Estimating red fox density using non-invasive genetic sampling and spatial capture–recapture modelling

AbstractSpatial capture–recapture modelling (SCR) is a powerful tool for estimating density, population size, and space use of elusive animals. Here, we applied SCR modelling to non-invasive genetic sampling (NGS) data to estimate red fox (Vulpes vulpes) densities in two areas of boreal forest in central (2016–2018) and southern Norway (2017–2018). Estimated densities were overall lower in the central study area (mean = 0.04 foxes per km2 in 2016, 0.10 in 2017, and 0.06 in 2018) compared to the southern study area (0.16 in 2017 and 0.09 in 2018). We found a positive effect of forest cover on density in the central, but not the southern study area. The absence of an effect in the southern area may reflect a paucity of evidence caused by low variation in forest cover. Estimated mean home-range size in the central study area was 45 km2 [95%CI 34–60] for females and 88 km2 [69–113] for males. Mean home-range sizes were smaller in the southern study area (26 km2 [16–42] for females and 56 km2 [35–91] for males). In both study areas, detection probability was session-dependent and affected by sampling effort. This study highlights how SCR modelling in combination with NGS can be used to efficiently monitor red fox populations, and simultaneously incorporate ecological factors and estimate their effects on population density and space use.

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Estimating Red Fox Density Using Non-Invasive Genetic Sampling and Spatial Capture-Recapture Modeling

10.21203/rs.3.rs-325103/v1 ◽

2021 ◽

Author(s):

Lars Lindsø ◽

Pierre Dupont ◽

Lars Rød-Eriksen ◽

Ida Pernille Øystese Andersskog ◽

Kristine Roaldsnes Ulvund ◽

...

Keyword(s):

Home Range ◽

Forest Cover ◽

Red Fox ◽

Ecological Factors ◽

Space Use ◽

Home Range Size ◽

Sampling Effort ◽

Non Invasive ◽

Genetic Sampling ◽

Capture Recapture

Abstract Spatial capture-recapture modelling (SCR) is a powerful tool for estimating densities, population size and space use of elusive animals. Here, we applied SCR modeling to non-invasive genetic sampling (NGS) data to estimate red fox (Vulpes vulpes) densities in two areas of boreal forest in central (2016 - 2018) and southern Norway (2017 - 2018). Estimated densities were overall lower in the northern study area (mean = 0.04 foxes per km2 [95%CI: 0.02-0.09] in 2016, 0.09 [0.05-0.18] in 2017 and 0.07 [0.04-0.13] in 2018) compared to the southern study area (0.16 [0.09-0.26] in 2017 and 0.10 [0.07-0.16] in 2018). We found a positive effect of forest cover on density in the northern, but not the southern study area. The absence of an effect in the southern area may reflect a paucity of evidence caused by low variation in forest cover, but could also be due to climatic differences (e.g., winter severity) between the two areas. Estimated mean home range size in the northern study area was 45 km2 [34-60] for females and 88 km2 [69-113] for males. Mean home range sizes were smaller in the southern study area (26 km2 [16-42] for females and 56 km2 [35-91] for males). In both study areas, detection probability was session-dependent and affected by sampling effort. This study highlights how SCR modeling in combination with NGS can be used to efficiently monitor red fox populations, and simultaneously incorporate ecological factors and estimate their effects on population density and space-use.

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Range-wide factors shaping space use and movements by the Neotropic’s flagship predator: the jaguar

10.32942/osf.io/k2hqz ◽

2020 ◽

Author(s):

Jeffrey James Thompson ◽

Ronaldo Morato ◽

Bernardo Niebuhr ◽

Vanesa Bejarano Alegre ◽

Júlia Emi F. Oshima ◽

...

Keyword(s):

Home Range ◽

Forest Cover ◽

Movement Ecology ◽

Space Use ◽

Home Range Size ◽

Range Size ◽

Anthropogenic Factors ◽

Road Density ◽

Modeling Framework ◽

Transboundary Cooperation

The range-wide management of the jaguar (Panthera onca) depends upon maintaining core populations connected through multi-national, transboundary cooperation, which is dependent upon understanding the movement ecology and space use of jaguars throughout their range. Using 117 telemetry trajectories from 12 ecoregions, we examined the landscape-level environmental and anthropogenic factors related to jaguar home range size and movement parameters. Range-wide and at the ecoregional scale home range size decreased with increasing net productivity and increased with increasing road density. Also, range-wide, home range size decreased with increasing forest cover and decreasing human population density. Movement within home ranges was best explained by a different set of environmental covariates. Range-wide predictions of home range size were consistent with expectations based upon density estimates. Our findings provide a mechanism to evaluate range-wide habitat quality for jaguars and an inferential modeling framework that can be adapted to the conservation of other large terrestrial carnivores.

