies using radio-telemetry have detailed raccoon habitat selection at multiple spatial scales. We monitored 31 raccoons on a 2000 ha area characterized by short-rotation (<35 y) pine forests in central Mississippi during 1996–1997 and examined seasonal habitat selection at three spatial scales. Habitat selection at the home range scale differed (P = 0.004) between genders. Gender and season interacted to affect habitat selection at the core area scale of selection. Both male and female core areas contained greater proportions of mature hardwood habitats during breeding and young-rearing. Habitat use within home ranges, as determined by point locations, did not differ (P > 0.440) with gender or season. However, raccoons used habitats disproportionately (P = 0.016) relative to habitat composition of the home range. Our findings illustrate the importance of examining individual habitat selection at multiple scales, as raccoon habitat selection in our study varied by scale. Furthermore, our results indicate the importance of hardwood dominated habitats for raccoons existing in pine-dominated landscapes.

Bed-Site Selection by Desert Mule Deer in Southern Arizona

Bed-Site Selection by Desert Mule Deer in Southern Arizona

How to test habitat selection at the home range scale: A resampling random windows technique

Habitat selection studies at the home range scale involve testing whether an animal selects a particular spatial arrangement of habitats within a landscape. We propose a technique based on comparing the landscape pattern indices (LPIs) of observed home ranges with those of a large sample of random windows. In order to determine the appropriate size of the windows, we examined how this variable influences LPIs in a 138-km2 boreal forest block where clearcuts were prevalent. Square random windows of three different sizes (289, 729, and 1156 ha) yielded similar habitat composition proportions but very different values for many of the other LPIs. When compared with values computed for the entire landscape as a single window, most LPIs except composition were very different in the random windows. An example of a comparison between marten (Martes americana Turton) home ranges (n = 11) and square random windows (n = 100) in our study area is given, showing a strong selection for mosaics containing more forest (> 30 years), fewer open regenerating stands, and a larger amount of core area in forest. We conclude that computing LPI values for the entire landscape as a single window is inappropriate for testing habitat selection at the home range scale, and that windows of similar size as the home ranges should be used instead.

Detection and species identification of baleen whale calls

Baleen whales live over extensive home range and time scales. Study of how these animals use their vocalizations for communication requires massive data sampling over long periods. This paper describes a system for automating the sampling and analysis of baleen whale calls. Many species produce stable, homogeneous call structures which lend themselves to automated species identification. We have benchmarked a series of bioacoustical call identification algorithms against a set of blue and fin whale calls while systematically manipulating the signal-to-noise ratio. Blue (Balaenoptera musculus) and fin (B. physalus) whale calls are very stereotypical. Blue whale ‘‘A’’ and ‘‘B’’ calls have fundamental frequencies of approximately 17 Hz, narrow bandwidth, well-defined harmonic structure, and typical duration of 15–25 s. Fin whale ‘‘pulses’’ have fundamental frequencies of approximately 17 Hz, but are broadband in nature and short (approximately 1-s) duration. The results demonstrated a typical tradeoff of speed versus accuracy. The best algorithm was inserted into an underwater sound recording system and its signal-detection theoretic performance was quantified. Results will be discussed with respect to technological, ecological, and conservation aspects of baleen whale bioacoustics. [Project CS-1082 of the Strategic Environmental Research and Development Program.]

Modelling habitat suitability for black-tailed deer ( Odocoileus hemionus columbianus) in heterogeneous landscapes

The California Wildlife Habitat Relationships (CWHR) System is a set of standardized procedures including an information system describing the management status, distribution, life history, and habitat requirements of 643 species of terrestrial vertebrates regularly occurring in California. The original CWHR Database consisted of a series of non-spatial, matrix models, including one for black-tailed deer. A series of second-generation models incorporates explicit spatial relations for use within a geographic information system. These models were designed for landscapes larger than 60 000 ha with a minimum mapping unit of 0.8 ha. As part of our development of a third-generation model applicable to landscape depictions with a minimum mapping unit of 0.06 ha, we assessed the utility of a measure of landscape composition, and an interspersion index, both based on feeding and cover habitat suitability classes found within deer home ranges. General linear model analysis indicated that the percentage of the home rang comprised by each class and the interspersion index were correlated ( P < 0.05) with feeding-cover class, site, the interaction between feeding-cover class and site, and the interaction between home range type (actual or random) and site. The percentage of home ranges comprised by feeding-cover class and the level of interspersion within home ranges differed significantly by suitability class. We detected differences between actual deer home ranges and random home ranges of similar size only within the site that had significant separation in the composition of classes and the interspersion of classes. This suggests that landscape representations resulting in classes with similar composition levels and similar levels of interspersion at the scale of the animal's home range may hinder the assessment of habitat use within home ranges by promoting Type II errors. We demonstrated that organism-centered specifications for extent and grain can be defined from a generic structural representation of the landscape using functional-based models. Spatial extent was defined using the adaptive kernel home range estimator. Within this extent, habitat suitability classed based on feeding and cover produced the grain size for black-tailed deer (mean 0.44 ha, range 0.06–7.79 ha). Furthermore, this approach portrayed the low feeding-high cover matrix class exerting the dominant influence within home ranges. Thus, we suggest measures of landscape composition and interspersion may be useful for characterizing landscapes when assessing habitat use by deer. They may also be of value to natural resource managers attempting to predict the response of deer to proposed changes in land use.

Use of space and habitats by meadow voles at the home range, patch and landscape scales.

Using capture/recapture methods, we examined the spatial usage patterns of Microtus pennsylvanicus within and between experimentally created habitat patches of three sizes (1.0, 0.25 and 0.0625 ha) and between a 20-ha fragmented and a 20-ha continuous habitat landscape. We tested the prediction that home ranges near patch edges would be qualitatively different from those in patch interiors, and that the edge:interior habitat ratio could be used to make predictions concerning the dispersion and spatial use of individuals occupying different sized patches and between landscapes with different habitat structure. We found adult females on patch edges to have larger and more exclusive home ranges, larger body sizes, longer residence times, and to reproduce at a higher frequency than those in patch interiors. These "edge effects" also appeared to be largely responsible for the greater proportion of larger, reproductive females we found in small than larger patches and in the fragmented than in the continuous habitat (control) landscape. The selection of higher quality edge habitats by dominant females and the relegation of sub-dominants to patch interiors provides an explanation for the observed differences in the distribution and performance of females over patches and between landscapes.