Behavioral switching in Magellanic woodpeckers reveals perception of habitat quality at different spatial scales

Context

The switching pattern between behavioral modes provides a mechanistic basis for understanding how animals perceive and memorize the habitat quality in their home ranges.

Objectives

We assessed if Magellanic woodpeckers (Campephilus magellanicus) move based on habitat quality at local (neighboring trees) and home range scales.

Methods

We used state-space models to examine the relationship between remotely-sensed estimates of habitat quality (tree decay) and movement of adult woodpeckers tracked with GPS telemetry in southern Chile.

Results

Woodpeckers spent most time (>?80%) in the area-restricted search (ARS) mode in contrast to the exploratory transient mode, characterized by frequent directional displacements (>?50 m). The extent to which individuals switched between behavioral modes was related to habitat quality at different scales. Woodpeckers switched to and remained in the ARS mode when encountering moderate levels of heterogeneity in habitat quality. At very low or high heterogeneity levels, however, individuals switched to and remained in the transient mode, respectively. Likewise, as habitat quality declined locally and across home range, woodpeckers were more likely to adopt a transient mode.

Conclusions

Although woodpeckers seemed to easily perceive and memorize habitat quality at different spatial scales, our results suggest that spatial memory will less effective under extreme levels of habitat heterogeneity.

     

Responses of Chilean forest birds to anthropogenic habitat fragmentation across spatial scales

Although it is recognized that anthropogenic forest fragmentation affects habitat use by organisms across multiple spatial scales, there is uncertainty about these effects. We used a hierarchical sampling design spanning three spatial scales of habitat variability (landscape > patch > within-patch) and generalized mixed-effect models to assess the scale-dependent responses of bird species to fragmentation in temperate forests of southern Chile. The abundances of nine of 20 bird species were affected by interactions across spatial scales. These interactions resulted in a limited effect of within-patch habitat structure on the abundance of birds in landscapes with low forest cover, suggesting that suitable local habitats, such as sites with dense understory cover or large trees, are underutilized or remain unused in highly fragmented landscapes. Habitat specialists and cavity-nesters, such as tree-trunk foragers and tapaculos, were most likely to exhibit interactions across spatial scales. Because providing additional sites with dense understory vegetation or large habitat trees does not compensate the negative effect of the loss of forest area on bird species, conservation strategies should ensure the retention of native forest patches in the mixed-use landscapes.     

Landscape composition influences roe deer habitat selection at both home range and landscape scales

Understanding how patterns of habitat selection vary in relation to landscape structure is essential to predict ecological responses of species to global change and inform management. We investigated behavioural plasticity in habitat selection of roe deer (Capreolus capreolus) in relation to variable habitat availability across a heterogeneous agricultural landscape at the home range and landscape scales. As expected, woodland was heavily selected, but we found no functional response for this habitat, i.e. no shift in habitat selection with changing habitat availability, possibly due to the presence of hedgerows which were increasingly selected as woodlands were less abundant. Hedgerows may thus function as a substitutable habitat for woodlands by providing roe deer with similar resources. We observed a functional response in the use of hedgerows, implying some degree of landscape complementation between hedgerows and open habitats, which may in part compensate for lower woodland availability. We also expected selection for woodland to be highest at the wider spatial scale, especially when this habitat was limiting. However, our results did not support this hypothesis, but rather indicated a marked influence of habitat composition, as both the availability and distribution of resources conditioned habitat selection. There was no marked between-sex difference in the pattern of habitat selection at either scale or between seasons at the landscape scale, however, within the home range, selection did differ between seasons. We conclude that landscape structure has a marked impact on roe deer habitat selection in agricultural landscapes through processes such as landscape complementation and supplementation.     

