10.5061/DRYAD.ZPC866TBZ
Riecke, Thomas
0000-0001-7998-5233
Swiss Ornithological Institute
Lohman, Madeleine
University of Nevada Reno
Sedinger, Ben
University of Wisconsin System
Arnold, Todd
University of Minnesota
Koons, David
Colorado State University
Feldheim, Cliff
California Trout
Rohwer, Frank
Delta Waterfowl Foundation
Schaub, Michael
Swiss Ornithological Institute
Williams, Perry
University of Nevada Reno
Sedinger, James
University of Nevada Reno
Data from: Density-dependence produces spurious relationships among
demographic parameters in a harvested species
Dryad
dataset
2022
FOS: Biological sciences
blue-winged teal
Density-dependence
harvest compensation
integrated population model
multicollinearity
Population dynamics
Spatula discors
survival
Delta Waterfowl Foundation
https://ror.org/01ezjqh37
2022-08-24T00:00:00Z
2022-08-24T00:00:00Z
en
https://doi.org/10.5281/zenodo.7036551
339196 bytes
3
CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
1. Harvest of wild organisms is an important component of human culture,
economy, and recreation, but can also put species at risk of extinction.
Decisions that guide successful management actions therefore rely on the
ability of researchers to link changes in demographic processes to the
anthropogenic actions or environmental changes that underlie variation in
demographic parameters. 2. Ecologists often use population models or
maximum sustained yield curves to estimate the impacts of harvest on
wildlife and fish populations. Applications of these models usually focus
exclusively on the impact of harvest and often fail to consider adequately
other potential, often collinear, mechanistic drivers of the observed
relationships between harvest and demographic rates. In this study, we
used an integrated population model and long-term data (1973-2016) to
examine the relationships among hunting and natural mortality, the number
of hunters, habitat conditions, and population size of blue-winged teal
(Spatula discors), an abundant North American dabbling duck with a
relatively fast-paced life history strategy. 3. Over the last two and a
half decades of the study, teal abundance tripled, hunting mortality
probability increased slightly (< 0.02), and natural mortality
probability increased substantially (> 0.1) at greater population
densities. We demonstrate strong density-dependent effects on natural
mortality and fecundity as population density increased, indicative of
compensatory harvest mortality and compensatory natality. Critically, an
analysis that only assessed the relationship between survival and hunting
mortality would spuriously indicate depensatory hunting mortality due to
multicollinearity between abundance, natural mortality, and hunting
mortality. 4. Our findings demonstrate that models that only consider the
direct effect of hunting on survival or natural mortality can fail to
accurately assess the mechanistic impact of hunting on population dynamics
due to multicollinearity among demographic drivers. This multicollinearity
limits inference and may have strong impacts on applied management actions
globally.
Adult female blue-winged teal (n = 112,639) were captured in traps and
nets prior to the hunting season (July-September) in the prairie potholes
and aspen parklands of the North American midcontinent from 1973 to 2016
(Figure 1). Teal were ringed with uniquely engraved metal markers, and
some marked individuals were killed by hunters. A portion of these markers
were retrieved and reported to the USGS Bird Banding Lab (n = 2,518; USGS
Patuxent Wildlife Research Center). From 1974-2016, waterfowl breeding
population and habitat surveys were flown at the beginning of the breeding
season over the same area by the U.S. Fish and Wildlife Service and the
Canadian Wildlife Service to estimate the total number of breeding pairs
of teal (y_n,t) and other ducks, and the number of ponds (y_p,t), a
landscape scale measure of habitat suitability for breeding waterfowl
(Walker et al. 2013, U.S. Fish & Wildlife Service 2018). We
downloaded the ringing and recovery data from the GameBirds Database CD
(Bird Banding Lab, USGS Patuxent Wildlife Research Center), and the
Waterfowl Breeding Population and Habitat Survey data from the USFWS
Migratory Birds Data Center. We retained females marked in Canada and the
United States in Waterfowl Breeding Population and Habitat Survey strata
20-49 (U.S. Fish & Wildlife Service 2018), and we restricted
re-encounters to harvested individuals recovered and reported by hunters
in the United States and Canada from September through early February,
with half of all reported hunting mortality occurring in September. We
excluded recoveries in Mexico, Central and South America, and the
Carribean (n = 316) due to the inclusion of band reporting probabilities
(r = r_1973, ... , r_2016) in our analyses, which were not available for
Latin America. Mark-recovery data were downloaded from the USGS Bird
Banding Lab Celis-Murillo et al. 2020. We accessed estimates of teal
abundance and pond abundance from the Waterfowl Breeding Population and
Habitat Survey (U.S. Fish & Wildlife Service 2018), as well as
data on federal duck stamp sales, which are required to hunt for waterfowl
in the United States. Third party data were used for this study,
collection of which followed appropriate ethical guidelines. No additional
ethical approval was required from our respective insitutions. We
formatted the capture-recovery data into a multinomial array to reduce
computational requirements. Please contact the authors for additional
information about data processing.
The open-source programs R and JAGS are required to run the integrated
population model described in this manuscript.