|Institution:||University of Iceland|
|Keywords:||Umhverfis- og auðlindafræði; Líffræði; Stofnstærð (vistfræði); Rjúpa; Líffærafræði|
|Full text PDF:||http://hdl.handle.net/1946/17257|
The rock ptarmigan (Lagopus muta) is the main game-bird in Iceland and has a population that varies cyclically, usually peaking every 10 years. Given these population cycles and its cultural importance, the rock ptarmigan is studied throughout the year. Ptarmigan hunting is closely monitored and commerce of ptarmigans and their related products is forbidden since 2005 to assure sustainable harvest. The ptarmigan health project, which started in 2006, has focused on the general condition of the ptarmigans and how different health parameters relate to population changes during a population cycle. One of the parameters the project is studying is the preen gland. This gland is a holocrine organ exclusive to birds that produces preen oil, a secretion that birds spread through their plumage during preening. The preen oil has been proposed to offer protection against growth of feather degrading bacteria and fungi, as well as fighting ectoparasites. The present study aims to increase the understanding of the functions of the preen gland, specifically the changes in mass of the preen gland in rock ptarmigans in relation to sex, age, year and parasite burden, using data from ptarmigans collected in North-East Iceland from 2007-2012. The mean preen gland mass was significantly higher in males than in females, as well as in adult birds than in juvenile birds, but the effects of sex and age were no longer significant once corrected for body size. The year of collection had the greatest effect on the mass of the preen gland. Moreover, it was observed that the preen gland mass showed a significant negative relationship with ectoparasite richness and ectoparasite burden, as well as with the presence of chewing lice. This study provides evidence that the gland is a part of the ptarmigan outer defenses against ectoparasites.