Projecting land use transitions at forest fringes in the Philippines at two spatial scales

This paper presents two applications of a spatially explicit model of land use change at two spatial scales: a nation-wide application for the Philippines at relatively coarse resolution and an application with high spatial resolution for one island of the Philippines: Sibuyan island, Romblon province. The model is based on integrated analysis of socio-economic and biophysical factors that determine the allocation of land use change in combination with the simulation of the temporal dynamics (path-dependence and reversibility of changes), spatial policies and land requirements. Different scenarios of near-future developments in land use pattern are simulated illustrating the effects of implementing spatial policies. Results from the coarse scale model with national extent mainly serve to identify the overall pattern of land use change and hot zones of deforestation. The detailed application provides more insight in the pattern of land use change and its consequences for ecological processes. The use of the results for environmental assessments is illustrated by calculating spatial indices to assess the impact of land use change on forest fragmentation. It is concluded that spatially explicit modeling of land use change yields important information for environmental management and land use planning. The applications illustrate that the scale of analysis is an important determinant of the model configuration, the interpretation of the results and the potential use by stakeholders. There is no single, optimal, scale for land use change assessments. Each scale enables different types of analysis and assessment: applications at multiple scales therefore give complementary information needed for environmental management.This revised version was published online in May 2005 with corrections to the Cover Date.     

Extent-dependent habitat selection in a migratory large herbivore: road avoidance across scales

Context

In southwestern Alberta, human development, including roads, is encroaching on the landscape and into the range of a partially migratory population of elk (Cervus elaphus).

Objectives

To quantify factors influencing among- and within-home-range selection of winter range in this population.

Methods

We studied individual habitat selection and road avoidance at two biologically relevant spatial scales. We outlined availability extents for 107 individual elk-years based on observed fall migration distance, and based on a minimum convex polygon around winter telemetry relocations. To model the response by elk to road disturbance, we fit a habitat-selection model to each elk-year at each of the two availability extents, and examined population-level and individual variation in space-use. We then evaluated the relationship between inferred selection at the two scales and the functional response in selection.

Results

Roads had a ubiquitous influence on elk across scales. Elk, individually and as a population, avoided roads when migrating to their winter range and within this seasonal home range. Individual elk that avoided roads more strongly relative to the population did so at both scales of analysis.Further, the avoidance of low-use roads decreased with increasing road density. These results support bottom-up habitat-selection patterns (i.e., scale-independent) and functional response in habitat selection.

Conclusions

Overall, using a multi-scale habitat selection analysis, we show that road avoidance is a major determinant of elk space-use behaviour across multiple scales. Consequently, any new road construction or increases in road-use intensity could have detrimental effects on migratory elk populations by restricting space-use.

     

Effects of spatial habitat heterogeneity on habitat selection and annual fecundity for a migratory forest songbird

Understanding how spatial habitat patterns influence abundance and dynamics of animal populations is a primary goal in landscape ecology. We used an information-theoretic approach to investigate the association between habitat patterns at multiple spatial scales and demographic patterns for black-throated blue warblers (Dendroica caerulescens) at 20 study sites in west-central Vermont, USA from 2002 to 2005. Sites were characterized by: (1) territory-scale shrub density, (2) patch-scale shrub density occurring within 25 ha of territories, and (3) landscape-scale habitat patterns occurring within 5 km radius extents of territories. We considered multiple population parameters including abundance, age ratios, and annual fecundity. Territory-scale shrub density was most important for determining abundance and age ratios, but landscape-scale habitat structure strongly influenced reproductive output. Sites with higher territory-scale shrub density had higher abundance, and were more likely to be occupied by older, more experienced individuals compared to sites with lower shrub density. However, annual fecundity was higher on sites located in contiguously forested landscapes where shrub density was lower than the fragmented sites. Further, effects of habitat pattern at one spatial scale depended on habitat conditions at different scales. For example, abundance increased with increasing territory-scale shrub density, but this effect was much stronger in fragmented landscapes than in contiguously forested landscapes. These results suggest that habitat pattern at different spatial scales affect demographic parameters in different ways, and that effects of habitat patterns at one spatial scale depends on habitat conditions at other scales.     

