scholarly journals Estimating densities for sympatric kit foxes (Vulpes macrotis) and coyotes (Canis latrans) using noninvasive genetic sampling

2018 ◽  
Vol 96 (10) ◽  
pp. 1080-1089 ◽  
Author(s):  
R.C. Lonsinger ◽  
P.M. Lukacs ◽  
E.M. Gese ◽  
R.N. Knight ◽  
L.P. Waits
Keyword(s):  
Great Basin ◽  
Canis Latrans ◽  
Density Estimates ◽  
Intraguild Interactions ◽  
Noninvasive Genetic Sampling ◽  
Kit Fox ◽  
Genetic Sampling ◽  
Vulpes Macrotis ◽  
Capture Recapture ◽  
Precipitous Decline

Kit fox (Vulpes macrotis Merriam, 1888) populations in the Great Basin Desert have declined and are of increasing concern for managers. Increasing coyote (Canis latrans Say, 1823) abundance and subsequent intraguild interactions may be one cause for this decline. Concurrent monitoring of carnivores is challenging and therefore rarely conducted. One possible solution for monitoring elusive carnivores is using noninvasive genetic sampling. We used noninvasive genetic sampling to collect fecal DNA from kit foxes and coyotes and estimate their densities from 2013–2014 in Utah, USA. We identified individuals based on microsatellite genotypes and estimated density with multisession spatially explicit capture–recapture models. Mean kit fox density was 0.02 foxes·km−2, while coyote densities were up to four times greater (0.07–0.08 coyotes·km−2). Kit fox densities were significantly lower than densities in the 1950s but were comparable with estimates from the late 1990s, suggesting that populations may be stabilizing after a precipitous decline. Our kit fox density estimates were among the lowest documented for the species. Our coyote density estimate was the first reported in our region and revealed that despite seemingly high abundance, densities are low compared with other regions. Our results suggested that kit foxes may be able to coexist with coyotes.

scholarly journals Resource partitioning between kit foxes (Vulpes macrotis) and coyotes (Canis latrans): a comparison of historical and contemporary dietary overlap

2018 ◽  
Vol 96 (5) ◽  
pp. 497-504 ◽  
Author(s):  
P.A. Byerly ◽  
R.C. Lonsinger ◽  
E.M. Gese ◽  
A.J. Kozlowski ◽  
L.P. Waits
Keyword(s):  
Great Basin ◽  
Native Species ◽  
Dietary Diversity ◽  
Canis Latrans ◽  
Population Level ◽  
Relative Importance ◽  
Dietary Overlap ◽  
Kit Fox ◽  
Prey Diversity ◽  
Vulpes Macrotis

Range expansions by generalists can alter communities and introduce competitive pressures on native species. In the Great Basin Desert, USA, coyotes (Canis latrans Say, 1823) have colonized and are now sympatric with native kit foxes (Vulpes macrotis Merriam, 1888). Since both species have similar diets, dietary partitioning may facilitate coexistence. We analyzed coyote and kit fox diets, then compared our results to an earlier study. Because populations are dynamic, we expected that decreases in prey or increases in predator abundance could alter dietary patterns. We found no significant changes in population-level prey diversity for kit foxes or coyotes, but found high levels of dietary overlap between species. We did detect a significant decrease in the relative importance of leporids (family Leporidae) in the diets of both canids, but they remained important for coyotes. The relative importance of small mammals was greater for kit foxes than coyotes, but their importance had not changed significantly over time. We detected significant declines in prey diversity per sample (scat-level dietary diversity) for both canids, suggesting that during a foraging event, individuals may encounter less diverse prey now than historically. These findings suggested that kit foxes and coyotes were not limited by prey, despite high dietary overlap.

scholarly journals Characteristics of current and historical kit fox (Vulpes macrotis) dens in the Great Basin Desert

2003 ◽  
Vol 81 (1) ◽  
pp. 96-102 ◽  
Author(s):  
Wendy M Arjo ◽  
Tim J Bennett ◽  
Adam J Kozlowski
Keyword(s):  
Home Range ◽  
Great Basin ◽  
Geographical Area ◽  
Home Range Size ◽  
Physical Characteristics ◽  
Range Size ◽  
Multiple Use ◽  
Mountainous Areas ◽  
Kit Fox ◽  
Vulpes Macrotis

We examined the ecological and physical characteristics of den sites for 13 adult kit fox (Vulpes macrotis) in western Utah from December 1998 to February 2001. We also compared current and historical den distribution among habitat types. The number of den sites used was not influenced by home-range size (P = 0.11) or season (P = 0.40), but was influenced by geographical area. Home-range size was smallest (P = 0.007) and the number of dens used was greatest (P = 0.009) in mountainous areas. Ecological and physical characteristics of single-use dens (n = 30) were compared with those of multiple-use (n = 53) and natal dens (n = 8). Characteristics that differed between den types included number of entrances (P = 0.0001), diameter of entrances (P = 0.003), and height of vegetation along transects (P = 0.0001). Natal den entrance azimuths were weighted towards a northwesterly aspect (P = 0.0022); however, single- and multiple-use den exits appeared to be randomly distributed. Historical changes in kit fox den site selection have occurred since 1959 (P < 0.0001). We characterized more dens in invasive grasslands and fewer in greasewood (Sarcobatus vermiculatus) habitats than previously described. The conversion of native habitat to grassland and the increase in coyote population may have altered kit fox distribution to include mountainous areas not previously described.

scholarly journals Carnivora atnd their larger mammalian prey species invenory and abundance in the Janos-Nuevo Casas Grandes praire dog complex, Chihuahua.

