2022 Early Hearing Detection & Intervention Virtual Conference
March 13 - 15, 2022
9/28/2018 | 8:35 AM - 8:50 AM | Body Condition and Population Change of Rock Ptarmigan | Eccles Conference Center Auditorium
Body Condition and Population Change of Rock Ptarmigan
The rock ptarmigan (Lagopus muta) in Iceland undergoes regular changes of numbers. Since 2003 there have been three peaks of numbers in North-east Iceland. The first peak was in 2005, the second in 2010 and the third in 2015. The general health of this ptarmigan population was studied in early October 2006-2017. Variables measured included morphology, body reserves, food and parasite infections. The annual sample was 100 birds, 60 juveniles (sex ratio m:f 50:50) and 40 adults (sex ratio m:f 59:41). It was known that mortality during November?March determines population change. The collection time (first week of October) was selected to evaluate the health of the birds at the start of this critical period. The body condition index (BCI) of the ptarmigan was significantly related to sex (females scored higher than males), age (adults scored higher than juveniles) and year. The year effect indicated a relationship between the BCI and such demographic factors as density, mortality and the rate of population change (r = ln(Nt/Nt-1)). Density lagged the BCI by 1 or 2 years but r and mortality changed more or less in synchrony with the BCI, the relationship with r was positive but negative with the mortality rate. These results suggest that condition or health as such is an important element of population change of the ptarmigan in Iceland, and further that the condition of the birds is determined during summer and early autumn (June through September). These results will be discussed in relation to predation, parasitism and food.
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Presenters/Authors
Ólafur K Nielsen
(), Icelandic Institute of Natural History, okn@ni.is;
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