WYMENGA E (1997) Early roosting Black-tailed Godwits Limosa limosa in summer 1993 as an indication for a bad breeding. LIMOSA 70 (2): 71-75.

In spring and summer, before and after the breeding season, Black-tailed Godwits Limosa limosa spend the night on communal roosts. In the province of Friesland in early spring many roosts are found on inundated pastures and in fresh water marshes. After fledging of the young, in June and July, the Godwits concentrate on a few major roosts, because many of the roosting sites which are used in spring, have dried up by then. In most years the first Godwits arrive in March on one of the major roosts, the Jan Dirkspolder near Earnew1lld (Eernewoude). In spring the numbers peak in the first half of April, while by the end of that month nearly all Godwits spend the night in their breeding territories. In May Godwits are almost absent from the roost. In the course of June the number of roosting birds increases and peak numbers are reached around mid-July.
      The numbers of Godwits at the roost in 1993 developed differently. As early as Maya few hundred birds were present, whereas in the first week of June 2.000 individuals were counted (Fig. 1). In July 1993 a maximum of only a few hundred Godwits were present. These events were probably related to (very) low breeding succes in the vicinity. The Godwits at the roost in May and the first week of June were present at a time when normally the adults are breeding or tending young. Almost no juveniles were seen at the roost in 1993 (1-2 % by the end of July), while in the other years by the end of July the percentage of juveniles had increased to 90-95 % (probably because of early migrating adults). This strongly suggests that the birds present in May and early June 1993 had lost their eggs and/or young. As a result of high temperatures in April 1993, almost all grassland parcels in the area were mawn within a very short period between late April and the first week of May. This led to heavy losses of clutches and young. Since Black-tailed Godwits rarely replace clutches after 10 May, breeding success was probably extremely poor in the area. During several visits to the surrounding breeding areas in the first half of May 1993, almost no pairs of Black-tailed Godwits with young were seen, in contrast to other years.
      As a result of more efficient mowing equipment nowadays farmers are less dependent on long periods of good weather in spring to cut and dry the grass. Consequently mowing takes place both earlier and over larger areas simultaneously, resulting in great risks for breeding Godwits (and other meadow birds). Therefore it is very important that at least in part of the breeding area grasslands parcels are mawn later in the season. 'Safe areas' like this should not only be present in special nature reserves but also in private agricultural grasslands, most of which are used intensively. These comprise the largest area in The Netherlands and hold by far the largest part of the Dutch breeding population of Black-tailed Godwits. Currently, experimental projects are initiated to establish such safe areas outside the specially protected nature reserves.

[free pdf] [dutch summary]