DOI: 10.6073/pasta/bfd1a4f51b77614f21a1511c4f15da0c
title: Pika habitat occupancy survey data for Niwot Ridge and Green Lakes Valley, 2016 - ongoing

description: Long-term monitoring of habitat occupancy can reveal patterns of
 habitat use, population dynamics, and factors controlling species
 distribution. The American pika (Ochotona princeps), a small mammal
 found in rocky habitats throughout western North America, has been
 targeted for occupancy studies due to its relatively conspicuous
 behavior and its unusual adaptations for surviving long, cold
 winters without hibernation. These adaptations include an unusually
 high resting metabolic rate and maintenance of body temperatures
 near the lethal maximum for this species, which would appear to
 compromise the pika's ability to survive warmer summers. Recent
 monitoring as well as projections based on future climate scenarios
 have suggested this species is experiencing a period of range
 retraction due to warming summers and/or loss of insulating winter
 snow cover. Niwot Ridge is situated ideally to test competing
 hypotheses about the trajectory and drivers of pika range shift. The
 pika is still common throughout the Colorado Rockies, but published
 models differ markedly regarding projections of the pika’s future
 distribution in this region. Niwot Ridge has experienced warmer
 summers as well as shorter periods of insulating snow cover in
 recent years, and there is evidence that pikas are now less common
 than they once were in at least one area on the ridge. This study is
 designed to provide robust data on pika population trends through
 long-term monitoring of occupancy in a spatially balanced random
 sample of pika habitat patches centered on Niwot Ridge. Survey plots
 (n = 72) were selected according to a Generalized
 Random-Tessellation Stratified (GRTS) algorithm, stratified
 dichotomously by elevation, average annual snow accumulation (SWE),
 and probabilities of pika occurrence based on previous data. Each
 plot extends 12 m in radius from a GRTS point. To ensure that each
 plot contains at least 10% cover of talus, plot coordinates were
 adjusted (usually less than 50 m) or replaced using the GRTS
 oversample to select the next available and suitable plot within the
 same categories of elevation, SWE and probability of occurrence (see
 "pika-survey-GRTS-plot-tracking-record.cr.data.csv" for
 plot strata, survey schedules, GRTS sequence, and records of plot
 replacement or location adjustments). Trained technicians survey
 plots for pikas and fresh pika sign (food caches and fecal pellets)
 as well as metrics of habitat quality. Each year, 48 of the 72 plots
 are surveyed in a rotating panel design (24 plots are surveyed
 annually, 24 in even years and 24 in odd years). Plots are surveyed
 in August when pikas are engaged in food caching and other
 conspicuous behaviors related to territory establishment and
 defense. Data collected at each plot are detailed in a survey manual
 ("pika_survey.cr.methods.docx"). Each plot is outfitted
 with a data logger (sensor) to record sub-surface temperature
 several times each day. Photos of plot and sensor locations are used
 in navigation and sensor retrieval. Each survey is completed during
 a brief (half-hour) visit to the plot to service the sensor and to
 record habitat and pika data. A subset of plots (n = 12) are
 selected for double surveys each year to allow estimation of pika
 detection probability. Estimates of detection probability are also
 informed by data on time to detection of pikas and pika sign
 recorded during each survey. Samples of fresh pika fecal pellets are
 collected from occupied plots and are stored as vouchers of pika
 presence and for use in studies of population genetics and
 physiology, including studies of physiological stress in relation to
 habitat quality and microclimate.