Posted on 27 February 2014.
Photo by Phil Hauck.
Prior to European settlement the Common Grackle was likely not common. It wasn’t until settlers started clearing land for agricultural uses that the species start expanding, and rapidly. By 1974, the species global population had reached 190 million individuals (National Audubon).
The Common Grackle is part of the blackbird family and if you live in an urban area chances are you have seen one or an entire flock. This grackle looks black from a distance but up close they display a glossy purple head, a bronzy-iridescent body and bright golden eyes. In Michigan, they prefer larger cities including Detroit, Lansing, Jackson, Grand Rapids, Gaylord, Clare and Sault Ste. Marie. The species is most often found in open to partially open areas with scattered trees, usually along forest edges. The Common Grackle particularly prefers human-altered habitats.
Although once widespread, the species has witnessed a 61 percent decline in population numbers since 1974, making the current global population roughly 73 million individuals (National Audubon). In Michigan, the decline is not as drastic, with a 2.5 percent decrease annually from 1988 to 2008 (Michigan Breeding Bird Atlas I & II). Partners in Flight estimates that in the state the Common Grackle population is around 1.6 million individuals, making it one of the more common birds in Michigan.
Its commonality along with its current population decline has landed the Common Grackle on National Audubon’s list of “Top 20 Common Birds in Decline”. The species decline is due to two different elements.
Common Grackles often roost in large numbers around agricultural food sources such as corn, soybeans and cherries, which has caused the species to be considered an agricultural pest allowing it to be legal to eliminate the bird in some areas. According to the Michigan Breeding Bird Atlas the depredation order, “allows the control of Common Grackles in agricultural situations when found committing or about to commit depredations upon ornamental or shade trees, agricultural crops, livestock, or wildlife, or when concentrated in such numbers and manner as to constitute a health hazard or other nuisance.” (Depredation 2008). When grackles roost at the same site for several consecutive years the site has a chance of harboring the fungus, Histoplasma capsulatum, which can be fatal in humans because it causes histoplasmosis, an infection of the lungs.
The second reason for the population decline is due to the bird’s shrinking habitat. In the late 1800’s and into the 1900’s land was being cleared at an astonishing pace, opening up an abundance of habitat for the grackle. Now with reforestation in full swing, the Common Grackle is witnessing a large, quick habitat loss.
To help the Common Grackle improve its population numbers check into the federal, state and local regulations on agricultural pests. If you live in an area with large numbers of blackbirds investigate what the protocol is regarding blackbird control and then contact the U.S. Fish and Wildlife Service or your state wildlife office; if permits have been issued report the information to the email@example.com.
Additionally, participating in bird surveys such as the Christmas Bird Count, Great Backyard Bird Count and the North American Breeding Bird Survey will help scientist get a better idea of the species overall population. Lastly, if you submit checklists to Cornell Lab of Ornithology’s citizen scientist project eBird, make sure to include all birds you observe, even the species you think are common, you never know when they will be in decline.