by Alex Forsythe
Despite its name, Prairie Warblers are not typically found in prairies or in back yards. As an early successional species, they prefer large brushy areas and young trees. They are not widespread in Indiana, and even the earliest records of sightings are few. Prairie Warblers were first recorded in the northern half of Indiana in 1892, with one recorded in Wabash on May 2, 1892 and two in Lebanon on April 29, 1892. In that year, the Prairie Warbler had only been reported in four locations across Indiana. (Amos Butler, Proceedings of the Indiana Academy of Science, Volume 3, 1893).
This tail-wagging little bird has been featured on several postage stamps, including stamps in Grenada, Barbados, British Virgin Islands, and most recently in St. Kitts. In 1951 the National Wildlife Federation offered Peterson’s illustration of a Prairie Warbler in the form of a collectible conservation stamp, and American Bird magazine offered slides of male, female and nestling Prairie Warblers for $0.50 in 1903. For the more gruesome, barbaric collector, you could buy a Prairie Warbler skin for the low price of just $0.15 in 1895. That was a bargain compared to the cost of a Bald Eagle at $6.00. (Natural Science News, Volume 1, October 5, 1985).
Thankfully we no longer shoot songbirds and sell the skins as collectibles. Nevertheless populations of many birds remain in decline largely due to human activity, loss of habitat, predation, and parasitism. The USGS North American BBS (Breeding Bird Survey) Population Trend Map for 1966-2013 shows an unmistakable decline in breeding Prairie Warblers in several states including Indiana. Between 1966 and 1993, the Midwest had an alarming 44% decline in breeding Prairie Warblers, and an overall 66% decline from 1966 to 2014. By the way, I confess I have a bit of an obsession with these BBS Trend Maps. I am in charge of the BBS for Adams County, and I assist with the BBS in Wabash and Huntington Counties, so I look at the Trend Maps often. Even if you are not helping with the BBS, I would encourage you to take a look at the Trend Maps for your favorite birds. You might be surprised. Incidentally, when the map indicates a percentage decline, that’s not the total decline. It’s a yearly decline. A “-1.5” indicates that the population dropped 1.5% each year from 1966 to 2013. Those declines add up!
Indiana University professor Val Nolan, Jr. studied the Prairie Warbler populations extensively and wrote a book in 1978 about his findings: “Ecology and Behavior of the Prairie Warbler”. His findings were troubling. The nests he studied suffered 24% parasitism by cowbirds, only 69% of the warbler nestlings survived to adulthood, and the annual female mortality was 35%. Using those numbers, he calculated that the population would barely replace itself. The U.S. Forest Service has conducted a more recent study of the Prairie Warbler and found that the biggest cause of the decline is no longer the cowbird, but habitat loss. (Conservation Assessment for Prairie Warbler, U.S. Forest Service 2001).
Fortunately, several Prairie Warbler habitats are being preserved. I found the bird in this photo happily residing at the Indiana Dunes last spring. New Jersey has set up a 1200-acre preserve specifically for Prairie Warblers: the Michael Huber Prairie Warbler Preserve.
If you decide to go in search of a Prairie Warbler, and if you bird by ear, take note: Prairie Warblers have two distinct songs. One song is used for courtship while the second song is used to mark territory. An excellent video of a Prairie Warbler singing his heart out can be found here: https://www.youtube.com/