Anleitung zur Brutbestandserfassung von ... - BLMP Online

Weitere Magazine

Empfehlungen

Info

Anleitung zur Brutbestandserfassung von Küstenvögeln im Wattenmeerbereich - 45 - Tab. 4: Methodik der Brutbestandserfassung von Küstenvögeln
Anleitung zur Brutbestandserfassung von Küstenvögeln im Wattenmeerbereich - 46 - Summary Guidelines for censusing typical breeding birds in the Wadden Sea are presented which are based on the German "Guidelines for Censusing Coastal Breeding Birds" (Brunckhorst et al. 1988). The aim of the guidelines is to make the breeding bird data collected in the Dutch- German-Danish Wadden Sea more comparable through the standardisation of methods and the definition of the period during which the various bird species should be censused. Only when the standard methods presented in this paper are followed will it be possible to assess the total population size, distribution and, especially, population trends of the species included in the trilateral "Joint Monitoring Program for Breeding Birds in the Wadden Sea". The census periods for the different species cover 20 to 30 days. Double counts due to movements of breeding pairs during the breeding season (especially Avocet, Blackheaded Gull, Sandwich Tern and Little Tern) can, to a large extent, be ruled out if the methods presented are adhered to. The total census period for breeding bird surveys in the Wadden Sea is from the 10. April to the 10. June (Fig. 4). Within the census areas of the Joint Monitoring Program for Breeding Birds in the Wadden Sea, three counts must be carried out within the census period for each species. In the remaining areas at least two counts should be carried out for each species. The highest number of pairs counted for each species in each site should be used as the value for the number of territorial pairs. Counts of nests should only be carried out once. Colonies of gulls, terns and the Avocet should be counted in the period 3 hours before to 3 hours after high tide. Waders, which breed more or less singly, with, however, the exception of nests which are situated far away from the tidal flats, should be counted in the period 6 hours before to 6 hours after low tide. If possible the counts should be carried out from an elevated position at a distance from the breeding site, for example from the sea dyke. This gives a more static picture and allows for a more overall view than if the site is entered and the birds disturbed. Due to the danger of increased mortality of embryos and young through overheating and exposure, the breeding sites should not be entered during very hot sunny weather and, after hatching, during cold wet weather. Four methods can be used for censusing colonies A-Within large colonies aerial counts or the assessment of aerial photographs of, normally, 0.25 ha census plots which cover about 15% of the colony. B-Ground counts of pairs from a distance in colonies where this is possible. The following categories should be evaluated as one pair: -a brooding bird with its partner in the vicinity, -a brooding bird on its own, -two birds which are sitting, standing or flying together and -a single bird on its own. Small groups of 3 or 4 individuals should be classed as 2 pairs and 5 or 6 individuals as 3 pairs. C-Where the view of the colony is obstructed counts or estimates of all individuals during flights above the colony site after one intentional disturbance and if possible during each visit after one or more natural (bird of prey etc) disturbances. The number of birds which are present in the colony at any one time and the number which are observable or countable is dependent on the species involved and especially on the breeding site. If the number of pairs in such colonies are calculated in an arbitrary and incomprehensible way using various factors, as is the present case in the Wadden Sea, it is not easy to discern population changes. The number of individuals counted should, therefore, be multiplied by a standard factor of 0.7 in order to calculate the number of pairs in such
Seite 2 und 3: Anleitung zur Brutbestandserfassung
Seite 56: Anleitung zur Brutbestandserfassung

Anleitung zur Brutbestandserfassung von ... - BLMP Online

Sie wollen auch ein ePaper? Erhöhen Sie die Reichweite Ihrer Titel.

Template löschen?

Als Template speichern?