Wildlife Conservation: All Along the Water Tower

Peregrine falcons are a cliff-nesting species whose populations were significantly reduced in the 1950s as a result of environmental contamination by the pesticide DDT. This dangerous chemical accumulated in adult birds and caused thin-shelled eggs, which broke during incubation. The population declined rapidly and by the early 1960s, peregrine falcons were extinct in the eastern U. S.; the last known pair nested in Michigan in 1957. It was one of the first species listed by the Endangered Species Act in 1973.

An effort to reintroduce peregrine falcons into urban environments began in 1982 when chicks were released, or “hacked”, from buildings, bridges and other man-made structures in cities throughout the eastern U.S. Because they strictly hunt birds, peregrines find ample prey in cities with their abundance of pigeons, doves, starlings and other city-dwelling species. This successful reintroduction effort led to peregrines nesting in cities throughout the Midwest and a growing population not only in cities, but in much of their former natural range such as the cliffs along Lake Superior. The now wild peregrine population did so well that they were removed from the federal endangered species list in 1999.

Peregrines currently nest at a number of locations in southeast Michigan including in Warren, Pontiac, Southfield, Grosse Pointe and seven different sites in Detroit. They nest in other Michigan cities as well including Grand Rapids, Lansing and Jackson. Many of the chicks are banded with unique combinations that allow for individual identification when they mature and establish their own nests. Locally, the Detroit Zoological Society’s (DZS) veterinary staff works with the Michigan Department of Natural Resources (DNR) in the banding effort by performing health assessments as bands are put on pre-fledged chicks.

This past summer, DZS staff and local birders noticed a pair of peregrines perching on the Detroit Zoo’s iconic water tower and hunting pigeons at the Zoo and in Royal Oak. While difficult to see, the male was identified as Justice, a bird hatched in 2012 at the Jackson County Tower Building with a band combination of black/red, 08/P. The female is not banded so we do not know her age or hatch location, but they are a well bonded pair that is still observed around the Zoo.

Often when a pair of peregrines establish a territory such as the water tower with plentiful prey nearby, they will end up nesting at that site. Peregrines lay their eggs on gravel or dirt with minimal nesting material. Because the water tower did not have a proper area for the birds to build a nest, DZS staff worked with the DNR to design and construct a nest box that will meet the needs of the nesting birds. The box was recently installed on the water tower, which was not an easy task. The box is on the southeast side to offer protection from the wind while exposed to ample sunshine. It is visible from the westbound service drive as you wait for the light at Woodward.

We are thrilled that peregrines have chosen the Detroit Zoo as a home along with other native birds, such as the turkey vultures, great blue herons, double-crested cormorants and even the occasional visiting bald eagle. We are optimistic that peregrines will join the species that also nest at the Zoo, which includes wood ducks, green herons and the highly visible breeding colony of black-crowned night herons, a species normally found in secluded wetlands.

– Tom Schneider is the curator of birds for the Detroit Zoological Society.

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