Ardea Official journal of the Netherlands Ornithologists' Union |
Piersma T., Rogers K.G., Boyd H., Bunskoeke E.J. & Jukema J. (2005) Demography of Eurasian Golden Plovers Pluvialis apricaria staging in The Netherlands, 1949–2000. ARDEA 93 (1): 49-64 |
Changes in annual survival and recruitment rates over the second half of the 20th century were calculated from 1834 recoveries and 400 recaptures in the years following ringing of 77 069 Eurasian Golden Plovers ringed in The Netherlands. Almost all plovers were captured by the traditional ‘wilsternetting’ technique. From 1980 most of the birds were aged, and the number of birds ringed stabilised at 2500–3500 birds per non-breeding season. The birds breed in Fennoscandia and northwest Russia. The Netherlands provided 18% of all recoveries and France, Spain, Denmark and Portugal together a further 64%; all these countries showed a decline in recovery rate over the last two decades. Using program MARK, vital rates in Eurasian Golden Plovers were examined. A Burnham model that combines data from both live recaptures and dead recoveries for the period 1980–1997 showed that juvenile true survival rates were 13.6% lower than adult survival rates. A recaptures-only model for data on live encounters from 1949–2000 suggests that apparent annual survival (Phi) was 25% lower before 1963 than later (0.552 and 0.735 respectively) and that the recapture probability (p) doubled after 1976. The estimated average true adult survival rate (S) in the Burnham model was 11% higher than apparent annual survival in the recaptures-only model (0.825 vs. 0.735), a difference explained by emigration. There was some evidence for increasing numbers of adults to move further southwards in colder winters, but survival was only reduced in the coldest winters. Pradel (or temporal symmetry) models were used to estimate annual growth rates of the population. The Eurasian Golden Plover population staging in The Netherlands appeared to show consistent growth from 1963/64 and by 1990/91 had reached a level ca. 4.5 times the initial size. Since the early 1990s population size may have levelled off, possibly as a result of density-dependent effects. |