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Archived Postings

June 11, 2007 – June 17, 2007

The ability to reproduce is essential for the survival of any species. Migrant songbirds fly to the boreal forest from Mexico, Central America, or even as far away as South America just to raise young in order to perpetuate their species. The energetic demands on the songbirds during both migration and breeding are huge, so the parents will do as much as possible to ensure that the energy is not wasted and they have a successful brood. The most basic step for any bird to raise offspring is to have a safe and secure nest. Many of the songbirds are too small to be able to physically defend their nest from predators, so their nests are well camouflaged and well hidden. During an afternoon hike in the forest, many people will walk right past a nest without realizing that it is there. Like other songbirds, Canada warblers are also very good at hiding their nests and seem to excel at keeping them hidden from researchers. Finding one can take days. Nest searching is a critical part of the LSLBO’s Canada warbler project. Our nest monitoring goals to is to collect data on nestling growth development and to document general nesting behaviour. So far, after a week of searching, only one Canada warbler nest has been found. Part of the difficulty in locating a Canada warbler nest is because of their preferred nesting habitat. Canada warblers are ground nesters. Their nests are built in hollows found either at the base of a shrub, at the base of a tree stump, or under a fallen log. The habitat which they prefer to nest in is thick with undergrowth. The thick undergrowth limits the ability to visually track the male or female, which is key to finding the nest. It becomes frustrating when you lose sight the female you’ve been tracking behind a bunch of shrubs and have to wait another hour until she comes up from the nest to feed again. Parental behaviour is a major factor in nest searching since they are the ones that are going to lead you to that nest. Parental behavior changes depending on the stage of the nesting. During nest building the female is busy collecting nesting material, but she hard to track because she’s constantly moving around and relatively silent. During incubation, the female will sit on the eggs for a variable amount of time depending on the temperature and the weather. She will periodically leave the nest for a few minutes to feed, making a few soft chips while she is out. When the young have hatched, the female will remains incubating, but will leave more often to collect food for the nestlings. The males, however, are of little help in locating a nest. They roam around their territory, singing away. It seems they are taunting you, saying “I have a nest nearby, you can’t find it”. At times he will briefly interact with the female. After the young have hatched, he is more actively involved in the nest by frequently bringing food to the very hungry nestlings. If you happen to get to close to a nest, the parents will madly chip at you in attempts to distract you and try to lead you away from the nest. At this point, you know your close, it is a now a matter of time. Unfortunately, you have to back off otherwise they will not return to the nest. Searching for nests is a challenging aspect of our summer work. It takes a lot of patience and hours of observations. For anyone who thinks this is an easy task, I have a challenge for you. Just throw your house keys into the forest and go looking for them. You can put a little device on them that will beep every hour or so, just to give you a chance. We don’t want you to be locked out of your house for day.

2010