Notes on seabirds 78. Deposition rates of carcasses on the beach in the Netherlands
Atlantic seabirds , Volume 6 - Issue 2 p. 79- 80
Few accurate estimates exist of deposition rates of carcasses on beaches. Scavengers remove corpses and many carcasses become buried in sand or wash back into the sea, as a result of which normal beached bird surveys have a tendency to underestimate the numbers of birds washing ashore. To eliminate such factors as good as possible, a very intense survey programme is required, including daily visits to the shore. In The Netherlands, an 8 km stretch of coastline (six km of dike and two km of sandy beach) has been visited nearly daily since March 1988 by a dedicated team of observers. In contrast to most other beached bird surveys, corpses found here are typically recorded as ‘fresh’ and most washed ashore the night before the survey. We may assume that very few corpses have been missed, certainly so on the dike, where persistence rates are extremely high (Camphuysen 1989), and where diurnal scavengers (mainly crows and gulls, increasing numbers of Red Foxes Vulpes vulpes in recent years) often arrived only after the observers. The uninterrupted series of 195 months of data showed a substantial variability in deposition rates between months, but normally with a peak between November and March (Fig. 1), with a maximum of 4.6 ± 3.9 corpses per day (0.57 ±0.49 per km per day) in February. Between years, the number of corpses washing ashore averaged 553.5 ± 196.0 (69.2 ± 24.5 per km). Extrapolating these figures to the entire Dutch North Sea coast line would result in an estimate of nearly 27,000 ± 9500 corpses washing ashore per annum.
|546235.jpg Cover Image , 9kb|