Evaluation of ptarmigan management with a population reconstruction model

Abstract

The rock ptarmigan (Lagopus muta) is a popular game bird in Iceland, but the population has endured a long‐term decline. A hunting ban was enforced in 2003, but 2 years later hunting was allowed again with added restrictions. The aim of this study was to investigate the effects of a change in hunting regulations on the ptarmigan population in northeast Iceland, 1998–2013, using a population reconstruction model and to estimate the abundance of juveniles and adults, natural survival, and harvest mortality. The estimated abundance at the beginning of the hunting season ranged from 42,000 (95% CI = 36,000–49,000) birds in 2002 to 158,000 (95% CI = 105,000–250,000) in 1998. The natural survival of adult rock ptarmigan was density dependent and ranged from 36% to 65% (95% CI = 30–75%). Survival for juveniles was constant and was estimated to be 19% (95% CI = 18–20%). We included a change point in the model to account for a change in the harvest mortality that could have occurred with the changes in the hunting regulations. The results indicated that the change in hunting regulations did reduce ptarmigan harvest mortality and changed the harvest strategies of hunters. Inclusion of a change point in models is useful for managers to test if a change in regulations had an effect on the target population. © 2018 The Wildlife Society.

Host sex and age typically explain variation in parasitism of rock ptarmigan: implications for identifying determinants of exposure and susceptibility

“…However, our samples (~100 ptarmigan per year) represent a small fraction (i.e. 0.07–0.26%) of the overall estimated population within the north–east hunting zone, and are not expected to impact year‐to‐year population size (Sturludottir et al ).…”

Survival and Migration of Rock Ptarmigan in Central Scandinavia

“…Compared to annual survival probabilities for rock ptarmigan in Japan [estimated at 44-74% for birds of different ages: Suzuki et al (2013)], France [61% and 70% in Haut Giffre and Canigou Massif, respectively: Novoa et al (2011)], and Svalbard [40-50% for males and females, respectively: Unander et al (2016)] this is very low survival, bearing in mind that we only estimated survival for a part of the year. At Island, rock ptarmigan survival was shown to be highly variable, varying between 36-65% for adult birds and constant at 19% for juveniles (Sturludottir et al, 2018). Because our study only lasted two years, we are not able to estimate robustly any between year variation due to stochastic environmental factors or variation in harvest pressure.…”

Predator‐prey feedback in a gyrfalcon‐ptarmigan system?

“…Rough estimates of the required predation demonstrate why this question is intrinsically difficult. Around 100 adult predator pairs can be found near peak abundance on the NE Iceland ptarmigan management zone and to these correspond about 100,000 ptarmigan individuals at best (Sturludottir, Nielsen, & Stefansson, ). One might think, given these numbers, that the predators are unlikely to make their prey decline.…”