Waterbirds make a splash
Research scientist and recently graduated master’s student of the Forest Park Living Lab, August Wise led an investigation into the waterbird community of Forest Park for his master’s thesis at Saint Louis University. What did he uncover?
A snowy egret wades deep looking for a tasty snack near Picnic Island in Forest Park. While globally stable, the snowy egret is an endangered summer resident in Missouri.
Waterbirds include many species like the classic mallard (Anas platyrhynchos) and the infamous Canada goose (Branta canadensis). Here in the Saint Louis region, waterbirds also include lesser-known species such as the snowy egret (Egretta thula), a state endangered wading bird with long black legs and bright yellow feet, and the chicken-like American coot (Fulica americana), a marsh bird with large, lobed toes. He wanted to know how many species of waterbird use the park, how many of these are of conservation concern, and what characteristics of the park make it an enticing spot for the local waterbirds to spend their time.
Research assistant Elizabeth Schwartz prepares to measure a crayfish, one of several prey species caught during trapping.
He, with help from 16 research assistants from Saint Louis University, conducted two years of waterbird surveys across the park, using a standardized protocol to record the presence of individuals from each species. They found that Forest Park boasts over 38 waterbird species, or over 60% of all waterbird species ever found in the greater Saint Louis region. Of the 13 species in the region of conservation concern, they observed 9.
Two male ruddy ducks swim past Wildlife Island to join a third out of view. Ruddy ducks are the only stiff-tailed ducks native to North America, and males develop a bright blue bill during the breeding season.
To understand what made the park so alluring to these birds, they documented many pond features, including water depth, water quality, prey availability, and human activity. August then compared these features to bird diversity in each pond. For “diversity”, he looked at not just how many species were present (species “richness”), but also the relative number of each species (species “evenness”).
Research assistant Riley Tharp prepares a water quality sample for analysis.
Out of all the features tested, two stood out as the strongest determinants of waterbird diversity: Ponds that were shallower, and ponds that varied more in depth had higher bird species diversity. This could be due to wading birds’ need for shallow depths in which to wade while hunting, and for diving birds that can corner fish in more numerous, deeper wells below the surface of ponds with greater depth variation. Our work to better understand what pond features matter most to these waterbirds will inform future park management- to help create an even more inviting place for both humans and birds alike.
A great blue heron takes a nap while overlooking Jefferson Lake from a nearby bald cypress tree. The most common heron species, it is also the only one that is a year-round resident of the region.
We continue to monitor ducks and geese in Forest Park using GPS tags to map their movements and determine how they spend their time in the park.
Two male hooded mergansers float in Post-Dispatch Lake, near the Boathouse. Hooded mergansers are a winter resident of the region and dive underwater to hunt for prey.