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Sexual, allometric and forest cover effects on giant anteaters’ movement ecology

PLoS ONE ◽

10.1371/journal.pone.0253345 ◽

2021 ◽

Vol 16 (8) ◽

pp. e0253345

Author(s):

Aline Giroux ◽

Zaida Ortega ◽

Luiz Gustavo Rodrigues Oliveira-Santos ◽

Nina Attias ◽

Alessandra Bertassoni ◽

...

Keyword(s):

Home Range ◽

Body Mass ◽

Forest Cover ◽

Movement Patterns ◽

Space Use ◽

Home Range Size ◽

Range Size ◽

Extreme Weather Events ◽

Environmental Drivers

Knowing the influence of intrinsic and environmental traits on animals’ movement is a central interest of ecology and can aid to enhance management decisions. The giant anteater (Myrmecophaga tridactyla) is a vulnerable mammal that presents low capacity for physiological thermoregulation and uses forests as thermal shelters. Here, we aim to provide reliable estimates of giant anteaters’ movement patterns and home range size, as well as untangle the role of intrinsic and environmental drivers on their movement. We GPS-tracked 19 giant anteaters in Brazilian savannah. We used a continuous-time movement model to estimate their movement patterns (described by home range crossing time, daily distance moved and directionality), and provide an autocorrelated kernel density estimate of home range size. Then, we used mixed structural equations to integratively model the effects of sex, body mass and proportion of forest cover on movement patterns and home range size, considering the complex net of interactions between these variables. Male giant anteaters presented more intensive space use and larger home range than females with similar body mass, as it is expected in polygynous social mating systems. Males and females increased home range size with increasing body mass, but the allometric scaling of intensity of space use was negative for males and positive for females, indicating different strategies in search for resources. With decreasing proportion of forest cover inside their home ranges, and, consequently, decreasing thermal quality of their habitat, giant anteaters increased home range size, possibly to maximize the chances of accessing thermal shelters. As frequency and intensity of extreme weather events and deforestation are increasing, effective management efforts need to consider the role of forests as an important thermal resource driving spatial requirements of this species. We highlight that both intrinsic and environmental drivers of animal movement should be integrated to better guide management strategies.

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Home range size, space use and resource selection of griffon vultures in an insular environment

Journal of Zoology ◽

10.1111/jzo.12868 ◽

2021 ◽

Author(s):

S. M. Xirouchakis ◽

C. Grivas ◽

G. Andreou ◽

E. Georgopoulou

Keyword(s):

Home Range ◽

Resource Selection ◽

Space Use ◽

Home Range Size ◽

Range Size ◽

Selection Of

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Does the punishment fit the crime? Consequences and diagnosis of misspecified detection functions in Bayesian spatial capture-recapture modelling

10.1101/2021.01.12.426298 ◽

2021 ◽

Author(s):

Soumen Dey ◽

Richard Bischof ◽

Pierre P. A. Dupont ◽

Cyril Milleret

Keyword(s):

Home Range ◽

Space Use ◽

Relative Bias ◽

Diagnostic Tools ◽

List Type ◽

Detection Function ◽

Density Estimates ◽

Use Patterns ◽

Wide Range ◽

Capture Recapture

AbstractSpatial capture-recapture (SCR) is now used widely to estimate wildlife densities. At the core of SCR models lies the detection function, linking individual detection probability to the distance from its latent activity center. The most common function (half-normal) assumes a bivariate normal space use and consequently detection pattern. This is likely an oversimplification and misrepresentation of real-life animal space use patterns, but studies have reported that density estimates are relatively robust to misspecified detection functions. However, information about consequences of such misspecification on space use parameters (e.g. home range area), as well as diagnostic tools to reveal it are lacking.We simulated SCR data under six different detection functions, including the half-normal, to represent a wide range of space use patterns. We then fit three different SCR models, with the three simplest detection functions (half-normal, exponential and half-normal plateau) to each simulated data set. We evaluated the consequences of misspecification in terms of bias, precision and coverage probability of density and home range area estimates. We also calculated Bayesian p-values with respect to different discrepancy metrics to assess whether these can help identify misspecifications of the detection function.We corroborate previous findings that density estimates are robust to misspecifications of the detection function. However, estimates of home range area are prone to bias when the detection function is misspecified. When fitted with the half-normal model, average relative bias of 95% kernel home range area estimates ranged between −25% and 26% depending on the misspecification. In contrast, the half-normal plateau model (an extension of the half-normal) returned average relative bias that ranged between −26% and −4%. Additionally, we found useful heuristic patterns in Bayesian p-values to diagnose the misspecification in detection function.Our analytical framework and diagnostic tools may help users select a detection function when analyzing empirical data, especially when space use parameters (such as home range area) are of interest. We urge development of additional custom goodness of fit diagnostics for Bayesian SCR models to help practitioners identify a wider range of model misspecifications.

