Regional demography of Icelandic rock ptarmigan and its implications for harvest management

The rock ptarmigan is a popular game bird in Iceland, but management of hunting has tended to be controversial.  We were interested in whether regional differences in ptarmigan demography exist and, if so, their implications for harvest management.
We fit integrated population models (IPMs) to monitoring data from six hunting regions of Iceland during 2005 – 2023, and then examined equilibrium and non-equilibrium harvests strategies based on an objective to maximize sustainable harvest.
Survival and reproductive rates tended to be similar among regions, except in the demographically important Northeast, where survival was lower and productivity was higher.  There was a negative relationship between post-breeding age ratio and spring abundance in all regions, although the strength of density dependence varied.  Spring abundance was stable in all regions, although harvest rates tended to decline, and adult survival rates tended to increase.  There was a tendency for temporal patterns of d..., We relied on ptarmigan monitoring data collected and compiled by the Icelandic Institute of Natural History and made publicly available (https://www.ni.is/en/research/monitoring-and-research/voktun-rjupnastofnsins).   We partitioned data into six regions used for setting hunting seasons in Iceland: E – East, NE – Northeast, NW – Northwest, S – South, W – West, and WF - Westfjords (Fig. 1).  For each region, we compiled transect-based estimates of spring abundance, hunting-season age ratios, spring age ratios (where and when available), total harvests, and the number of days afield by hunters.  For each region, we used the same basic structure for population dynamics of the spring breeding population, expressing change in population size as a function of seasonal survival of juveniles and adults, post-breeding age ratio, and harvest rate. To estimate model parameters, we used Markov Chain Monte Carlo simulation, using JAGS 4.3.0 run in the R computing language with the package jagsUI., , # Regional demography of Icelandic rock ptarmigan and its implications for harvest management

[https://doi.org/10.5061/dryad.c59zw3rg3](https://doi.org/10.5061/dryad.c59zw3rg3)

Data from six hunting regions in Iceland that were used to fit integrated population models for rock ptarmigan.

## Description of the data and file structure

Data are stored as [RDS (R Data Serialization) files. An RDS file is a binary serialization format in R that allows you to save R objects to a file while preserving their class, attributes, and structure. ](https://www.geeksforgeeks.org/data-serialization-rds-using-r/)They can be read with the readRDS() command in R. There is one file for each hunting region. The files contain a single R list, with the following variables: nyears - number of years beginning in 2005 (except 2006 in the West region); pop - spring abundance in thousands; H - harvest in thousands; F - the number of birds aged in the fall; yf - number of those that were juveniles; S - numbe...