Title:

Trends in Namibian Waterbird Populations 2: Grebes and Pelicans

Author(s):
Publication Year:
2010
Abstract:

The following is a summary of waterbird count data for selected species in Namibia, covering the period 1977 to December 2008. For each species the Red Data Book (RDB) status, both global and Namibian, is given, the population trend as per Wetlands International, the number of times the species was counted, the number of times it has passed the 1% population criterion, the maximum count and the sites where it has passed the 1% population criterion. The local trend is calculated using the computer programme TRIM (see an earlier publication for the selection criteria and methods) (Lanioturdus 43-2 - Ed). Population trends are graphically presented as indices relative to a base year (in this case 1991) and thus all have a value of 1 for 1991. Thus an index value of 2 indicates a doubling of the population relative to 1991 and an index of 0.5 would mean half of the 1991 figure. A slope value of 1 would indicate a perfectly stable population, whereas any value above 1 means a positive trend and a value of less than 1 a negative trend.

Publication Title:

Lanioturdus

Volume:
43
Issue:
3
Pages:
8-41
Item Type:
Journal Article
Language:
en

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