Swiss vineyards provide habitat for threatened woodlarks

Vineyards seem to be a hot topic in the field of ecology right now. Several recent reports indicate that they can provide good homes for several species of bird, some of whom earn their keep by eating pest species that damage grape crops. Now, collaborators from the University of Bern, the Swiss Ornithological Institute, the University of Lausanne, and the University of Cape Town have produced results indicating that vineyards in the Valais region of Switzerland may be able to provide both feeding and breeding habitat for the woodlark (Lullula arborea)--a vulnerable species of songbird whose numbers have been on the decline since the 1950's.

(Woodlark, Lullula arborea)

Not all vineyards are up to the task, however. This was revealed by a study of the microhabitats utilized by woodlarks within the larger vineyard landscape. To collect data for the analysis, researchers attached radiotracking devices to 7 woodlarks (5 males and 2 females) in order to see where they spent the bulk of their time. Ecological characteristics of woodlark haunts were then compared to those of nearby areas that the birds avoided.

Focal birds were tracked over a period of 88 days, during which time the animals were recorded using a total of 684 patches of vineyard. Homerange size per woodlark varied dramatically. While some birds covered only about 1 hectare, others used areas more than 10 times this size; the average territory was 5.2 hectares. The habitat characteristics that appeared to have the greatest influence on woodlark presence were vineyard type and age, herbicide application regime, ground vegetation cover, vegetation height, and the presence of anthropogenic structures such as walls and roads.

(Vineyards in Valais, Switzerland)

Specifically, woodlarks were less likely to utilize older vineyards--probably because these had more densely planted vines and were treated with higher levels of herbicide. However, the birds seemed to prefer areas planted in a more traditional style, where plants branched low above the ground and rows were planted slightly closer together. Areas with high levels of herbicide application were avoided; woodlarks were fond of areas where short vegetation was allowed to cover 45-60% of the ground. On the other hand, the birds appeared to avoid human-installed infrastructure.

Overall, the woodlarks' occurrence patterns indicate that the birds prefer a mosaic style habitat--one that offers grassy patches where they can breed, but areas of bare ground where they can forage for invertebrate prey. Older techniques of vineyard management tend to emphasize use of herbicides in order to keep a highly mineralized--or bare--ground beneath the vines. Newer, more environmentally-friendly methods (sometimes referred to as "integrated production policies") avoid adding as many chemicals--good news to the 125-150 pairs of woodlarks (half of Switzerland's total population) that live in Valais.

(Woodlark-friendly vineyard habitat, where the ground is covered by a mix of short grass and bare patches)

Unfortunately, only about 5% of Valais' vineyards currently use these new cultivation techniques. The researchers strongly suggest that more Swiss wine growers should strive to make their product in a bird-friendly way--something that can easily be achieved by treating only every second row of vines with herbicides. This simple tactic could help bring an at-risk species back from the brink--and probably win over the hearts and minds of more than a few potential wine buyers.

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Arlettaz, R., Maurer, M.L., Mosimann-Kampe, Nusslé, S., Abadi, F., Braunisch, V., and Schaub, M. 2012. New vineyard cultivationpractices create patchy ground vegetation, favouring woodlarks. Journal of Ornithology 153:229-238.

Thanks to the following websites for providing the images used in this post:
http://www.birdforum.net/opus/Wood_Lark
http://fineswisswine.com/the-vineyards.php
http://www.vogelwarte.ch/recovery-programme-for-the-woodlark.html