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| tree swallow nesting in a box |
Ecologists talk about limiting factors. These are the things that will potentially limit the size of a population. many will know that tree swallows belong to a group of birds known as aerial insectivores. Aerial insectivores as the name suggests, eat insects while they are flying. This group of birds is in perilous trouble and are experiencing dramatic declines. In northern Ontario the population dropped by over 30 percent between 1985 and 2005. This was recorded in the results of 2 Ontario breeding bird atlas projects. The next breeding bird atlas is slated to begin in 2021 and takes 5 year of intensive field work by thousands of volunteers and trained ornithologists, I fear the news following this study will be even gloomier. Back in my teaching life I was telling a group of students about this decline and a 16 year old guitar playing youth in my class named Zak took it upon himself with plans for bird house construction, and a father who was in the construction business. Zak organized the class and we were able to get some funding and before we knew it we had over 70 boxes around the marsh and we bumped up the number of boxes along highway 569 to over 80.
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| first nesting eastern bluebirds at kerns public photo by Joanne Goddard |
Zak understood the lesson in ecology about limiting factors. It has always bewildered me that bluebirds and tree swallows have to nest in a cavity but they cannot make the cavity themselves. They have to depend on finding abandoned woodpecker holes or discovering a cavity perhaps created by a branch ripping a hole in a tree in a wind storm. Zak, however, knew that if we could increase the number of cavities by putting up lots of birdhouses we could help out the swallow population. By eliminating the limiting factor in our area we could help the swallow population rebound.
I am not sure if Zak has ever taken the time to do a little marsh math but here I go. Let's keep it simple let's say Zak and his classmates put up 100 boxes and lets say 50 percent of the boxes are used. Let's also say the average clutch is 4 eggs. Zak is responsible for 200 young birds a year. It has almost been ten year since Zak got his classmates to put up those boxes so he is responsible for over 2000 birds being fledged not to mention how may of their progeny have gone on to have successful clutches of their own. The lesson learned here is that cavities are a very good thing!!
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| photo taken by Bob Fotheringham at Ruthven Park banding site |
When we first were putting up boxes my recollection was that we would be upset when a tree swallow took a potential box from a bluebird but now we have seen the drop in occupancy rate of our boxes and are delighted to see a swallow make a home in any box . Occupancy has dropped from around 75-80% success to closer to 50%. Some of the declines could be due to the sheer number of boxes we now have up. As I mentioned we originally had very few boxes around the marsh itself, preferring to establish a "trail" along highway 569. This was done for pragmatic reasons. It is easy to check on boxes by driving from box to box and we could not afford the hardware or poles to put the boxes up and took advantage of fence posts. With a little bit of funding we were able to put many of the boxes up on t-bars and donated pipe around the marsh. Once the boxes went up around the marsh the occupancy rate went down along the highway suggesting perhaps that the best boxes would be closest to where the adults could feed. We have since expanded our swallow box program to include all of the sewage lagoons, we have boxes in Englehart, Earlton, Newliskeard and in the old and new lagoons in North Cobalt
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| nest lined with feathers indicates a tree swallow nest |
Another limiting factor for tree swallows is finding feathers to line their nests. We used to see swallows fighting one another to get feathers to their nests. We have eliminated that by putting out duck feathers donated by hunters so each spring we can spread feathers around the marsh to help eliminate another limiting factor. Again because feathers are easier to find at the marsh we would expect to see a higher occupancy rate where it is easiest to find food and feathers.
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| Ron Judd removing a nest |
This was all a very long winded explanation of why we were out this weekend cleaning out boxes. We had 15 volunteers that came out to help us clean the boxes. Two weekends ago Curtis and Clayton Quinton cleaned all of the boxes at the marsh on snowmobiles which was a marsh first. That left volunteers the boxes on hwy 569 and the sewage lagoons.
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| happy volunteers |
Every year it is such a thrill for me emptying the boxes to see if they were used and if they were used by a tree swallow or a bluebird and knowing that we are able to do something very simple to help out these populations. If boxes are not cleaned out the females will build a nest on top of the previous years and in 3 years the boxes will no longer be usable, so it is essential to clean them out. So thanks to all of the volunteers who came and helped out. I really appreciate and it would seem that increasingly the the birds are going to depend on our efforts to provide cavities even more . If you would like to help our nest box program please check the marsh website www.thehilliardtonmarsh.com to see how you can donate to our nest box program so we can continue to keep up our fight to promote cavities!!! My dentist friend Rick Caldwell won't like that but then again he helped me put up some of the first boxes in the area. The past president of the Ontario Dental Association promoting cavities...... only for the love of the birds!!!!
should you wish to build your own box here are some plans
http://media.wix.com/ugd/4589f4_0560559bd4b84e05a4e0b1ff69f72269.pdf
Bird is the word!!!
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