Monitoring Marsh Wrens in Cootes Paradise - 21 June 2024

[David Moffatt]

In 2020 I surveyed Marsh Wren territories in Cootes Paradise by canoe on four mornings during the breeding season.  At the time I was able to identify 8 clusters (loose colonies) of singing males, with a daily maximum of 37 and a cumulative minimum of 42 territories. Yesterday I repeated my route (13 km starting at 5:05 a.m.), and found 44 different singing males, and one non-singing bird carrying a fecal sack.

Cootes Paradise is clearly a very significant habitat for this species. It appears that Marsh Wren populations are stable or slightly increasing. Equally interesting was the fact that the geography of the population has changed. While the densest concentration of territories remains in the area around McMaster Landing and West Pond, where Wrens have been nesting for decades in established cattail marsh, newly restored cattail marshes are maturing and are now attracting Marsh Wrens. The area south of and parallel to the Desjardin Canal and around Rat Island had many more birds than they did in 2020. The latter is directly opposite the viewing tower on the Marsh Boardwalk, so Marsh Wrens should be much easier to detect from a land base than they have been for years.

Other good news from yesterday included a singing Least Bittern east of Rat Island, and a healthy population of Wood Ducks. I counted a minimum of 14 adult WODU, at least five of them females doing distraction displays as they do when trying to attract attention away from flightless young. Whatever young they were protecting were in cattail stands too dense to see through.

Congratulations to all at the RBG and the volunteers who have done so much restoration work on the Marsh, despite repetitive setbacks, over the past couple of decades!

Dave Moffatt