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Sex Differences in Space Use of Breeding Common Ravens in Western Marin County, California

The Condor ◽

10.1093/condor/106.3.529 ◽

2004 ◽

Vol 106 (3) ◽

pp. 529-539 ◽

Cited By ~ 1

Author(s):

Jennifer E. Roth ◽

John P. Kelly ◽

William J. Sydeman ◽

Mark A. Colwell

Keyword(s):

Sex Differences ◽

Home Range ◽

Space Use ◽

Home Range Size ◽

Range Size ◽

Food Sources ◽

Small Scale ◽

Corvus Corax ◽

Marin County ◽

Core Areas

Abstract We estimated core areas and home-range sizes and evaluated sex differences in home-range size, seasonal variation in movements, and space use for breeding Common Ravens (Corvus corax) in western Marin County, California. There were no significant interannual differences in average core area or average home-range size for either sex, although there were small-scale shifts in home-range use for 67% of females and 63% of males. There was no significant difference in home-range size between the sexes. Home-range size was positively correlated with distance to food source. Ravens traveled shorter distances from the nest during the incubation + nestling stage compared to other stages of the breeding season. Core areas were centered around nest sites and food sources, with significantly aggregated locations for 83% and 100% of females in 2000 and 2001, respectively. Males were more variable in their use of space, with significantly aggregated locations for 38% and 44% of males in 2000 and 2001, respectively. Individual variation in home-range size, movements, and space use was likely due to differences in the distribution of important food sources in the area. Diferencias Sexuales en la Utilización del Espacio en Corvus corax en el Oeste del Condado Marin, California Resumen. Estimamos los tamaños del área núcleo y rango de hogar y evaluamos las diferencias entre sexos en el tamaño del rango de hogar, variaciones estacionales de los movimientos y utilización del espacio en Corvus corax en el oeste del condado Marin, California. No hubo diferencias interanuales significativas en el área núcleo promedio ni en el rango de hogar promedio para ninguno de los sexos, aunque para el 67% de las hembras y el 63% de los machos hubo cambios de pequeña escala en el uso del rango de hogar. No hubo diferencias significativas en el tamaño de los rangos de hogar entre sexos. El tamaño del rango de hogar estuvo positivamente correlacionado con la distancia a la fuente de alimento. Los cuervos viajaron distancias más cortas desde el nido durante los períodos de incubación y de cría de polluelos en comparación con otros períodos durante la época reproductiva. Las áreas núcleo se centraron en los sitios de nidificación y las fuentes de alimento, con posiciones significativamente agregadas para el 83% y 100% de las hembras en 2000 y 2001, respectivamente. Los machos presentaron mayor variabilidad en la utilización del espacio, con posiciones significativamente agregadas para un 38% y 44% de los machos en el 2000 y 2001, respectivamente. Las variaciones individuales en el tamaño de los ámbitos de hogar, movimientos y uso del espacio fueron probablemente dadas por las diferencias en la distribución de los recursos alimenticios importantes en el área.

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Estimating jaguar (Panthera onca) density in a preserved coastal area of French Guiana

Mammalia ◽

10.1515/mammalia-2016-0150 ◽

2018 ◽

Vol 82 (2) ◽

pp. 188-192 ◽

Cited By ~ 3

Author(s):

Matthis Petit ◽

Thomas Denis ◽

Ondine Rux ◽

Cécile Richard-Hansen ◽

Rachel Berzins

Keyword(s):

Home Range ◽

Coastal Area ◽

French Guiana ◽

Scale Parameter ◽

Local Density ◽

Home Range Size ◽

Range Size ◽

Spatially Explicit ◽

Panthera Onca ◽

Capture Recapture

AbstractKnowledge of the jaguar population is needed in French Guiana that faces an increase of human-jaguar conflicts. We carried out a camera trap survey to assess jaguar local density and home range size in a preserved coastal area of French Guiana. We ran spatially explicit capture recapture (SECR) models. In our model, the scale parameterσ, that is linked to the home range size, was larger for males (σ=3.87±0.59 SE km) than for females (σ=2.33±0.30 SE km). The assessed jaguar density was 3.22±0.87 SE ind. 100 km−2, which should be considered as an optimal density in a French Guiana coastal area.

