A Nest with a View
Abstract from Journal of Avian Biology
15th April 1996
Most birdwatchers feel, instinctively, that small birds choose to conceal their nests as best they can. The densest and most prickly bush is the best place to escape the attentions of the rapacious local cats and Magpies.
However, recent thinking suggests that small birds should not chose the best concealment for their nests because a reasonable view of the surroundings may increase their ability to foil nest predators. A bird unable to see around its nest may move off the nest when a predator is quietly watching, or even be at risk itself if an active predator approaches too close.
Frank Gotmark, Donald Blomqvist, Olof Johansson and Jan Bergvist have now tested this thoroughly on the local Song Thrush population near Gotebug, Sweden. Their results, reported in the Journal of Avian Biology 26: 305-312, are from 271 nests and prove that the birds are not seeking to conceal their nests as much as possible. A good view around is just as important. Artificial nests in more open sites were more likely to be found by the local predators (mainly Jays) but real nests were just as likely to survive in more open sites. Even then, average nest survival was only about two out of every five.
Perhaps the advice given to gardeners to grow dense shrubby areas for nesting birds to be able to survive the attentions of the local Magpies and cats needs to be modified. We should be manufacturing or growing sites which match concealment of the nest with good sight lines from it so that the watchful parents can plan their nest defence.