DOI: 10.5061/dryad.pv608
title: Data from: A mast-seeding desert shrub regulates population dynamics and behavior of its heteromyid dispersers

description: Granivorous rodent populations in deserts are primarily regulated through
 precipitation-driven resource pulses rather than pulses associated with
 mast-seeding, a pattern more common in mesic habitats. We studied
 heteromyid responses to mast-seeding in the desert shrub blackbrush
 (Coleogyne ramosissima), a regionally dominant species in the Mojave–Great
 Basin Desert transition zone. In a 5-year study at Arches National Park,
 Utah, USA, we quantified spatiotemporal variation in seed resources in
 mast and intermast years in blackbrush-dominated and mixed desert
 vegetation and measured responses of Dipodomys ordii (Ord's kangaroo
 rat) and Perognathus flavescens (plains pocket mouse). In
 blackbrush-dominated vegetation, blackbrush seeds comprised &gt;79% of
 seed production in a mast year, but 0% in the first postmast year.
 Kangaroo rat abundance in blackbrush-dominated vegetation was highest in
 the mast year, declined sharply at the end of the first postmast summer,
 and then remained at low levels for 3 years. Pocket mouse abundance was
 not as strongly associated with blackbrush seed production. In mixed
 desert vegetation, kangaroo rat abundance was higher and more uniform
 through time. Kangaroo rats excluded the smaller pocket mice from
 resource-rich patches including a pipeline disturbance and also moved
 their home range centers closer to this disturbance in a year of low
 blackbrush seed production. Home range size for kangaroo rats was
 unrelated to seed resource density in the mast year, but resource-poor
 home ranges were larger (P &lt; 0.001) in the first postmast year,
 when resources were limiting. Blackbrush seeds are higher in protein and
 fat but lower in carbohydrates than the more highly preferred seeds of
 Indian ricegrass (Achnatherum hymenoides) and have similar energy value
 per unit of handling time. Kangaroo rats cached seeds of these two species
 in similar spatial configurations, implying that they were equally valued
 as stored food resources. Blackbrush mast is a key resource regulating
 populations of kangaroo rats in this ecosystem.
description: Caching Trials, Willow
 FlatsEach record represents a
 single cache made by a kangaroo rat that had collected seeds at a bait
 tray in the field. Kangaroo rats were allowed to visit the tray multiple
 times within a trial. Fluorescent powder on the seeds aided the observer
 in locating the caches. Datum: WGS84Rodent Trapping, Salt
 ValleyEach record is a capture
 of a small mammal at Salt Valley, Arches National Park, Grand Co., Utah.
 Trapping was conducted in 15 sessions of 2 or 3 nights
 each.Rodent Trapping, Willow
 FlatsEach record is a capture
 of a small mammal at Willow Flats, Arches National Park, Grand Co., Utah.
 Trapping was conducted in 11 sessions of 2 or 3 nights
 each.Telemetry, Salt
 ValleyLocation records for
 radiocollared Ord's kangaroo rats in Salt Valley, Arches National
 Park, Grand Co., Utah.Telemetry, Willow
 FlatsLocation records for
 radiocollared Ord's kangaroo rats at Willow Flats, Arches National
 Park, Grand Co., Utah. Because sample sizes were fairly small, these data
 were combined with trapping data from the same time period and geographic
 area to produce utilization distributions for kangaroo rats. Trapping data
 were drawn from the companion data set "Rodent Trapping, Willow
 Flats.csv".Randomization procedure
 for niche overlapTo investigate possible
 competition between D. ordii and P. flavescens at Salt Valley, we
 calculated the observed niche overlap for all species–time period
 combinations. The 163 trap stations were considered the common resource,
 and we used the Czechanowski index (Feinsinger et al. 1981) as an estimate
 of niche overlap: 1.0 – 0.5 Ʃ │pi – ri│ where pi and ri represent the
 proportions of captures at trap station i for D. ordii and P. flavescens,
 respectively. We then used a randomization procedure with 1000 trials to
 generate a distribution of niche overlap matrices to which the observed
 values could be compared (True BASIC program, S. Jenkins). The procedure
 generated random numbers of captures at each trapping station for each
 species-time period combination while keeping fixed the values of (1) the
 total number of captures at each station over all species-period
 combinations and (2) the total number of captures for each species-period
 combination over all stations. We could then answer the question of
 whether there was more or less between-species niche overlap observed
 within time periods (1997, 1998, and 1999-2001) than expected by chance by
 examining the probability of the occurrence of the observed niche overlap
 values relative to the distribution of values generated by the
 randomization procedure.Randomization.csvFood Preference TrialsUsable trials in a cafeteria-style design to determine a heirarchy of preference for Ord's kangaroo rats (Dipodomys ordii) selecting to eat 4 seeds which occur at high frequencies in the plant community at Arches National Park, Grand Co., Utah: Coleogyne ramosissima, Ephedra viridis, Cowania mexicana, Wyethia scabra. Compositional analysis was used to determine preference heirarchy.Food Preference.csvHome Range Habitat Areas, Salt ValleyInputs for a test of the resource abundance hypothesis. We used the home range data for the mast year (1997) and the first post-mast year (1998) in separate analyses to examine the correlation between home range area and SMPA (seed mass per unit area). We also examined the effect of year on home range size and SMPA using ANOVA. Data were collected at Arches National Park, Grand Co., Utah.