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Archived Postings

May 13, 2007 – May 20, 2007

When the LSLBO was established in 1994, its primary commitment was to monitor populations of migratory songbirds. Today, in its fourteen year, that commitment still holds. But the organization has now grown and evolved to a point where it can start working on projects outside the boundaries of the banding station. We had the opportunity to do such a project early this spring. Before the songbird migration began the LSLBO conducted owl surveys within the Slave Lake Forest Management Area. Owls are one of the groups included in the biological diversity monitoring strategy of the forestry companies operating in the area. Eight species of owls regularly breed in the area, some are more commonly found than others, and their reliance on a prey base and their dependence on specific nesting, hunting, and roosting habitats make them excellent biological indicators. This means that negative habitat changes can be detected if significant declines in owl populations are observed. The tricky part about owls is that their populations are cyclic and can show dramatic variation from year to year. It is important to be able to identify natural population fluctuations against possible anthropogenic causes. This is why the owl monitoring surveys are part of a long term monitoring plan which began in 1999. 2007 marks the fourth year that the owl monitoring surveys have been conducted within the forest management area. Owls are secretive, they have large ranges, and many species are nocturnal. So how do you go about finding owls that are widespread across the landscape in the middle of the night? The answer is to get them vocalizing. At each calling station a series of owl breeding calls is broadcasted through a radio. A nearby owl thinks this auditory lure is another male invading its territory and will respond with its own call, effectively saying “hey buddy, you’re in my territory, get lost and go find your own”. It works quite well. But it is all listening for the owls to call back; very rarely does the surveyor actually see one. The most important part of these surveys is timing. Surveys have to be completed before nesting begins, which is typically at the end of April, otherwise the owls will not respond as frequently and you do not want to distract the owls from their important nesting duties. The most challenging part of the surveys is the time of year; it coincides with the spring thaw. This means negotiating muddy roads at night. Inevitably there comes a point when quading knee deep in mud at three in the morning to hear owls call seems a little ridiculous. Then you come to a stop on a ridge. The sky is filled with stars and you cannot recognize a single constellation. Northern lights are dancing in the sky giving a green and pink light show. Suddenly, pair of barred owls begins their unmistakable duet. Sometimes, if you’re lucky, a wolf will begin to howl. Scenes like that do occur and which just adds to the intrinsic value of this important work. Plus you’re working with owls, and owls are great. Now that I’ve finished reminiscing about the owl work, it is time to focus again on migration monitoring. We still have not seen any sort of major passage of migrants, but they are trickling in. Daily banding totals are averaging about 25 birds a day. A host of new species have arrived since last week. We have seen the first yellow warblers, ovenbirds, northern waterthrush, Baltimore orioles, chipping sparrows, clay-coloured sparrows, rose-breasted grosbeaks, and western tanagers. This is a fun time of year because you just never know which species will show up on the next net check.

2010