Dynamic N-occupancy models: Estimating demographic rates and local abundance from detection-nondetection data

Sam Rossman, Charles B. Yackulic, Sarah P. Saunders, Janice Reid, Ray Davis, Elise F. Zipkin

Research output: Contribution to journalArticlepeer-review

38 Scopus citations


Occupancy modeling is a widely used analytical technique for assessing species distributions and range dynamics. However, occupancy analyses frequently ignore variation in abundance of occupied sites, even though site abundances affect many of the parameters being estimated (e.g., extinction, colonization, detection probability). We introduce a new model ("dynamic N-occupancy") capable of providing accurate estimates of local abundance, population gains (reproduction/immigration), and apparent survival probabilities while accounting for imperfect detection using only detection/nondetection data. Our model utilizes heterogeneity in detection based on variations in site abundances to estimate latent demographic rates via a dynamic N-mixture modeling framework. We validate our model using simulations across a wide range of values and examine the data requirements, including the number of years and survey sites needed, for unbiased and precise estimation of parameters. We apply our model to estimate spatiotemporal heterogeneity in abundances of barred owls (Strix varia) within a recently invaded region in Oregon (USA). Estimates of apparent survival and population gains are consistent with those from a nearby radio-tracking study and elucidate how barred owl abundances have increased dramatically over time. The dynamic N-occupancy model greatly improves inferences on individual-level population processes from occupancy data by explicitly modeling the latent population structure.

Original languageEnglish (US)
Pages (from-to)3300-3307
Number of pages8
Issue number12
StatePublished - Dec 1 2016

Bibliographical note

Funding Information:
The work in this manuscript grew out of discussions from a working group supported by the John Wesley Powell Center for Analysis and Synthesis, funded by the USGS.

Publisher Copyright:
© 2016 by the Ecological Society of America.


  • Barred owl
  • Demographic rates
  • Dynamic
  • Heterogeneity
  • Latent
  • N-mixture model
  • Occupancy
  • Species distribution models


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