Quantifying habitat specificity to assess the contribution of a patch to species richness at a landscape scale

Assessing and predicting the species richness of a complex landscape remains a problem because there is no simple scaling function of species richness in a heterogeneous environment. Furthermore, the potential value of an area for biodiversity conservation may depend on which, rather than how many, species the area contains. This paper shows how we can objectively evaluate the contribution of an area, e.g., a habitat patch, to larger-scale plant species richness, e.g., a landscape composed of patches of several habitat types, and how we can test hypotheses that attempt to explain this contribution. We quantified the concept of habitat specificity to assess the proportion of each observed plant population that is concentrated within a given spatial element. A case study of a biodiversity-monitoring program in the Swiss Canton of Aargau showed that the relative contribution of the three main types of land use to the overall species richness differed strongly between higher taxa (vascular plants and molluscs). However, the type of data, i.e., presence-absence or abundance, was not important. Resampling of the plant data suggested that stratification provided an unbiased estimate of relative specificity, whereas unstratified sampling caused bias even for large samples. In a second case study of vascular plants in an agricultural landscape in central Switzerland, we tested whether the type, size or shape of a landscape element can predict its contribution to the species richness of the landscape. Habitat types that were less frequently disturbed contributed more per m² to landscape species richness than more frequently disturbed ones. Contrary to expectation, patch size was negatively correlated to specificity per m² for arable fields, whereas patch shape appeared to be unrelated to the specificity per m² both for arable fields and for meadows. The specificity approach provides a solution to the problem of scaling species richness and is ideally suited for testing hypotheses on the effect of landscape structure on landscape species richness. Specificity scores can easily be combined with measures of other aspects of rarity to assess the contribution of a spatial element to conservation goals formulated at regional, national or global level.     

Site fidelity of female caribou at multiple spatial scales

Studies of site fidelity have been hampered by arbitrary designations of spatial scale and the lack of null models for comparison. We generated null expectations of fidelity at different scales from the distribution of radio-tracked animals in a population. We applied the models to space use of satellite-tracked caribou (Rangifer tarandus caribou), the most vagile nonvolant terrestrial animal, from populations representing sedentary and migratory ecotypes. We compared distances between consecutive-year locations of adult females to expectations based on the total range and seasonal range of each population. At the scale of the total range, sedentary and migratory caribou displayed remarkably similar philopatry, despite a 30-fold difference in size of their population ranges, from time of calving (late May) to breeding (late October). The most intense fidelity occurred during post-calving when, on average, sedentary and migratory females returned to as near as 6.7 km and 123 km, respectively, of locations occupied the previous year. At the scale of the seasonal range, the ecotypes differed. Sedentary caribou still displayed fidelity from calving to breeding; migratory caribou exhibited fidelity only during late autumn. For migratory, but not sedentary caribou, inter-year distances during winter were negatively correlated with age, implying that older females were more philopatric. We conclude that reproductive activities delimit the season of fidelity of female caribou of both ecotypes, and that scale-dependent ecotypic differences in fidelity may reflect different factors of population limitation. A spatially-explicit approach to site fidelity is essential for synthesizing patterns across studies.     

Using airborne LiDAR to assess spatial heterogeneity in forest structure on Mount Kilimanjaro

Context

Field inventory plots which usually have small sizes of around 0.25–1 ha can only represent a sample of the much larger surrounding forest landscape. Based on airborne laser scanning (LiDAR) it has been shown for tropical forests that the bias in the selection of small field plots may hamper the extrapolation of structural forest attributes to larger spatial scales.

Objectives

We conducted a LiDAR study on tropical montane forest and evaluated the representativeness of chosen inventory plots with respect to key structural attributes.

Methods

We used six forest inventory and their surrounding landscape plots on Mount Kilimanjaro in Tanzania and analyzed the similarities for mean top-of-canopy height (TCH), aboveground biomass (AGB), gap fraction, and leaf-area index (LAI). We also analyzed the similarity in gap-size frequencies for the landscape plots.

Results

Mean biases between inventory and landscape plots were large reaching as much as 77% for gap fraction, 22% for LAI or 15% for AGB. Despite spatial heterogeneity of the landscape, gap-size frequency distributions were remarkably similar between the landscape plots.

