The Cerulean warbler is a small, migratory songbird known for its bright blue coloring. Males and females are similar in size, but differ slightly in plumage. Both sexes have beautiful blue feathers with white bars on its wings and white spots on its tail. Males have streaks on its back and, when breeding, are more brightly blue with a blue-black neck ring. During the breeding months, females tend to be a more bluish green with a white to yellow line over the eye.
Though bold in coloring, these small warblers are not easy to spot. Their love for large trees and an open understory have them living and breeding high in the canopies of large continuous tracts of deciduous forests. In Indiana, they greatly prefer the Brown County Hills, an area known for its large blocks of forests. They may be hard to spot, but when present, Cerulean warblers can be heard clearly. Listen for their loud call of “zee zee zee zizizizi eeet” and look up.
As neotropical migratory birds, Cerulean warblers aren't found in Indiana year round. In the summer months, during their breeding season, they are found throughout the eastern United States and Canada. As winter grows near, the Ceruleans will migrate anywhere from 2,175 - 4,500 miles to the warmer climates of northwestern South America. Like many migratory birds, these warblers will make this long distance trip to be in a location where food is plentiful and the chances of breeding success are greater.
While their breeding range is fairly large, there is special concern of population declines due to habitat destruction, fragmentation and land modification in its breeding and migratory areas. The loss of suitable habitat - like the large areas of contiguous mature forests - threatens the Cerulean warblers the most.
The Cerulean warbler is not the only bird that relies on large forests. Just a few other forest dwelling birds include the Yellow-billed cuckoo, Pileated woodpecker, Wood thrush, and Scarlet tanager. The Nature Conservancy works to ensure that the forests needed by Cerulean warblers, and many other birds, are permanently protected.
Interesting Facts about the Cerulean Warbler
- Female Cerulean warblers are known "bungee jumpers". When leaving its nest, she will drop for the side, keeping her wings close to her body. Only when she is well below the nest does the female open her wings to fly.
- If the first nest fails, then the female will build a new nest. Though most of the lining is newly gathered, the female will spend the time to taking out any spider webs used in the first nest. The warbler will reuse this particular material because it is a valuable part of the nest's construction and too time-consuming to waste.
- Cerulean warblers feed mostly on insects by gleaning them off the leaves of the trees they inhabit. In the winter, plant material may also be consumed.
- The lifespan of the Cerulean is unknown though records have shown them to be as old as 6 years.
- Cerulean warblers are found in mixed-species foraging flocks when wintering in South America.
- High in the trees, there is less competition for food with their avian counterparts. The threat of being prey to ground-dwelling predators is also greatly reduced. Despite these facts, the population of Ceruleans is still decreasing.