Wednesday, February 17, 2010

Good news for burrowing owls

this beautiful Burrowing Owl image courtesy of Alan MacKeigan

There has been nothing but bad news about the burrowing owl for a long time in Saskatchewan. According to Nature Saskatchewan's stewardship program, Operation Burrowing Owl (OBO), the province's owl population dropped 92% from 1988 to 2009. I found this stunning statistic in the December 2009 issue of The Blue Jay, Nature Sask's (NS) quarterly journal of natural history.

The rest of the article ("Are Burrowing Owls Using Enhanced Habitat"), written by OBO's Andrea Kotylak and Margaret Skeel, has some news that may be cause for cautious optimism. Starting in the year 2000, OBO began working with landowners in priority regions who had burrowing owls recently but lost them. The project aimed at enhancing habitat by providing funding assistance to have landowners seed cultivated land to non-invasive tame species of perennial grass. The idea was to try to attract burrowing owls to nest there or in existing adjacent grassland. In the first six years they sponsored 85 projects converting a total of nearly 12,000 acres to perennial grass.

In the summer of 2007, NS sent four staff people out into the field to see what birds were using the habitat. Their method was to look at 28 quarter sections of grassland: 10 were project sites and 18 were adjacent quarters. They found a "total of five pairs (all nests fledged young) and 11 single Burrowing Owls on six of the 28quarter sections that comprised the study." (Blue Jay, 67 (4), December, 2009, p. 233) Best of all, they found owls nesting on three of the ten quarter sections that were part of project sites (two pairs nested in native grass portions of the quarters). A 33% rate is pretty darn good, proving that this kind of habitat enhancement attracts nesting owls. Whether it can hold onto them year over year is another matter, but this is a promising start. Interestingly, it seems that the sites only began to attract owls after the reseeded land had matured at least seven years.

As well, they recorded other grassland birds using the ten project sites: western meadowlark (on eight sites), savannah sparrow (seven, horned lark (five), Baird's sparrow (four), vesper sparrow (three), bobolink (three), clay-coloured sparrow (two) and Sprague's pipit (two). It would take a different kind of study to determine if the habitat actually fosters a healthy population of these species and is not merely an ecological trap that encourages birds to attempt nesting only to fail. However, these results from a simple program that reseeds land to non-native but non-invasive grass show that it is an approach worth more study.

Native grass is better, but remains expensive and difficult to get established. Prairie conservationists have sometimes been unwilling to consider non-native plantings as a valid tool in their arsenal, but it may be a strategy that could be used in certain situations, as this study by OBO staff implies.

After the study, in 2008 and 2009, even more pairs and single owls were reported at several project sites, lending more encouragement to the OBO team.

For more details on OBO and Nature Sask's other "Stewards of Saskatchewan" (SOS) programs protecting habitat for endangered species, take a look at this page on Eco-Index.

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