Does estimator choice influence our ability to detect changes in home-range size?

Signer, Johannes; Balkenhol, Niko; Ditmer, Mark A.; Fieberg, John

doi:10.1186/s40317-015-0051-x

Cited by 32 publications

(30 citation statements)

References 30 publications

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“…Hence, we took the option to run asymptote analyses and to evaluate the accuracy of estimates obtained with different data sets (Girard et al 2002;Börger 2006). Our models provide further evidence that the sampling effort affects estimates of the territory size evaluated with MCP, as previously highlighted in other species (Powell 2000;Girard et al 2002;Signer et al 2015).…”

Section: Effect Of the Sampling Effort And Territory Sizesupporting

confidence: 80%

Territory exclusivity and intergroup encounters in the indris (Mammalia: Primates: Indridae: Indri indri) upon methodological tuning

Bonadonna

Torti

Sorrentino

et al. 2017

The European Zoological Journal

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Territorial, socially monogamous species actively defend their home range against conspecifics to maintain exclusive access to resources such as food or mates. Primates use scent marks and loud calls to signal territory occupancy and limit the risk of intergroup encounters, maximizing their energetic balance. Indri indri is a little-studied territorial, socially monogamous singing primate living in family groups. The groups announce territory occupancy with long-distance calls, and actively defend their territories from conspecific intruders. This work includes data collected in three forests in Madagascar on 16 indri groups over up to 5 years. We aimed (1) to estimate the extent of territories using minimum convex polygon (MCP), implementing minimum sampling effort requirements; (2) to quantify territorial exclusivity, measuring the overlap between territories; and (3) to evaluate the intergroup encounter rate and to quantify the dynamics of group encounters. Our results showed that indris range evenly within exclusive small territories with no or little overlap. Intergroup encounters are rare (0.05 encounters per day), and are located on the periphery of the territories. Disputes were mostly solved with vocal confrontation and only in 13% of the cases ended in physical fights. This frame underlines a cost-benefit explanation of territoriality, favouring a strategy that efficiently limits overlap and avoids costly intergroup encounters. We hypothesize that territorial behaviour in indri is related to mate-guarding strategy and that vocal behaviour plays a fundamental role in regulating intergroup spacing dynamics.

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Section: Effect Of the Sampling Effort And Territory Sizesupporting

confidence: 80%

Territory exclusivity and intergroup encounters in the indris (Mammalia: Primates: Indridae: Indri indri) upon methodological tuning

Bonadonna

Torti

Sorrentino

et al. 2017

The European Zoological Journal

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“…, Signer et al. ), but the precise conditions under which autocorrelation and movement behavior can a priori be expected to influence these thresholds have remained obscure.…”

Section: Introductionmentioning

confidence: 99%

A comprehensive analysis of autocorrelation and bias in home range estimation

Noonan

Tucker

Fleming

et al. 2019

Ecological Monographs

170

231

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Home range estimation is routine practice in ecological research. While advances in animal tracking technology have increased our capacity to collect data to support home range analysis, these same advances have also resulted in increasingly autocorrelated data. Consequently, the question of which home range estimator to use on modern, highly autocorrelated tracking data remains open. This question is particularly relevant given that most estimators assume independently sampled data. Here, we provide a comprehensive evaluation of the effects of autocorrelation on home range estimation. We base our study on an extensive data set of GPS locations from 369 individuals representing 27 species distributed across five continents. We first assemble a broad array of home range estimators, including Kernel Density Estimation (KDE) with four bandwidth optimizers (Gaussian reference function, autocorrelated‐Gaussian reference function [AKDE], Silverman's rule of thumb, and least squares cross‐validation), Minimum Convex Polygon, and Local Convex Hull methods. Notably, all of these estimators except AKDE assume independent and identically distributed (IID) data. We then employ half‐sample cross‐validation to objectively quantify estimator performance, and the recently introduced effective sample size for home range area estimation (normalNfalse^area) to quantify the information content of each data set. We found that AKDE 95% area estimates were larger than conventional IID‐based estimates by a mean factor of 2. The median number of cross‐validated locations included in the hold‐out sets by AKDE 95% (or 50%) estimates was 95.3% (or 50.1%), confirming the larger AKDE ranges were appropriately selective at the specified quantile. Conversely, conventional estimates exhibited negative bias that increased with decreasing normalNfalse^area. To contextualize our empirical results, we performed a detailed simulation study to tease apart how sampling frequency, sampling duration, and the focal animal's movement conspire to affect range estimates. Paralleling our empirical results, the simulation study demonstrated that AKDE was generally more accurate than conventional methods, particularly for small normalNfalse^area. While 72% of the 369 empirical data sets had >1,000 total observations, only 4% had an normalNfalse^area >1,000, where 30% had an normalNfalse^area <30. In this frequently encountered scenario of small normalNfalse^area, AKDE was the only estimator capable of producing an accurate home range estimate on autocorrelated data.

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“…95% kernel density estimator [18]) are more in accordance with the original definition [14], excluding movement patterns such as exploratory behaviour from an individual's home range. Although choice of home range estimator may affect estimates of home range size, several studies suggest that home range estimators can provide valuable information about variation in animal space use [18][19][20][21][22], and that variation in estimated home range size owing to methodological differences is weaker than ecological signals with no qualitative influence on conclusions regarding ecological patterns ( [23,24], but see [25]). Accordingly, knowledge about factors generating variation in home range size among populations and species may provide valuable information about the underlying ecological processes affecting intra-and interspecific variation in space use [26,27].…”

Section: Introductionmentioning

confidence: 99%

Home ranges, habitat and body mass: simple correlates of home range size in ungulates

et al. 2016

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The spatial scale of animal space use, e.g. measured as individual home range size, is a key trait with important implications for ecological and evolutionary processes as well as management and conservation of populations and ecosystems. Explaining variation in home range size has therefore received great attention in ecological research. However, few studies have examined multiple hypotheses simultaneously, which is important provided the complex interactions between life history, social system and behaviour. Here, we review previous studies on home range size in ungulates, supplementing with a meta-analysis, to assess how differences in habitat use and species characteristics affect the relationship between body mass and home range size. Habitat type was the main factor explaining interspecific differences in home range size after accounting for species body mass and group size. Species using open habitats had larger home ranges for a given body mass than species using closed habitats, whereas species in open habitats showed a much weaker allometric relationship compared with species living in closed habitats. We found no support for relationships between home range size and species diet or mating system, or any sexual differences. These patterns suggest that the spatial scale of animal movement mainly is a combined effect of body mass, group size and the landscape structure. Accordingly, landscape management must acknowledge the influence of spatial distribution of habitat types on animal behaviour to ensure natural processes affecting demography and viability of ungulate populations.

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Does estimator choice influence our ability to detect changes in home-range size?

Cited by 32 publications

References 30 publications

Territory exclusivity and intergroup encounters in the indris (Mammalia: Primates: Indridae: Indri indri) upon methodological tuning

Territory exclusivity and intergroup encounters in the indris (Mammalia: Primates: Indridae: Indri indri) upon methodological tuning

A comprehensive analysis of autocorrelation and bias in home range estimation

Home ranges, habitat and body mass: simple correlates of home range size in ungulates

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