Calgary Area Nestbox Monitors
Detailed Procedures and What to Expect
- Where to set up your nest boxes - Most Calgary area bluebird trails are set up along roadsides, by attaching nest boxes to fence posts with screw or nails. A suggested spacing is 300 to 400 metres, or 4 to 5 nest boxes per mile, although this can vary depending on habitat or farm buildings, etc. Ideal habitat would include native pasture land for bluebirds to find insects plus nearby aspen poplar trees for shelter. Nest boxes should be set up in open areas, and if possible, over 400 metres from farm buildings. Nest boxes near farm buildings are prone to house sparrows. Nest boxes set in or near trees are more apt to attract house wrens. Most nest boxes not occupied by bluebirds will have tree swallows which are also desirable insect eating birds. A preferred direction for the nest box hole to face is east or south. This will prevent rains accompanied by strong north and westerly winds getting in the nest box.
- By May 25, most of the mountain bluebirds females will be incubating eggs. A suggested procedure is to approach the nest, put your hand over the hole, open the box, gently lift out the female, count the eggs, put the female back on the eggs and close the box. She is generally very docile when brooding and will usually go back to brooding. You can check the bird's legs for a band when you have the bird out of the nest, and if you find one, record the number. By this week most of the tree swallows will have started their nest building, and you will generally see one or more tree swallows in the vicinity of the nest. If you do not see any birds near the nest, you may identify the nest using the next section, "How to Identify Nests and their Contents". This will also help identify two other species sometimes found, the house sparrow and the house wren. House Sparrows are non-native birds and will displace the other desirable native birds you want to attract. It is recommended that their nests and contents be removed, and that the adult bird be disposed of it you catch it. This may enable a bluebird or tree swallow pair to later nest in that box.
- By June 12, most of your bluebirds will have hatched so you will be counting young. Expect most eggs to hatch, although it is not uncommon to have one infertile egg in the nest. Determining what stage your nestlings are at is described under "Young" in the next section, "How to identify Nests and their Contents". A few of your bluebirds which have started late or have failed in their first nesting will now have eggs. Most of your tree swallows will have laid eggs. To count the eggs, follow the same procedure as given above for bluebirds.
- By June 30, your tree swallows will mostly have hatched and you will be counting young. In some cases, your bluebirds will have started second broods, so you can expect to see eggs from these. Percentage of second broods varies from 10 to 50% in the Calgary area, with an average of about 25%. If they get started early in the season, there is a greater chance of second broods.
- By July 15, most of you tree swallows will have fledged, and you will be counting the young from your second broods of bluebirds. You may clean out nests from fledged broods at this time if you wish.
- By Aug. 1, nearly all of your young will have fledged. You will be looking for infertile eggs missed earlier and also dead young. Occasionally, a late brood of bluebirds or tree swallows will be found. You may clean out all inactive nests at this time, if desired, as further nesting is unlikely.