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Sexual and environmental variation in the space requirements of the Critically Endangered geometric tortoise, Psammobates geometricus

Amphibia-Reptilia ◽

10.1163/156853812x634071 ◽

2012 ◽

Vol 33 (2) ◽

pp. 185-197 ◽

Cited By ~ 9

Author(s):

Margaretha Hofmeyr ◽

Ulric van Bloemestein ◽

Brian Henen ◽

Craig Weatherby

Keyword(s):

Home Range ◽

Habitat Degradation ◽

Space Use ◽

Home Range Size ◽

Home Ranges ◽

Convex Polygons ◽

Wet Season ◽

Mating Opportunities ◽

Space Requirements ◽

Nesting Season

Psammobates geometricus has a limited distribution in the southwestern Cape, South Africa, where it occurs in small habitat fragments separated by agricultural and urban developments. Space use and its determining factors thus represent critical information for the effective conservation of this species. We used radiotelemetry and thread-trailing to study the movement patterns and space use of geometric tortoises over an annual cycle, and estimated home ranges with minimum convex polygons and fixed-kernel methods. Home range size of geometric tortoises showed large inter-individual variation, and for females, a positive relationship to body size. Females, the larger sex, had larger home ranges and mean daily displacements than males had. Female space use was high through most of the year, except in the wet season, when food was abundant, temperatures relatively low, and soft soils allowed easy nesting. Males used more space and displaced further in the non-nesting than nesting season, perhaps to optimise mating opportunities in the non-nesting season before females ovulate. Home ranges were more elongate and overlapped more in fallow fields than in natural vegetation, suggesting that habitat degradation alters home range structure. The space geometric tortoises used for their annual activities ranged from 1.02 to 44.85 ha. The large home ranges and effects of habitat degradation should influence the size of reserves, and the destiny of geometric tortoises in small habitat fragments.

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Mating strategies of Pampean mouse males

Animal Biology ◽

10.1163/157075612x634102 ◽

2012 ◽

Vol 62 (4) ◽

pp. 381-396 ◽

Cited By ~ 9

Author(s):

Florencia Bonatto ◽

Daniela Gomez ◽

Andrea Steinmann ◽

José Priotto

Keyword(s):

Body Size ◽

Sexual Dimorphism ◽

Home Range ◽

Space Use ◽

Home Range Size ◽

Mating Strategies ◽

Range Size ◽

Home Ranges ◽

Males And Females ◽

Akodon Azarae

Patterns of space use and sexual dimorphism are frequently used to infer mating systems. We examined body size and home range size and intra- and intersexual overlap degree in order to elucidate mating strategy of Akodon azarae males. We studied spacing patterns using 113 and 129 home ranges established by males and females, respectively, in four 0.25 ha enclosures during the breeding season. Significant differences between sexes in home range size and overlap degree were found. Male home ranges were always larger than those of females. We observed exclusive space use among males and among females. Considering only those males that shared their home ranges with females, average intersexual overlap value was about 50%. Males mainly overlap their home ranges with home ranges of two or three females. Significant differences in body size were found between males and females, with males being larger. We concluded that space use and sexual dimorphism in this species is consistent with patterns characteristic of polygynous rodents, and we propose a polygynous system in A. azarae.

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Space Use and Movement of Urban Bobcats

Animals ◽

10.3390/ani9050275 ◽

2019 ◽

Vol 9 (5) ◽

pp. 275 ◽

Cited By ~ 2

Author(s):

Julie Young ◽

Julie Golla ◽

John Draper ◽

Derek Broman ◽

Terry Blankenship ◽

...

Keyword(s):

Home Range ◽

Behavioral Plasticity ◽

Activity Patterns ◽

Space Use ◽

Home Range Size ◽

Range Size ◽

Lynx Rufus ◽

Urban Setting ◽

Home Range Overlap ◽

Range Overlap

Global urbanization is rapidly changing the landscape for wildlife species that must learn to persist in declining wild spacing, adapt, or risk extinction. Many mesopredators have successfully exploited urban niches, and research on these species in an urban setting offers insights into the traits that facilitate their success. In this study, we examined space use and activity patterns from GPS-collared bobcats (Lynx rufus) in the Dallas–Fort Worth metroplex, Texas, USA. We found that bobcats select for natural/agricultural features, creeks, and water ways and there is greater home-range overlap in these habitats. They avoid roads and are less likely to have home-range overlap in habitats with more roads. Home-range size is relatively small and overlap relatively high, with older animals showing both greater home-range size and overlap. Simultaneous locations suggest bobcats are neither avoiding nor attracted to one another, despite the high overlap across home ranges. Finally, bobcats are active at all times of day and night. These results suggest that access to natural features and behavioral plasticity may enable bobcats to live in highly developed landscapes.

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