Rapid breeding bird colonisation of Floriade 1982 park Amsterdam

Summary of Dutch article in Vogeljaar 40 (1992) p. 82-85 (John van der Woude).

For the international horticulture exhibition Floriade 1982 in Amsterdam, a park was designed with much natural landscaping: woods, reeds, dunes, etc. and this in a half-open landscape in order to show the flowers on lawns. The park structure was nearly ready by 1980 and as I lived at only 200 m from it I decided to follow the breeding bird colonisation from then on. The park was developed in such a clever way (with many older trees taken from elsewhere and with careful pruning) that the park would seem, in the exhibition year 1982, much older than it actually was. So I was curious if the birds would soon find their way to this 'ripe habitat'.

They did indeed, and especially from 1980 until 1984 the increase in breeding bird numbers was spectacular. Figure 1 shows graphs for eight species, and for these species, the total number of territories rose from 10 to 100 from 1980 to 1984. From 1984 onwards the breeding bird numbers increased much slower, but it's interesting to see how this differed between species: Chiffchaff and Wren kept on increasing in numbers significantly (because of increasing height of the trees, and thickening undergrowth, respectively), while species of the more open habitat of the early stages of the park decreased further (Linnet, White Wagtail).

 
Figure 1. Numbers of breeding bird territories for eight species from 1980 until 1990. From bottom to top: Icterine Warbler, Wren, Dunnock, Great Tit, Garden Warbler, Blackcap, Chiffchaff, Willow Warbler.
 A comparison with the SOVON index numbers for breeding birds across the Netherlands is also interesting (see Figure 2). Indeed, Wren increased much faster than the trend figures in the country show. Greenfinch kept his c. 12 territories throughout the period 1984-1990, despite the decrease of this species across the Netherlands in that period.

 
Figure 2. Numbers of breeding bird territories for four species as percentage of the SOVON index numbers during 1984-1988. From left to right: Wren, Greenfinch, White Wagtail, Icterine Warbler.

Finally, it's interesting to see how fast the birds spread across the park from 1980 to 1990. I computed this for four species (Chiffchaff, Reed Warbler, Blackcap, Wren). Figure 3 shows this for Chiffchaff: a fast spreading, i.e. regularly an establishment on sites relatively far away from the old ones. This rate decreases towards the end of the period because the park filled up with Chiffchaff then. Reed Warbler, in contrast, was much more conservative in this spreading. New territories were close to the older ones, although, seemingly for me at least, enough suitable habitat was present at larger distances from the older territories. Wren shows about the same pattern as Chiffchaff, whereas Blackcap is irregularly spreading from a few strongholds.


Figure 3. For Chiffchaff, numbers of breeding bird territories (curve), and numbers of territories at 0-25 m and 25-50 m distance to territories of the preceding year (bars). Please note that the empty space above the bars indicates new territories at distances larger than 50 m from the preceding year's territories.
 

 
Snapshot from Google Earth 2006 of the Floriade 1982 park in Amsterdam-Zuidoost. This is at the end of metro line Gaasperplas (visible left). The park has been named (and enlarged) Gaasperplaspark after the 1982 exhibition. The scale bar is 200 m.