Conclusions

The study indicates that biases in field studies of forest structure may be strong. Even when mean values were similar between inventory and landscape plots, the mostly non-normally distributed probability densities of the forest variable indicated a considerable sampling error of the small field plot to approximate the forest variable in the surrounding landscape. This poses difficulties for the spatial extrapolation of forest structural attributes and for assessing biomass or carbon fluxes at larger regional scales.

     

Quantifying patch distribution at multiple spatial scales: Applications to wildlife-habitat models

Multiscale analyses are widely employed for wildlife-habitat studies. In most cases, however, each scale is considered discrete and little emphasis is placed on incorporating or measuring the responses of wildlife to resources across multiple scales. We modeled the responses of three Arctic wildlife species to vegetative resources distributed at two spatial scales: patches and collections of patches aggregated across a regional area. We defined a patch as a single or homogeneous collection of pixels representing 1 of 10 unique vegetation types. We employed a spatial pattern technique, three-term local quadrat variance, to quantify the distribution of patches at a larger regional scale. We used the distance at which the variance for each of 10 vegetation types peaked to define a moving window for calculating the density of patches. When measures of vegetation patch and density were applied to resource selection functions, the most parsimonious models for wolves and grizzly bears included covariates recorded at both scales. Seasonal resource selection by caribou was best described using a model consisting of only regional scale covariates. Our results suggest that for some species and environments simple patch-scale models may not capture the full range of spatial variation in resources to which wildlife may respond. For mobile animals that range across heterogeneous areas we recommend selection models that integrate resources occurring at a number of spatial scales. Patch density is a simple technique for representing such higher-order spatial patterns.     

Quantifying patch distribution at multiple spatial scales: Applications to wildlife-habitat models

Multiscale analyses are widely employed for wildlife-habitat studies. In most cases, however, each scale is considered discrete and little emphasis is placed on incorporating or measuring the responses of wildlife to resources across multiple scales. We modeled the responses of three Arctic wildlife species to vegetative resources distributed at two spatial scales: patches and collections of patches aggregated across a regional area. We defined a patch as a single or homogeneous collection of pixels representing 1 of 10 unique vegetation types. We employed a spatial pattern technique, three-term local quadrat variance, to quantify the distribution of patches at a larger regional scale. We used the distance at which the variance for each of 10 vegetation types peaked to define a moving window for calculating the density of patches. When measures of vegetation patch and density were applied to resource selection functions, the most parsimonious models for wolves and grizzly bears included covariates recorded at both scales. Seasonal resource selection by caribou was best described using a model consisting of only regional scale covariates. Our results suggest that for some species and environments simple patch-scale models may not capture the full range of spatial variation in resources to which wildlife may respond. For mobile animals that range across heterogeneous areas we recommend selection models that integrate resources occurring at a number of spatial scales. Patch density is a simple technique for representing such higher-order spatial patterns.     

Effects of agroecosystem landscape complexity on small mammals: a multi-species approach at different spatial scales

Landscape Ecology - The effect of landscape complexity on biodiversity is an important topic in landscape ecology, and spatial scale is key to understand true species-landscape relationships. We...     

Using a species-centered approach to predict bird community responses to habitat fragmentation

Landscape Ecology - The relative importance of habitat fragmentation versus loss on species richness has been much debated. However, recent findings that fragmentation effects are relatively weak...     

Butterflies in Swedish grasslands benefit from forest and respond to landscape composition at different spatial scales

Context

Loss and fragmentation of semi-natural grasslands has critically affected many butterfly species in Europe. Habitat area and isolation can have strong effects on the local biodiversity but species may also be strongly affected by the surrounding matrix.

Objectives

We explored how different land cover types in the landscape explained the occurrence of butterfly species in semi-natural grasslands.

Methods

Using data from 476 semi-natural grasslands in Sweden, we analysed the effect of matrix composition on species richness and occurrence. Additionally, we analysed at which spatial scales butterflies responded to matrix types (forests, semi-natural grasslands, arable land and water).

