MIDLAND -- The Wye Marsh is home to dozens of species of birds, but depending on the season and their habitat, those numbers are continually changing.

On Saturday, Wye Marsh Wildlife Centre in Midland hosted its annual Christmas bird count for kids; it’s an event Jennifer Pelletier with the Centre says is an introduction to the local species.

“We saw black-capped chickadees; we saw blue jays, trumpeter swans, American black ducks and mallards,” says Pelletier, who adds the Citizen Science Conservationists have used the count to monitor the population, “we are able to see changes that are taking place over time within a location.”

In some cases, those changes have been dramatic. According to the North American Bird Conservation Initiative, grassland species and aerial insectivores like swallows have declined by nearly 60 per cent since 1970.

“Everybody can play a role in it,” says visitor Andrew Lodge, “getting the science, getting the data seeing the numbers because its trends over time and you can be nerdy about it, but seeing that trend over time is so important.”

The numbers also reveal some good news. Waterfowl numbers have been growing, while the number hawks and eagles have also increased since DDT was banned. The evidence of that can be seen on Saturday.

“We did see a rough-legged hawk flying over the marsh, which is not common,” says volunteer Ashlea Veldhoen, “and I think it was the first sighting of that species at the marsh which is very interesting.”

The next bird count will take place in April during Earth Day celebrations at the Wye Marsh along with several other biological surveys.