Effects of Population Density On Patterns of Movement and Behavior of Gopher Tortoises (Gopherus polyphemus)

Guyer, Craig; Johnson, Valerie M.; Hermann, Sharon

doi:10.1655/herpmonographs-d-10-00004.1

Cited by 49 publications

(50 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Glen et al 2013); mechanical triggers (e.g. Guyer et al 2012); active infrared (AIR) sensors (e.g. Karanth et al 2006) and passive infrared (PIR) sensors (e.g.…”

Section: Introductionmentioning

confidence: 99%

How do passive infrared triggered camera traps operate and why does it matter? Breaking down common misconceptions

Welbourne

Claridge

Paull

et al. 2016

Remote Sens Ecol Conserv

View full text Add to dashboard Cite

The use of passive infrared (PIR) triggered camera traps has dramatically increased in recent decades. Unfortunately, technical descriptions of how PIR triggered camera traps operate have not been sufficiently clear. Descriptions have often been ambiguous or misleading and in several cases are demonstrably wrong. Such descriptions have led to erroneous interpretations of camera trapping data. This short communication clarifies how PIR sensors operate. We clarify how infrared radiation is emitted and transmitted, and we describe the parts of the PIR sensor and how they detect infrared radiation and, by extension, fauna. Several problematic descriptions of PIR sensors are drawn on to highlight flawed descriptions and demonstrate where erroneous interpretations of camera trapping data occurred. By clarifying the language and the description of PIR triggered camera traps, this paper ensures that wildlife researchers and managers using camera traps will avoid flawed interpretations of their data. Avoiding flawed interpretations of data should reduce wasted effort and resources that would otherwise come about as researchers attempt to test flawed hypotheses. Furthermore, this paper provides a thorough technical reference for camera trapping practitioners, which is not present elsewhere in the wildlife research literature.

show abstract

“…Glen et al 2013); mechanical triggers (e.g. Guyer et al 2012); active infrared (AIR) sensors (e.g. Karanth et al 2006) and passive infrared (PIR) sensors (e.g.…”

Section: Introductionmentioning

confidence: 99%

How do passive infrared triggered camera traps operate and why does it matter? Breaking down common misconceptions

Welbourne

Claridge

Paull

et al. 2016

Remote Sens Ecol Conserv

View full text Add to dashboard Cite

show abstract

“…This burrow density (, 3.5 ha 21 ) is comparable to highly suitable sites such as the Wade Tract in southern Georgia (Guyer et al 2012). Moran's I-values were less than ± 0.05 at all distance classes , 4 km and oscillated randomly around zero, indicating the absence of autocorrelation in the spatial distribution of the status of burrows (Fortin and Dale 2005).…”

Section: Resultsmentioning

confidence: 62%

“…We currently lack a complete understanding of the myriad of social and physical factors that lead to burrow abandonment by the gopher tortoise (Guyer et al 2012). The number of tortoise burrows always exceeds the number of resident tortoises; hence, a portion of the tortoise burrows will be abandoned as a normal outcome of tortoise behavior.…”

Section: Discussionmentioning

confidence: 99%

“…-Assessment of tortoise burrow features is necessary to determine use and occupancy of habitat at large extents because gopher tortoises spend approximately 90% of their time underground (McCoy et al 2006;Castellón et al 2012;Guyer et al 2012). The validity and repeatability of gopher tortoise population studies rests on the way burrows are classified (Smith et al 2005 and references therein).…”

Section: Studymentioning

confidence: 99%

“…When local conditions become unsuitable, gopher tortoises abandon their burrows. Although we currently lack a complete understanding of the social and environmental factors that cause tortoises to abandon or reoccupy burrows (Guyer et al 2012), vegetation structural change is the most well-documented driver of this response in forested ecosystems.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Sample Grain Influences the Functional Relationship Between Canopy Cover and Gopher Tortoise (Gopherus polyphemus) Burrow Abandonment

Catano

Angelo

Stout

2014

Chelonian Conservation and Biology

View full text Add to dashboard Cite

Change in vegetation structure alters habitat suitability for the threatened gopher tortoise (Gopherus polyphemus). An understanding of this dynamic is crucial to inform habitat and tortoise management strategies. However, it is not known how the choice of the sample grain (i.e., cell size) at which vegetation structure is measured impacts estimates of tortoise-habitat relationships. We used lidar remote sensing to estimate canopy cover around 1573 gopher tortoise burrows at incrementally larger sample grains (1-707 m 2 ) in 450 ha of longleaf pine (Pinus palustris) savanna. Using an information theoretic approach, we demonstrate that the choice of grain size profoundly influences modeled relationships between canopy cover and burrow abandonment. At the most supported grain size (314 m 2 ), the probability of burrow abandonment increased by 1.7% with each percent increase in canopy cover. Ultimately, detecting the appropriate sample grain can lead to more effective development of functional relationships and improve predictive models to manage gopher tortoise habitats.

show abstract

Interactions between density, home range behaviors, and contact rates in the Channel Island fox (Urocyon littoralis)

Sánchez

Hudgens²

2015

Ecology and Evolution

View full text Add to dashboard Cite

Many of the mechanisms underlying density-dependent regulation of populations, including contest competition and disease spread, depend on contact among neighboring animals. Understanding how variation in population density influences the frequency of contact among neighboring animals is therefore an important aspect to understanding the mechanisms underlying, and ecological consequences of, density-dependent regulation. However, contact rates are difficult to measure in the field and may be influenced by density through multiple pathways. This study explored how local density affects contact rates among Channel Island foxes (Urocyon littoralis) through two pathways: changes in home range size and changes in home range overlap. We tracked 40 radio-collared foxes at four sites on San Clemente Island, California. Fox densities at the four sites ranged from 2.8 ± 1.28 to 42.8 ± 9.43 foxes/km2. Higher fox densities were correlated with smaller home ranges (R2 = 0.526, F1,38 = 42.19, P < 0.001). Thirty foxes wore collars that also contained proximity loggers, which recorded the time and duration of occasions when collared foxes were within 5 m of one another. Contact rates between neighboring fox dyads were positively correlated with home range overlap (R2 = 0.341, P = 0.008), but not fox density (R2 = 0.012, P = 0.976). Individuals at high densities had more collared neighbors with overlapping home ranges (R2 = 0.123, P = 0.026) but not an increase in the amount of contact between individual neighbors. This study was the first time contact rates were directly measured and compared to density and home range overlap. Results suggest that foxes exhibit a threshold in their degree of tolerance for neighbors, overlap is a reliable index of the amount of direct contact between island foxes, and disease transmission rates will likely scale with fox density.

show abstract

Effects of Population Density On Patterns of Movement and Behavior of Gopher Tortoises (Gopherus polyphemus)

Cited by 49 publications

References 21 publications

How do passive infrared triggered camera traps operate and why does it matter? Breaking down common misconceptions

How do passive infrared triggered camera traps operate and why does it matter? Breaking down common misconceptions

Sample Grain Influences the Functional Relationship Between Canopy Cover and Gopher Tortoise (Gopherus polyphemus) Burrow Abandonment

Interactions between density, home range behaviors, and contact rates in the Channel Island fox (Urocyon littoralis)

Contact Info

Product

Resources

About