Written by: Brenda Van Ryswyck, Natural Heritage Ecologist
After the long weekend I was anxious to get up and check the bird nestboxes behind the office. The last check was done on May 16 and the Tree Swallows were just starting to lay eggs. The nestchecks should always be done in the afternoon as the mornings may be chilly and, more importantly, the mornings are when the female birds will be laying eggs, so we do not want to disturb that. As soon as I finished lunch Karlee, the Digital Media Coordinator, and I went out to make the rounds. We started at the west side of the property at ADM1A, this box has been claimed by a pair of Tree Swallows who were the first of the Tree Swallows to start laying eggs. We opened the box to find 6 eggs present, next was ADM1B this is the bluebird nestbox. They had laid 6 eggs (quite a few for a bluebird) and they had hatched last week but I could only confirm 4 last week because there were so many in that little box and piled on top of each other.When we opened it today we easily saw 5 chicks present!
Very good, all look healthy. There may be one more buried under the others or there may be one unhatched egg. The next boxes were just over 100 M away, we designed it this way to maximize the bluebird territories available (more about that next). The next boxes ADM2A and B both look to be Tree Swallow nests but I think only one is active. ADM1B has 5 eggs in it now. Then we wandered to the front of the office where the last nestbox is. Now we have a Tree Swallow nest in this box and today it had its first egg. A few weeks ago this box did have a European House Sparrow nest in it but part of the reason I monitor is to make sure this non-native, invasive species does not use the boxes we have put up. It is better not to have any boxes up than to allow the European House Sparrow to use them. For more information on the destructive nature of the House Sparrow, click here.
While we don’t currently have more than one bluebird pair nesting here we now have to potential to have three. It’s all about the spacing. Previously we had four boxes all up in one corner of the regeneration area. This was inefficient and only allowed one bluebird nest and one swallow nest. Why you ask? Well birds are quite territorial when nesting, especially against their own species. One male Eastern Bluebird will guard a territory for about 90 metres around his nest and chase away any other male bluebirds that try to nest there. Tree Swallows will guard a smaller area about 30 M around their nest. But the bluebird will let the Tree Swallow nest nearby since it is a different species. Last year I posted about giving the nextboxes an upgrade, as part of that I moved a few around so that we had pairs of them farther than 90 m away. I have also “paired” the boxes so an Eastern Bluebird pair can nest in one box beside a box used by a Tree Swallow pair, thus why the boxes are named 1A, 1B and 2A, 2B so on. So we now can have more than one pair of Eastern Bluebirds (and Tree Swallows) nesting here!
And don’t worry, monitoring (checking) boxes like this will not cause the birds to abandon their nest. If done properly monitoring can actually increase the success of these nesting birds. To learn more, check out Birds Canada.
To monitor the Barn Swallow nest I put the mirror onto a pole and carefully slide it over the nest to peer in. One of our two Barn Swallow nests has eggs, the other doesn’t yet have eggs but they should be coming any day! We have an artificial nestcup being used by the one pair of Barn Swallows. This spring (before the swallows had returned) we replaced our doors, one of the nests had been on this door. Because the Barn Swallow is a species at risk and in severe decline, we replaced the habitat they lost (their former nest on our door) with a nestcup on the wall nearby. We were not sure they would accept the nestcup but they did! And now it has two eggs in it! The other pair are on another wall and their nest was not affected by the door replacement. The returning swallows just fixed up their old nest a little and are now re-using it.
We look forward to seeing more chicks hatching in the future!
If you have a bird nesting on your property you can become a NestWatcher! If you don’t, but you have an interest in it maybe contact us about volunteering? We will need one or two dedicated Bluebird Nest Monitors. Contact Brenda Van RysWyck about bluebirds or Liz Wren our volunteer co-ordinator for this or any other volunteer opportunities with CH.