Monitoring van de Huiszwaluw Delichon urbica in 1993 in Nederland
Het Vogeljaar , Volume 42 - Issue 4 p. 159- 161
In 1993 1531 quarters of 5 km grids were investigated on the presence of nests of the House Martin (Delichon urbica). For this year a number between 125.000 and 132.000 nests is calculated. In comparison with the 1992 count this is a light increase, but in comparison with the 1965 count it is a sharp decrease of at least 60%.
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