Saturday, February 12, 2011

Bluebirds depend on birdhouses

Our club of dedicated volunteers maintain about 5000 birdhouses in the Calgary area. Most are set up on fence posts, three per mile. Because of these, about 1000 Mountain Bluebird pairs nested in 2009.

Monday, January 24, 2011

Calgary Area Nest-box Monitors Report 2010

Copies can be found by contacting
Editor Bill Taylor or Don Stiles

Weather 2010 for Calgary Area Nest-box Monitors

Half the monitors this year blamed the long wet spring (from March to September) for the poor productivity of nest-box inhabitants. My email was full of comments like Ron Reist’s “…huge number of failed TRES nests due to inclement weather (lack of food for both adults and young.)” The weather was harder on Tree Swallows (TRES) especially as they require mainly air insects. Mountain Bluebirds (MOBL) can adapt by eating ground and air insects, berries, etc. I suspect many parents simply gave up as they could find barely enough food for themselves – and even then there were more dead adults this year than usual. The cold contributed to hypothermia, and the excessive rain and hail probably caused some deaths as well. None of us enjoy opening a box to find several dead hatchlings, but there isn’t much we can do. Lynda Alderman comments that this “was a very confusing and sad year to do the route. [the Bluebirds’] struggle in June was hard to witness......rain, cold, snow, no bugs and then the swallows. Nature took its toll.”

We may not be able to help our avian friends in the cold weather, but they sometimes help each other. Shonna McLeod relates this story:
This box was occupied by a family of Mountain Bluebirds and they had successfully hatched 6 fledglings which I had previously banded the trip before.
Checking the box to see if baby Bluebirds had fledged, I was astonished to find an adult female TRES with wings spread out over the young hatchlings of another species, dead on top of them.
It was a picture I will never forget and it made me very sad to realize that the instinct of the TRES female to protect the young from the cold was intact even though the babies were not her own young.
I wonder if anyone else has ever documented anything like this.

Racoons 2010

Raccoons and some other predators also caused damage this year. Marijke Jalink-Wijbrans noted “…a raccoon discovered our trail and dined on about 47-65 young Tree Swallows.”

How can we guard against raccoons? We have been recommending driving a screw into the base of the box in order to prevent a raccoon’s pushing up the base. Even this may not be enough. We may need two screws in those areas where raccoons are prevalent. Many years ago they were only south of the border, but they are moving north! Climate change?

House Wrens 2010

House Wrens were in great number (209 nests) again this year – twice the number (105) of House Sparrows. They are protected by wildlife legislation so we can’t take aggressive measures. The best prevention is to place our boxes well away from trees and shrubs. I had one box where a wren pierced all 6 MOBL eggs and pushed them out of the box before filling it with twigs. I actually observed the normally passive MOBL pair later chasing the wren when he tried to take over another nearby box, which the Bluebirds were using as a replacement nest. Aggressive Bluebirds! What’s next?
Diane Leonhardt observed: Wrens seemed to be more aggressive this year… they destroyed several nests on our other trails.

Monitors and Boxes and Routes 2010

We have many reporting monitor teams (at least 83 people) who covered the 4,734 boxes in the Calgary Area. These include several new to the CANM this year. Welcome to Matt Ginn, Jack Borno, Susanne Maidment, Jennifer Hilborne, Cindy and Tim Jacob, Anne Gerencher, Mike Risely, Donna Wieckowski, Sue Konopnicki, Mary Jane Hunter, Mike Truch, Darrel Bender, and Colleen Rittwage. Some of those took over parts of George Loades’ trails. Those were big shoes to fill! Others picked up trails of retiring or downsizing monitors: Gail Visser, Margaret Adams, Don Conrad, and Bill Ritchie and Al Reynar (who both passed away in November 2009.) Thanks to all of you for the work you do for our birds.

Five monitors reported on two trails, and we had 64 trails covered this year. And that is probably very conservative, as some of us lump several “trails” in one report. The average length of trail was 30.4 km. To access these trails, some monitors had to drive considerable distances. The average round trip reported was 112.2 km. (Some ten trails did not report the length of the round trip.) Consider that some of us visit each box as many as 8 times a year. That mounts up to a lot of “mileage” driven in the interests of birds (“kilometrage” doesn’t sound right to me!)
The average trail, 80 boxes, contains 2.44 boxes per km. Does that seem about right for density of coverage? Seven monitors have not yet reported the length of their trails, and these trails amounted to 507 boxes. Perhaps next year we’ll have a more complete picture! I do appreciate all of you who have taken the time and trouble to measure your routes – both the length of the trail from first to last box, and the round trip from your home to cover your trail.

Monitor Comments 2010

Monitor Comments
I thank all monitors who took the time to send some comments and pictures of their routes. It is very enjoyable to read these, and I share some comments with you:

Wim and Marijke Jalink-Wijbrans:
This year’s raccoon was so strong he pushed up the bottom … and bent the screw!

At the start of the season, we found 9 dead adults in boxes, more than before…

Five of the 6 female MOBL had returned to the same nest as last year.
Photo Bill Taylor
Ron Reist
starting this year I am pairing all boxes that have a history of MOBL use
and reducing to singles all boxes which had only TRES history - hoping to
increase my MOBL success rate.

Mallard eggs near TRES box photo Linda Wiggins

Brian Exton
I had only one second brood instead of multiple second broods as I have had in the past.

Diane Leonhardt
One trail will be moved as the owners decided to pasture their horses on the land we were using. Is there any proven deterrent for horses?
The birds seemed to be playing musical nest-boxes on one portion where the BB and TS kept switching boxes for about 3 weeks.

Jean Dunn notes this happy occasion:
I did have one nice experience the last day I checked the trail on Sept. 2nd and that was to see two "flocks" of young bluebirds gathering on the telephone wires as if to say good-bye to the area. They took off after I had stopped and counted them and it was a nice good-bye for me too.