Friday, August 27, 2010

A Seasonal Ending

The Eastern Bluebirds have finished their nesting season here at the garden. Some of the juveniles continue to fly to the boxes where they began life. That's normal. One wonders if they like to check out the old homeplace just like people do, but we have to be careful not to anthropomorphize - apply human characteristics to animal behavior.

At the beginning of the season we tried something new, hoping to encourage the birds to use more of the boxes. We placed inserts made from egg cartons inside on the bottom of each box. Out of the thirty-three boxes on the trail, twenty-nine boxes had bluebird nests in them. This is an eight percent increase of box use over last year's activity. However, numbers don't always tell the whole story so we aren't going out on a limb to recommend using inserts. Bluebirds, like many other birds, often build nests and never use them. There were many perfectly made nests that never had eggs laid in them. Also, there were many eggs laid this year that never hatched. The parents just seemed to have abandoned those nests. It could be that the extremely high summer temperatures caused the eggs to fail to develop. In all cases, the eggs had discolored and we removed them along with the nests.

However, there was an increase in the number of birds that fledged. This year seventy-one fledged. That's a slight increase over the previous year when sixty-seven new "blues" graced the garden. Again, there were predators that invaded the nests, probably snakes and raccoons. One box was attacked by fire ants. These things are disturbing but, at the same time, nature has its own way of keeping life balanced and we keep that in mind.

Having said that, we are encouraged that over the last three years there has been an increase in nestbox use and the number of birds fledged. Young birds often stay in the same area where they hatched and fledged so it's logical that they would mate and reproduce here at the garden. For now they are still enjoying a season with lots of insects to catch but, come fall and winter, their diet will change to berries and other small fruit. During the cold nights they will snuggle together inside those nestboxes for comfort and warmth. Our monitoring is completed for this season, but we'll start again - along about the middle of next March.

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