Inventarisatie van de Huiszwaluw Delichon urbica in 1992 in Nederland

In 1992 1486 quarters of 5 km grids were investigated on the presence of nests of the House Martin (Delichon urbica). An average of 24.6 nests was found in each quarter. Since there was an underestimating of the nests of about 10% and the area covered about 25% of the quarters of 5 km grids in which House Martins are nesting a total of 154.550 nests are calculated. In comparison with the 1991 counts this is an increase of 4.5%. Quarters with more than fifty nests were situated in watery areas. Results of the use of and positive experiences with artificial nests, help for young House Martins which had fallen out off their nests, and measures to protect the species against the deliberate removal of their nests are described.