Jeff explained that several other species of birds are also cavity nesters and compete for the use of the houses, including Tree Swallows, House Wrens and House Sparrows. Each of these species builds a distinct type of nest. Bluebird nests are woven from grass; Tree Swallow nests are similar but include feathers. House Wrens build nests of sticks that nearly fill the whole box. And the nests of House Sparrows contain bits of just about anything they can find including paper, plastic and string. Although Bluebird conservation is the primary reason for the trail, all these species except the House Sparrow are protected species and their nests are left undisturbed. House Sparrow are non-native invaders and thus they are not protected like the other songbirds. Monitoring is done at least weekly to remove the Sparrow nests, or else they would monopolize all the houses.
Bluebirds, as well as the other species, can have two or sometimes even three successful nests in a season. Our walk came after the second fledging and we checked to see if there were any signs of a third nesting. Most of the houses were empty, but one had a current House Wren nest in it with eggs.
Our trip also provided us the opportunity to see the Biocore Prairie in its full glory, with many prairie species in full bloom, as well as a short diversion into the Community Gardens to see the diversity of gardens that have been planted there.