GROEN NM, FRIESWIJK JJ & BOUWMEESTE, J (1995) Why do Common Terns Sterna hirundo breed on roofs?. LIMOSA 68 (2): 65-71.

Common Tern Sterna hirundo Common Terns have nested on the extensive (40 ha) flat roofs of the Flower Auction complex in Aalsmeer (VBA), Netherlands, since the late 1980s. In June, 1990, the pebble cover of these roofs was removed. In an attempt to supply Common Terns with nesting habitat on the roofs thereafter, eight large 'boxes' (2.5 X 2.5 m, 9 cm deep) filled with fine gravel were placed in a cluster on the roof. Although this reduced the size of potential Common Tern nesting habitat from the original 400 000 to 50 m2 post-1990, the operation was successful: about 50 pairs nested in 1991, 120-130 in 1994 (tab. 1). Six visits were made to this colony in 1994 between 28 May and 5 August, in order to gather information on breeding success and chick growth. To reduce disturbance, visits were brief. Consequently, data collected did not allow for application of the Mayfield-method; breeding success, hatching success and fledging success were determined according to Veen (1977). Growth rate of chicks was determined by measuring mass and total head length. For comparative purposes, similar data were collected in another colony of Common Terns newly established near Amsterdam (polder 'IJdoorn' adjacent to Lake IJsselmeer), where birds nest on the ground. The artificial nesting habitat of gravel-filled boxes resulted in very high nest density: 2.38 nests/m' (up to 19 nests per box). Mean clutch size (2.46), hatching success (c. 67%), breeding success (c. 34%) and mean number of young raised per pair (c. 0.83) were all relatively low in the roofnesting population. Overall, growth curves of chicks at VBA and in IJdoorn were very similar, but in the phase between 40 and 100 g, chicks at VBA grew faster. This is interpreted as a result of a larger proportion of single chick-families at VBA. Based on data from recaptures of ringed chicks, mean weight gain of chicks was very similar at the two locations (VBA: 5.78 g/day, IJdoorn: 5.75 g/day; figs. 1-4). Although roofnesting has several advantages over groundnesting (e.g., absence of groundpredators, disturbance and vegetation), it also has several disadvantages:

[free pdf] [dutch summary]