Results

Forest cover showed the strongest positive effect on species richness, followed by semi-natural grasslands. Forest also had a positive effect on red-listed species at local scales. Responses to matrix composition were highly species-specific. The majority of the 30 most common species showed strong positive responses to the amount of forest cover within 200–500 m. There was a smaller group of species showing a positive response to arable land cover within 500–2000 m. Thirteen species showed positive responses to the amount of semi-natural grasslands, generally at larger scales (10–30 km).

Conclusions

Our study showed that surrounding forest is beneficial for many grassland butterfly species and that forests might mitigate the negative effects of habitat loss caused by agricultural intensification. Also, semi-natural grasslands were an important factor for species richness at larger spatial scales, indicating that a landscape consisting mainly of supporting habitats (i.e. forests) are insufficient to sustain a rich butterfly fauna.

     

The structure of boreal old-growth forests changes at multiple spatial scales over decades

Landscape Ecology - Changes in the structure of boreal old-growth forests are typically studied at a specific spatial scale. Consequently, little is known about forest development across different...     

How to define a patch: a spatial model for hierarchically delineating organism-specific habitat patches

Landscape analysis and delineation of habitat patches should take into account organism-specific behavioral and perceptual responses to landscape structure because different organisms perceive and respond to landscape features over different ranges of spatial scales. The commonly used methods for delineating habitat based on rules of contiguity do not account for organism-specific responses to landscape patch structure and have undesirable properties, such as being dependent on the scale of base map used for analysis. This paper presents an improved patch delineation algorithm, “PatchMorph,” which can delineate patches across a range of spatial scales based on three organism-specific thresholds: (1) land cover density threshold, (2) habitat gap maximum thickness (gap threshold), and (3) habitat patch minimum thickness (spur threshold). This algorithm was tested on an “idealized” landscape with landscape gaps and spurs of known size, and delineated patches as expected. It was then applied to delineate patches from a neutral random fractal landscape, which showed that as the input gap and spur thickness thresholds were increased, the number of patches decreased from 59 (low thresholds) patches to 1 (high thresholds). The algorithm was then applied to model western yellow-billed cuckoo (Coccyzus americanus occidentalis) nesting habitat patches based on spur and gap thresholds specific to this organism. Both these analyses showed that fewer patches were delineated by PatchMorph than by rules of contiguity, and those patches were larger, had smoother edges, and had fewer gaps within the patches. This algorithm has many applications beyond those presented in this paper, including habitat suitability analysis, spatially explicit population modeling, and habitat connectivity analysis.     

Stop using dichotomous terms to reference observations of scale-dependent habitat selection

Context

Many studies dichotomize habitat selection into “local” or “landscape” effects, with little explanation regarding what each represents. Ambiguous use of these terms across studies may confound observations of selection operating across different spatiotemporal resolutions and impede synthesis of scale-dependent habitat selection.

Objective

To examine the consistency of use of the terms “local” and “landscape” level habitat selection and evaluate potential implications for conservation science.

Methods

We reviewed 136 multi-level studies observing local and/or landscape effects. From each study, we identified which of Johnson’s (Ecology 61:65–71, 1980) selection orders was observed at the local and landscape scale. We assessed consistency in the selection order observed at each scale.

Results

At the local scale, 54% of studies observed 3rd order selection and 38% of studies observed 4th order selection. At the landscape scale, 64% of studies observed 2nd order selection, while only 8% of studies observed 1st order selection. Overlap also occurred; 2nd order selection was observed at the local scale in 8% of studies, while 3rd and 4th order selection was observed at the landscape scale in 24 and 3% of studies, respectively.

Conclusions

Selection orders observed at local and landscape scales are inconsistent across studies, making comparisons and synthesis difficult. This inconsistency makes the terms “local” and “landscape” meaningless, and may lead to misidentification of limiting factor(s) most important for conservation efforts. Dichotomous terms should no longer be used in reference to levels of selection, but in reference to specific explanatory variables whose characteristic scale(s) best fit the appropriate definition.

