The Bermuda Bluebird (Sialia sialis) is an indigenous species to Bermuda. These vibrantly coloured birds have a rich history with the island, and Bermuda is the only place outside of North America where the birds are known to breed. Bluebirds flourish with large expanses of open space (such as golf courses) present, which enables them to find food. As such, when settlers began clearing land for open pastures and fields, the birds were common; occurring in greater densities than their populations in North America.
However, the introduction of the House Sparrow in the 19th century caused a decline in bluebird populations since both birds competed for hole nesting sites. Endemic cedar trees became the bluebird’s only nesting site, and so the cedar scale epidemic in the 1940s left bluebirds homeless. The House Sparrow continues to be the most numerous bird in Bermuda today, however Bluebirds are making a comeback due to human aid.
Recently I undertook a community service initiative with some of my friends to help the bluebird by constructing and erecting bluebird boxes. We raised money to buy materials for building boxes, built them, painted them, and, with the help of a friend in charge of a bluebird trail, erected them. It was amazing to see that mere minutes after we had put up a pole and attached one of the boxes we made, a pair of bluebirds were already checking it out!
Bluebird numbers are back on the rise, however they now nest exclusively in bluebird boxes which are designed by the Bermuda Bluebird Society. These boxes are ideal nesting locations and the entrance hole is only large enough for a bluebird’s small body to fit through, preventing invasion by larger Kiskadees or Starlings. However, sparrows, being smaller than bluebirds, can fit in to the box and monitors of a bluebird trail must clean out a sparrow’s nest if it is found in a bluebird box.
It is amazing how birds can be told apart by their nests. Kiskadees will build a large, messy nest out of anything they can find, including trash. Sparrows build a slightly neater nest, still constructed with plastic trash, and surrounded by feathers. Bluebirds, conversely, build an extremely neat cup-shaped nest out of either grass or casuarina needles.
Bluebird males are more vibrant than females in colour with a blue back and tail and a red breast. Females are more brown in colour. They usually lay a clutch of 3-5 light blue eggs which take about two weeks to hatch. The hatchlings take between 15 and 20 days to fledge. Before they are able to feed themselves, hatchlings are fed insects and invertebrates by their parents. Though it seems obvious that a larger clutch of eggs would be desirable in order to restore bluebird numbers, it’s often the case that if more than four eggs are laid, the parents will be unable to feed such a large number of chicks.
With the help of the Bermuda Bluebird Society and people who erect boxes or monitor trails, bluebird numbers are expected to increase. I’ll be returning to St. Georges with my friends to check back on the boxes we put up and it’s possible that some of them may be inhabited as the bluebird nesting season is March through July.