Black-tailed deer distance sampling on Blakely Island (WA), 2007 - 2021
Data files
Mar 04, 2024 version files 54.11 KB
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Data_files.xlsx
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README.md
Abstract
Removal of predators and creation of early seral habitat has, in many systems, caused substantial population growth of herbivores. Hyperabundant herbivores, in turn, induce cascading ecosystem effects, but few studies have investigated long-term browser density trends in relation to succession and stochastic climate events. Here, for the first time, we use annual population estimates of a forest browser to relate forest succession to the long-term decline of an herbivore that prefers early seral habitat. From 2007 – 2021, concurrent with reduced timber harvest, we used line-transect distance sampling to document annual changes in Columbian black-tailed deer (Odocoileus hemionus columbianus) density on a mid-sized (17.3km2) predator-free island. We documented successional changes associated with forest aggradation and decreased forage quality for deer: early successional shrub/scrub habitat declined 3.8%/year; timber volume increased 4.5%/year; and canopy coverage increased 2.5%. In 2007 – 2008, deer densities were the greatest observed (~44/km2), but then an historic snowstorm reduced deer density by 39%. Density increased slightly in 2010 but from 2010 – 2021, as forests matured, deer density decreased 4.0% per year, declining to 20 deer/km2. Despite declines, deer density on the island exceeds mainland densities, and overbrowsing likely continues to disrupt ecosystem processes.
README: Black-tailed deer distance sampling on Blakely Island (WA), 2007 - 2021
https://doi.org/10.5061/dryad.rfj6q57f0
The attached Excel file contains two sheets. The first worksheet contains used in population estimation of black-tailed on Blakely Island (WA). Each row corresponds to an observation of a deer, identifying the transect name, length, cluster size (i.e., # of deer seen together), and perpendicular distance from the transect to the deer (or centerpoint of the group). If a transect was surveyed and no deer were observed, the distance of the transect is included (so that sampling effort can be calculated), but cluster size and perpendicular distance are marked as "n/a." The second sheet contains historical landcover data on Blakely Island, pulled from CCAP.
Usage notes
The distance sampling data are formatted to be used in Program DISTANCE.