Important Bird Area

Rare Species in the Wye Marsh Wildlife Area

Submitted by: Jon French

Thursday, September 06, 2001

In early June 2001 research began in the Wye Marsh Wildlife Area funded by the Important Bird Area’s Community Action Fund and the Ontario Ministry of Natural Resources’ Species at Risk Funds. The field season has now come to a close and the final report is in its first draft form.

Four other significant wetlands in Severn Sound were investigated during the research this year, Tiny Marsh, Matchedash Bay, Sturgeon Bay and Hog Bay. Severn Sound is located in the South Eastern corner of Georgian Bay on Lake Huron in Ontario.

The species of concern for the research were two designated species at risk in Ontario, the Least Bittern (Ixobrychus exilis) and Black Tern (Chlidonias niger). Monitoring the population and nesting success of the Trumpeter Swan (Cygnus buccinator) was also carried out (8 nesting pairs were confirmed in 2001 at the Wye Marsh Wildlife Area).

Although well known for providing a home and managed breeding program for the Trumpeter Swan, the Wye Marsh Wildlife Area is also a provincially and nationally significant breeding habitat for the Least Bittern and Black Tern. Jon French, also a naturalist at the Wye Marsh Wildlife Centre, is carrying out the research with expert support from Bob Bowles and the Canadian Wildlife Service’s Chip Weseloh and Kate Jermyn. (Kate Jermyn carried out the Black Tern nesting and Least Bittern territory mapping and breeding research at Wye Marsh in 2000, which contributed to the Wye Marsh Wildlife Area’s designation as an IBA (Important Bird Area).)

The days in the field for 2001 provided us with the knowledge that there are significant numbers of both Black Terns and Least Bitterns nesting in the Wye Marsh. Under the aggressive protests of the adult Black Terns, their nest count reached forty as of late July which is at the far end of the nesting season for the Tern’s . On average there are two or three eggs in a full Black Tern clutch, most commonly 3. Many of the nests had successful hatches and several fledged young have been observed in the nest colony site, bearing their immature colors of a white breast, grey mottled head and body and light grey wings. The young Black Terns are quick to leave the nest site, at one day (24 hours) after hatch they are capable of fleeing the nest platform that is generally a precariously floating mat of submergent or dead vegetation quite exposed in an area of hemi-marsh (half open water and half vegetative cover generally speaking).

Although less vocally and physically aggressive compared to the Black Tern, the Least Bittern has chosen an alternative strategy for nest success, stealth and invisibility. These smallest of the Heron family, are by nature secretive and well camouflaged by color and form. Our count of Least Bittern nests reached an astounding fifteen. Twelve of these nests were found in a small, managed area of the marsh known as the Preston Cell. The nests have been found on small platforms supported by dense emergent vegetation with a woven canopy shading the platform. All nests were found within four meters from an open area of clear water (a channel with little vegetative growth on the surface). A full clutch in the Least Bittern nest is on average four to six eggs. Ten of the fifteen nests were confirmed to have successful hatches determined by the identification of at least one immature bird at or near the nest site. Their ability to disappear into the tall vegetation allows them to leave the nest before they are able to take flight, using their legs as the main mode of mobility.

The data gathered from the research has been contributed to the Natural Heritage Information Center of the Ontario Ministry of Natural Resources and the Ontario Nest Records Scheme of the Royal Ontario Museum.

Please call or visit the Wye Marsh Wildlife Centre with any questions regarding these birds or the research carried out at the Wye Marsh Wildlife Area.

Thank-you to the volunteers helping in this research; Nancy Sheppard, Tamara Flannigan and Haido Liotos.