Title
Estimating arthropod survival probability from field counts: a case study with monarch butterflies
Campus Units
Entomology, Natural Resource Ecology and Management, Statistics
Document Type
Article
Publication Version
Published Version
Publication Date
2020
Journal or Book Title
Ecosphere
Volume
11
Issue
4
First Page
e03082
DOI
10.1002/ecs2.3082
Abstract
Survival probability is fundamental for understanding population dynamics. Methods for estimating survival probability from field data typically require marking individuals, but marking methods are not possible for arthropod species that molt their exoskeleton between life stages. We developed a novel Bayesian state‐space model to estimate arthropod larval survival probability from stage‐structured count data. We performed simulation studies to evaluate estimation bias due to detection probability, individual variation in stage duration, and study design (sampling frequency and sample size). Estimation of cumulative survival probability from oviposition to pupation was robust to potential sources of bias. Our simulations also provide guidance for designing field studies with minimal bias. We applied the model to the monarch butterfly (Danaus plexippus), a declining species in North America for which conservation programs are being implemented. We estimated cumulative survival from egg to pupation from monarch counts conducted at 18 field sites in three landcover types in Iowa, USA, and Ontario, Canada: road right‐of‐ways, natural habitats (gardens and restored meadows), and agricultural field borders. Mean predicted survival probability across all landcover types was 0.014 (95% CI: 0.004–0.024), four times lower than previously published estimates using an ad hoc estimator. Estimated survival probability ranged from 0.002 (95% CI: 7.0E−7 to 0.034) to 0.058 (95% CI: 0.013–0.113) at individual sites. Among landcover types, agricultural field borders in Ontario had the highest estimated survival probability (0.025 with 95% CI: 0.008–0.043) and natural areas had the lowest estimated survival probability (0.008 with 95% CI: 0.009–0.024). Monarch production was estimated as adults produced per milkweed stem by multiplying survival probabilities by eggs per milkweed at these sites. Monarch production ranged from 1.0 (standard deviation [SD] = 0.68) adult in Ontario natural areas in 2016 to 29.0 (SD = 10.42) adults in Ontario agricultural borders in 2015 per 6809 milkweed stems. Survival estimates are critical to monarch population modeling and habitat restoration efforts. Our model is a significant advance in estimating survival probability for monarch butterflies and can be readily adapted to other arthropod species with stage‐structured life histories.
Rights
Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.
Language
en
File Format
application/pdf
Recommended Citation
Grant, Tyler J.; Flockhart, D. T. Tyler; Blader, Teresa R.; Hellmich, Richard L.; Pitman, Grace M.; Tyner, Sam; Norris, D. Ryan; and Bradbury, Steven P., "Estimating arthropod survival probability from field counts: a case study with monarch butterflies" (2020). Entomology Publications. 572.
https://lib.dr.iastate.edu/ent_pubs/572
Included in
Entomology Commons, Natural Resources and Conservation Commons, Natural Resources Management and Policy Commons, Statistical Models Commons, Survival Analysis Commons
Comments
This article is published as Grant, Tyler J., DT Tyler Flockhart, Teresa R. Blader, Richard L. Hellmich, Grace M. Pitman, Sam Tyner, D. Ryan Norris, and Steven P. Bradbury. "Estimating arthropod survival probability from field counts: a case study with monarch butterflies." Ecosphere 11, no. 4 (2020): e03082. doi: 10.1002/ecs2.3082.