Northern Yellowstone Elk survival and competing risks

Prey vulnerability to predation can vary by life history stage, and prey population stage structure determines the strength a predator species wields on their community. Prey population stage structure can vary over time, yet little is known about how temporal change in prey stage structure influences predator-prey interactions. We used data of wolves hunting adult female elk in Yellowstone National Park to demonstrate that stage-selective wolf predation of old individuals (>11 years old) was more additive than wolf predation of young individuals (2–11 years old). Additive predation of older elk coupled with an aging female elk population increased the strength of wolf predation over time. When vulnerable prey comprise an increasing proportion of a population, their early demise may decrease population growth. Accounting for temporal variation in predation risk across a prey population is therefore critical to understanding the community-level consequences of predator-prey interactions.Funding provided by: National Science FoundationCrossref Funder Registry ID: http://dx.doi.org/10.13039/100000001Award Number: DEB-0078130Funding provided by: National Park ServiceCrossref Funder Registry ID: http://dx.doi.org/10.13039/100007516Award Number: Funding provided by: U.S. Geological SurveyCrossref Funder Registry ID: http://dx.doi.org/10.13039/100000203Award Number: Funding provided by: Utah State UniversityCrossref Funder Registry ID: http://dx.doi.org/10.13039/100006630Award Number: Funding provided by: Yellowstone Forever*Crossref Funder Registry ID: Award Number: Funding provided by: National Geographic SocietyCrossref Funder Registry ID: http://dx.doi.org/10.13039/100006363Award Number: Funding provided by: Natural Sciences and Engineering Research Council of CanadaCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100000038Award Number: Funding provided by: Alberta Conservation AssociationCrossref Funder Registry ID: http://dx.doi.org/10.13039/100007583Award Number: Funding provided by: Camp Fire Conservation FundCrossref Funder Registry ID: http://dx.doi.org/10.13039/100020095Award Number: Funding provided by: National Science FoundationCrossref Funder Registry ID: http://dx.doi.org/10.13039/100000001Award Number: DEB-1245373Funding provided by: National Science FoundationCrossref Funder Registry ID: http://dx.doi.org/10.13039/100000001Award Number: 2017208739Please refer to the corresponding publication for methods of elk telemetry, determination of cause of mortality, elk age structure, and recovery of wolf-killed elk. Elk telemetry and survival data were processed into the format required by R package Flexsurv for competing risk analysis. Elk have records for each 'elk year' they were observed during the study period (2000–2009, 2011–2016), where 'elk year' runs from June to May. Start and stop times refer to their ages at the beginning and end of each year. The start age is mid-year if they were captured and marked that year, the stop age is at the end of the year unless they died, their collar failed, or they went missing. For elk marked as yearlings, we excluded their yearling year of data. Elk telemetry and survival data were processed into the format required by R package Wild1 for CIF analysis. These elk are the same as those in the other dataset, but the format was changed. Here time refers to days of the year rather than elk age. Please see the README file for additional information