     

Assessing the influence of resource covariates at multiple spatial scales: an application to forest-dwelling caribou faced with intensive human activity

Efforts in isolating the relative effects of resources and disturbances on animal-distribution patterns remain hindered by the difficulty of accounting for multiple scales of resource selection by animals with seasonally dynamic drivers. We developed multi-scale, seasonal models to explore how local resource selection by the threatened forest-dwelling woodland caribou (Rangifer tarandus caribou) was influenced by both broad-scale landscape context and local resource heterogeneity in the intensively managed region of Charlevoix, Québec, Canada, located on the southern border of the North American caribou range. We estimated resource selection functions using 23 GPS-collared caribou monitored from 2004 to 2006 and landscape data on vegetation classes, terrain conditions, and roads. We found evidence of thresholds in road “proximity” effects (up to 1.25 km), which underscores the importance of including landscape context variables in addition to locally measured variables, and of fitting seasonal-specific models given temporal variation in the magnitude of selection and optimal scale of measurement. Open lichen woodlands were an important cover type for caribou during winter and spring, whereas deciduous forests, wetlands, and even young disturbed stands became important during calving and summer. Caribou consistently avoided roads and rugged terrain conditions at both local and landscape levels. Landscape context fundamentally constrains the choices available to animals, and we showed that failing to consider landscape context, or arbitrarily choosing an inappropriate scale for measuring covariates, may provide biased inferences with respect to habitat selection patterns. Effective habitat management for rare or declining species should carefully consider the hierarchical nature of habitat selection.     

Integrating landscape resistance and multi-scale predictor of habitat selection for amphibian distribution modelling at large scale

Context

Species distribution modelling is a common tool in conservation biology but two main criticisms remain: (1) the use of simplistic variables that do not account for species movements and/or connectivity and (2) poor consideration of multi-scale processes driving species distributions.

Objectives

We aimed to determine if including multi-scale and fine-scale movement processes in SDM predictors would improve accuracy of SDM for low-mobility amphibian species compared with species-level analysis.

Methods

We tested and compared different SDMs for nine amphibian species with four different sets of predictors: (1) simple distance-based predictors; (2) single-scale compositional predictors; (3) multi-scale compositional predictors with a priori selection of scale based on knowledge of species mobility and scale-of-effect; and (4) multi-scale compositional predictors calculated using a friction-based functional grain to account for resource accessibility with landscape resistance to movement.

Results

Using friction-based functional grain predictors produced slight to moderate improvements of SDM performance at large scale. The multi-scale approach, with a priori scale selection, led to ambiguous results depending on the species studied, in particular for generalist species.

Conclusion

We underline the potential of using a friction-based functional grain to improve SDM predictions for species-level analysis.

     

Saproxylic species are linked to the amount and isolation of dead wood across spatial scales in a beech forest

Context

Dead wood is a key habitat for saproxylic species, which are often used as indicators of habitat quality in forests. Understanding how the amount and spatial distribution of dead wood in the landscape affects saproxylic communities is therefore important for maintaining high forest biodiversity.

Objectives

We investigated effects of the amount and isolation of dead wood on the alpha and beta diversity of four saproxylic species groups, with a focus on how the spatial scale influences results.

Methods

We inventoried saproxylic beetles, wood-inhabiting fungi, and epixylic bryophytes and lichens on 62 plots in the Sihlwald forest reserve in Switzerland. We used GLMs to relate plot-level species richness to dead wood amount and isolation on spatial scales of 20–200 m radius. Further, we used GDMs to determine how dead wood amount and isolation affected beta diversity.

Results

A larger amount of dead wood increased beetle richness on all spatial scales, while isolation had no effect. For fungi, bryophytes and lichens this was only true on small spatial scales. On larger scales of our study, dead wood amount had no effect, while greater isolation decreased species richness. Further, we found no strong consistent patterns explaining beta diversity.

Conclusions

Our multi-taxon study shows that habitat amount and isolation can strongly differ in the spatial scale on which they influence local species richness. To generally support the species richness of different saproxylic groups, dead wood must primarily be available in large amounts but should also be evenly distributed because negative effects of isolation already showed at scales under 100 m.