Skip to main content
Dryad logo

Drought and coyotes mediate mesopredator response to human disturbance

Citation

Parren, Molly (2021), Drought and coyotes mediate mesopredator response to human disturbance, Dryad, Dataset, https://doi.org/10.5061/dryad.6t1g1jx08

Abstract

Mesopredators in western North America are facing major changes to their ecosystems, including drought and the expansion of human disturbance. To balance resource needs and risk-taking on the landscape, mesopredators are likely shifting their habitat use as well as their interspecies interactions. As part of a large-scale study to help evaluate responses of terrestrial wildlife to severe drought, the California Department of Fish and Wildlife surveyed mesopredator presence across 585 sites in the Mojave Desert and Central Valley ecoregions of California. This study spanned a drought year (2016) and a post-drought year (2017), providing the opportunity to investigate how drought and interspecific interactions may mediate spatial patterns of mesopredator occurrence across a continuum of human disturbance levels. We used single-season, single-species, and conditional two-species occupancy models to elucidate these relationships in both ecoregions. We examined occupancy and detection of coyotes (Canis latrans) and smaller mesopredators, including bobcats (Lynx rufus) in both ecoregions, raccoons (Procyon lotor) in the Central Valley, and desert kit foxes in the Mojave Desert (Vulpes macrotis arsipus). The presence of coyotes influenced the detection probability of all other mesopredator species, and the impacts of drought varied by species and ecoregion. Detection of mesopredators in the Central Valley was typically higher in 2016, especially at low disturbance sites, suggesting species may have become more active during the drought to meet resource needs. However, detection of mesopredators in the Mojave Desert tended to increase after the drought, suggesting a response to an increase in resources (e.g., prey). Coyotes in the Mojave Desert became more detectable in high human disturbance in 2016 and less detectable in 2017, possibly increasing activity during the drought in human-disturbed areas to obtain anthropogenic resources. Drought not only affects individual species and their relationships to human disturbance, but it can also impact their interspecies interactions and use of different landscape features.

Methods

This data represents presence/absence data for mesopredators based on camera trap surveys conducted at 266 sites in the Central Valley and 319 sites in the Mojave Desert of California in 2016 and 2017. Additional data included are non-standardized covariate values and real parameter estimates from occupancy modeling for mesopredators for scenarios of interest involding drought and human disturbance. 

Usage Notes

There are separate detection histories for each individual mesopredator species in both ecoregions and then combined detection histories for coyotes and subordinate mesopredator species in both ecoregions.

Detection history: 1 = species detected on this survey (survey = single day in Central Valley and within a 3-day survey period in Mojave Desert), 0 = species not detected during survey, NA = camera non-functional during survey (camera not aimed at bait for 24 hrs, likely due to disturbance to the camera). These detection histories are followed by standardized values for covariates

In two species files (CANLAT & other species code)  the two detection histories are combined, with the subordinate species (not coyote) coming first (column 1 = survey 1 for subordinate species, column 2 = survey 1 for coyote, column 3 = survey 2 for subordinate species, column 4 = survey 2 for coyotes, etc.).

Covariates are standardized in detection histories so CV (Central Valley) and MD (Mojave Desert) covariates are included for raw covariate values. Did not include lag for coyote or bait for MD in the raw covariates (bait is just sequential from 1 and lag is same in standardized values).

OVERALL KEY

MD = Mojave Desert

CV = Central Valley

CANLAT = Coyote (Canis latrans)

LYNRUF = Bobcat (Lynx rufus)

VULMAC = Kit fox (Vulpes macrotis)

PROLOT = Raccoon (Procyon lotor)

CV covariates:

lat = latitude

yr =  year (0 = 2016, 1 = 2017)

HD = measure of human disturbance (1-10) within a 1 km buffer of the camera at a site

trees = proportion tree cover (including orchards) within a 1 km buffer of camera at a site

water = water at site at time of camera deployment(1 = yes, 0 = no)

d_water = distance to water (km)

yr*HD = interaction with year

yr*water = interaction of presence of water at a site with year 

yr*d_water = interaction of distance to water at site with year

j(1-27) = ordinal date on day of survey (e.g. j1 = ordinal date on first survey)

From detection history:

3lag(1-27) = CV coyote Markov dependency (= 1 if coyote detected in past 3 days)

MD covariates:

elev = elevation (km)

water = distance to water (km)

HD = measure of human disturbance (1-10) within a 1 km buffer of the camera at a site

YR = year (0 = 2016, 1 = 2017)

guzz = presence of guzzler at site (1 = guzzler on site, 0 = guzzler not on site)

julian1 = ordinal date on day of first survey

YR*HD = interaction of human disturbance at site with year

YR*guzz = interaction of presence of guzzler at a site with year 

YR*water = interaction of distance to water at site with year

From detection history:

b(1-9) = standardized bait day (same as day of survey = age of bait)

Single/Two Species Parameter Estimates:

Parameter

Single

  • p = detection probability
  • Psi = occupancy probability

Two

  • PsiA = occupancy probability of species A (coyote)
  • PsiBA = occupancy probability of species B (subordinate species: bobcat, raccoon, or kit fox) if species A is present (same as PsiBa)
  • PsiBa = occupancy probability of species B (subordinate species: bobcat, raccoon, or kit fox) if species A is absent (same as PsiBA)
  • pA = detection probability of species A (coyote) is species B is absent (same as rA)
  • rA = detection probability of species A (coyote) if both species are present (same as pA)
  • pB = detection probability of species B if species A is absent  
  • rBA = detection probability of species B if species A is present and detected (same as rBa)
  • rBa = detection probability of species B if species A is present and not detected (same as rBA)

Human Disturbance: Measure (1-10) of human disturbance (footprint) within 1 km buffer of site

Central Valley

  • Low = 4
  • Average =  8.1
  • High = 10

Mojave Desert

  • Low = 1
  • Average = 3.4
  • High = 6.8

SE: Standard Error

LCI = lower 95% confidence interval 

UCI = upper 95% confidence interval 

From two species:

Sub. species = subordinate species, species B (dominant species is always the coyote, Species A)

Funding

California Department of Fish and Wildlife