Ontario Eastern Bluebird Society

 

2001 Fall Newsletter

Welcome to the Fall Newsletter. The AGM is set for Saturday March 16th 2002 at the Royal Botanical Gardens in Burlington Ontario. This will be our 12th annual meeting since the first in 1990.

Many trail operators reported disastrous early nestings with very few bluebirds fledging successfully. The period from May 22nd to June 1st was very cold and wet which resulted in high nestling mortality. Although the May 2001 mean temperature was 1.2 C above the normal, from May 21st to May 30th it was cold with rain on every day except two. Most of the nestling mortality occurred during this period. There were reports of tree swallows killing EABL young by pecking them on the head while the adult EABLs were desperately looking for food to feed them. This made it difficult to defend the nest. On my trail every available box was occupied by tree swallows putting additional pressure on the nesting bluebirds. I have never witnessed as many pairs of tree swallows as I did this year. They had their best year ever since I began monitoring in 1980.

June was warm allowing EABLs that had failed first nestings to renest successfully. Early July (1-6) was unseasonably cold with bitter northwest winds. The mean temperature for the first six days never reached the mean for the month and on three of the days, the minimum temperature was in single digits. There were several reports of failed nestings during this period especially with box openings facing northwest.

Most of Canada experienced a severe drought this past summer possibly worse than the summer of 1961 according to David Philips, Environment Canadas senior climatologist. The initial weather data for July shows Southern Ontario and Quebec received 45% less precipitation than normal.

It is very important during the early part of the nesting season (until early June) to have your nestbox completely sealed, with all ventilation holes closed. I do this using duct tape, which is removed later. Any hole allows wind to slice through the box causing severe hypothermia and death for young bluebirds and other cavity nesters. They are particularly vulnerable at about 6-8 days old after the female stops brooding them at night and before their thermo regulation abilities have fully developed. All box entrances must face to the southeast to block northwest winds.

It was the driest summer on record for Waterloo-Wellington County. See Temperature Rainfall chart for 2001 below.

Temp Rainfall Spring and Summer 2001

 

Temperature

Rainfall (Snowfall)

Month

Mean Normal* Actual Normal*
May 13.7C 12.5C 75.8mm 76.3mm
June 18.5C 17.0C 53.7mm 79.5mm
July 19.4C 19.9C 20.3mm 90.4mm
August 21.0C 18.7C 57.8mm 93.3mm

*Normal based on long term 30 year average. Information gathered at Waterloo-Wellington Regional Airport by Environment Canada. Weather data compiled at the Waterloo-Wellington Regional Airport Environment Canada weather station.

 

August was very hot with record breaking temperatures during the first nine days of August with the maximum temperature over 30 C on every day except August 4 (29.9 C). It was also the driest summer on record for Southern Ontario. I had one brood of young that did not fledge until August 22nd. They survived the record setting heat as nestlings and fledged successfully. During this period, I checked them daily in the early evening. They looked dehydrated during this period with their fecal sacs almost completely dried up (water was reabsorbed). I arrived on Friday August 10th with meal worms and small crickets that I left inside the nestbox but by that time, they had survived 5 days in a row of record heat.
Ventilation is important but during the first half of the nesting season, the nestbox should be completely sealed except for the entrance hole (facing SE). Kestrel boxes require the same treatment. Cold weather affects bluebirds to a greater extent than extreme heat.

House wrens caused problems for EABLs this year throwing out both eggs and newly hatched young. Upon visiting a nestbox near St. George that should have had newly hatched young, I found the nest empty. The nest was intact with very little indication of disturbance.

In cases like this, I carefully examine beneath the nestbox for any signs of predators. Sure enough there were four one-half to one day EABL chicks on the ground, 3 alive and 1 dead. Since it was early in the morning they had been there probably less than 1 hour. I put them in the box and lowered the nest. The parents continued feeding and all three fledged. They had been removed by a house wren and dropped below the nestbox. House wrens were nesting in a box beside the bluebirds. Because only a few house wrens nest in the orchards, and being late nesters, they usually cause very few problems. This year was different with at least 3 sets of eggs destroyed.

Another interesting observation by trail operators was that house wren numbers were only one half of what they were last year (Don Wills Personal Communication). House wrens, even though they cause problems, are fully protected by law, ONLY house sparrows and starlings can legally be removed and humanely destroyed.

Hope to see everyone at the annual meeting on March 16th, 2002.

Bill Read

 
 

Ontario Eastern Bluebird Society

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