2014 ◽  
Vol 3 (1) ◽  
pp. 95 ◽  
Author(s):  
Rurik H. List Sánchez ◽  
David W. Macdonald
Keyword(s):  
Canis Latrans ◽  
Prairie Dog ◽  
Casas Grandes ◽  
Kangaroo Rats ◽  
Taxidea Taxus ◽  
Kit Fox ◽  
Carnivore Species ◽  
Vulpes Macrotis ◽  
Lepus Californicus ◽  
North Western

Abstract. This study examined the carnivore species composition and abundance in the Janos-Nuevo Casas Grandes prairie dog complex of north-western Chihuahua, Mexico. Thirteen species of carnivores were recorded in habitats including prairie dog towns, grassland, mesquite scrub and riparian vegetation. From artificial scent-stations and spotlight transects the most abundant carnivore species appeared to be the kit fox Vulpes macrotis and the coyote Canis latrans. Striped/hooded skunks (Mephitis spp) and American badgers (Taxidea taxus) were also common. No significant differences were found between the abundance of kit foxes or coyotes on prairie dog towns or grassland; but skunks were more abundant on grasslands. The abundance of hares (Lepus californicus), rabbit (Sylvilagus audubonii), and kangaroo rat (Dipodomys spp) was also estimated; hares and kangaroo rats were more abundant in the grassland, whilst rabbits were more abundant in prairie dog towns.Resumen. Se estudió la composición de espeices de carnívoros en el complejo de perros llaneros Janos-Nuevo Casas Grandes, en el noroeste de Chihuahua, México. Se registraron 13 especies de carnívoros en los siguientes hábitats; colonias de perros lIaneros, pastizal, matorral de mezquite y vegetación riparia. Por medio de estaciones olfativas y transectos de lampareo se determinó que la zorra norteña Vulpes macrotis y el coyote Canis latrans fueron los más abundantes. Los zorrillos (Mephitis spp) y tejones (Taxidea taxus) también fueron comunes. No se encontraron diferencias significativas en la abundancia de zorras norteñas o coyotes entre colonias de perros llaneros o pastizal. Los zorrillos fueron más abundantes en el pastizal. También se estimó la abundancia de liebres (Lepus californicus), conejos (Sylvilagus audubonii), y ratas canguro (Dipodomys spp); las liebres y ratas canguro son más abundantes en el pastizal, mientras los conejos son mas abundantes en las colonias de perros lIaneros.Key words: Carnivore abundance, Chihuahua, Mexico, prairie dog, scent-station, spotlighting.

A factorial design experiment as a pilot study for noninvasive genetic sampling

2012 ◽  
Vol 12 (6) ◽  
pp. 1040-1047 ◽  
Author(s):  
SHARON RENAN ◽  
EDITH SPEYER ◽  
NAAMA SHAHAR ◽  
TOMER GUETA ◽  
ALAN R. TEMPLETON ◽  
...  
Keyword(s):  
Pilot Study ◽  
Factorial Design ◽  
Design Experiment ◽  
Noninvasive Genetic Sampling ◽  
Genetic Sampling ◽  
Factorial Design Experiment

scholarly journals Empirical comparisons of abundance estimators for two sympatric carnivores using noninvasive genetic sampling

2019 ◽  
Vol 2019 (1) ◽  
Author(s):  
Robert C. Lonsinger ◽  
Paul M. Lukacs ◽  
Eric M. Gese ◽  
Lisette P. Waits
Keyword(s):  
Noninvasive Genetic Sampling ◽  
Genetic Sampling ◽  
Sympatric Carnivores

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

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.

scholarly journals Density Estimates of Unmarked Large Mammals at Camera Traps Vary among Models, Species, and Years, Signalling Importance of Model Assumptions

2021 ◽  
Author(s):  
Jason Fisher ◽  
Joanna Burgar ◽  
Melanie Dickie ◽  
Cole Burton ◽  
Rob Serrouya
Keyword(s):  
Density Estimation ◽  
Black Bear ◽  
Camera Traps ◽  
Mammal Species ◽  
Density Estimates ◽  
Movement Rates ◽  
Social Species ◽  
Marked Variability ◽  
Capture Recapture ◽  
Best Fitting

Density estimation is a key goal in ecology but accurate estimates remain elusive, especially for unmarked animals. Data from camera-trap networks combined with new density estimation models can bridge this gap but recent research has shown marked variability in accuracy, precision, and concordance among estimators. We extend this work by comparing estimates from two different classes of models: unmarked spatial capture-recapture (spatial count, SC) models, and Time In Front of Camera (TIFC) models, a class of random encounter model. We estimated density for four large mammal species with different movement rates, behaviours, and sociality, as these traits directly relate to model assumptions. TIFC density estimates were typically higher than SC model estimates for all species. Black bear TIFC estimates were ~ 10-fold greater than SC estimates. Caribou TIFC estimates were 2-10 fold greater than SC estimates. White-tailed deer TIFC estimates were up to 100-fold greater than SC estimates. Differences of 2-5 fold were common for other species in other years. SC estimates were annually stable except for one social species; TIFC estimates were highly annually variable in some cases and consistent in others. Tests against densities obtained from DNA surveys and aerial surveys also showed variable concordance and divergence. For gregarious animals TIFC may outperform SC due to the latter model’s assumption of independent activity centres. For curious animals likely to investigate camera traps, SC may outperform TIFC, which assumes animal behavior is unaffected by cameras. Unmarked models offer great possibilities, but a pragmatic approach employs multiple estimators where possible, considers the ecological plausibility of assumptions, and uses an informed multi-inference approach to seek estimates from models with assumptions best fitting a species’ biology.

Sign in / Sign up

Export Citation Format

Share Document