To monitor levels of pollutants in merlin by analysis of POPs and heavy metals in eggs and feathers. /Feathers and addled eggs of merlin were collected in 1992, 1993, 1994, 1999 and 2000 for chemical analysis of POPs and heavy metals. Comparisons with eggs from museum collections show that there has been a significant shell thinning in eggs of Norwegian merlins. From 1947 up to 1990 the eggs were on average ca. 15% thinner than normal and after 1990 the thinning has been ca. 10%. There are still high concentrations of DDE to reduce reproductive output in some cases. The PCB levels are low compared to the DDE levels and the concentrations of other chlorinated hydrocarbons are also low. Results from mercury analyses indicate possible effects on breeding performance in some adults.
Eggs and feathers
The methods are described in Gabrielsen, G. W., Skaare, J. U., Polder, A. & Bakken, V. 1995. Chlorinated hydrocarbons in glaucous gulls (Larus hyperboreus) in the southern part of Svalbard. - Sci. Total Environ. 160/161: 337-346. Nygård, T. 1999. Long term trends in pollutant levels and shell thickness in eggs of merlin in Norway, in relation to its migration pattern and numbers. - Ecotoxicology 8: 23-31.
Program for terrestrial monitoring in Norway (TOV)