In the animated motion picture "Muppet Movie,” Kermit laments in a well-known tune, "It Ain't Easy Being Green.”
Mississippi State researchers are finding that the fictional frog's problem is shared by a real-life wetland inhabitant whose distinctive green crown and multi-colored breeding plumage cause many to regard it as the continent's most beautiful duck.
The North American wood duck also happens to be one of the Southeast's most popular waterfowl. A distinctly North American species, it's now the subject of a recently released report on duckling survival rates completed by scientists at the university's Forest and Wildlife Research Center.
"To understand early survival of wood duck ducklings, we looked at factors ranging from the age of the mothers to the predators that feed on ducklings,” said wildlife and fisheries professor Richard Kaminski. "Habitat use also was an important part of the study.”
Over a four-year research period, Kaminski, co-investigator Bruce Leopold, and graduate student team members found that more than 90 percent of the brooding wood duck females survived. Sadly, only about 20 percent of their offspring ever reached adulthood.
To gather information, MSU investigators fitted radio transmitters weighing less than one-tenth of an ounce to more than 130 nesting females and 400 ducklings in the Noxubee National Wildlife Refuge of East Mississippi and the Aliceville Lake of the Tennessee-Tombigbee Waterway in West Alabama. Movement and survival data was collected by then-doctoral student Brian Davis, under the direction of Kaminski and other faculty members.
Davis, a Sorrento, Ill., resident who graduated last December, utilized the study in completing his required doctoral dissertation. He now works for Ducks Unlimited as a regional biologist in Arkansas.
In the Forest and Wildlife Research report, Davis identified predators to be the primary cause for low duckling survival rates. "Birds, including hawks, owls and herons, devoured a large percentage, while aquatic predators, including spotted gar, snapping turtles, alligators, and even cottonmouth snakes, also took a significant toll,” he reported.
Additionally, Davis observed that a major factor in the loss rate had much to do with a well-intentioned change to the birds' nesting habit introduced by humans in the 1930s. To help the waterfowl deal with increasing natural habitat loss, man-made boxes were substituted for the natural tree cavities ducks instinctively seek as predator- and flood-proof sites for laying eggs and rearing young.
"Clearly, nest boxes help rebuild populations that almost were exterminated by over-harvest and habitat losses,” Davis said. "However, because boxes often were placed close together in areas lacking adequate vegetative cover, the ducklings became easy predator targets.”
Duckling survival rates average more than 70 percent in habitats with a dense cover of scrub-shrub vegetation and forests, the study found. This compares to a 12-43 percent range in wetlands with a concentration of man-made nest boxes.
"We may be able to enhance wood duck duckling survival rates by better dispersing nest boxes in scrub-shrub habitats such as buttonbush and willow,” Davis said. "Losses to predators also may be reduced by establishing these habitats adjacent to existing nest boxes.”