Back in September 2012 I wrote a blog post here on the pre-migration gathering of Purple Martins at Deer Lake Park.
In Martins Departin’? the birds involved in the “… noisy, energetic, and exuberant convocation in the tree tops along the boardwalk” were almost certainly from the colonies at Maplewood Flats, North Vancouver, and at Rock Point, Port Moody. There were no breeding locations in Burnaby at that time.
Adult female and immature Purple Martins, August, 2012.
But now, almost five years later, I’m delighted to report that Purple Martins are actually breeding here in Burnaby, down at Burnaby Lake on the pilings at the west end of the rowing course. Not only is this a first modern-day record for the City (they likely did breed here historically), but there’s a special bonus involved here too.
The spectacular, province-wide recovery of Purple Martins, described in the earlier post, has been almost entirely due to the use of nestboxes erected by many dedicated volunteers here on the Mainland, and on Vancouver Island. Nearly all these locations have been over salt water, usually on wooden docks and pilings.
For some years now there has been great anticipation that, with the expanding population, martins will nest again over freshwater locations, which they historically did. Bingo! Burnaby Lake is freshwater, and the nesting here is one of only four very recent locations where nesting around freshwater has been confirmed – the others being in the mid-Fraser Valley.
How do we know they are nesting at Burnaby Lake? Well, head down to the Rowing Pavilion and take a look for yourself. With a little patience, every 10 to 15 minutes you’ll see the martins entering the upper-right nestbox on the fourth piling from the left. If all the numbers on the box were were readable, it would be 06 – 24. See the picture below.
Adult male Purple Martin exiting the occupied nestbox
A brief aside: this post is notable for its poor pictures. Unfortunately, the birds are distant, fast moving, and adding an additional murky quality today, was the smoke-filled air. Earlier pictures like the above are a little brighter. Today’s are, well, foggier.
Take your binoculars, and you’ll notice the returning adults are carrying food (mainly dragonflies and other large flying insects) into the nest. Try clicking once on the picture below for a larger view. Look carefully at the bird’s bill to see it’s stuffed with insects.
Male Purple Martin about to enter nestbox with food
Carrying food into the nest is one thing, but are there actually young birds inside? We can’t see them after all. However, a higher level of certainty is provided by the picture below. Here you can see the female departing the nest which a large white blob in her bill which she will very quickly drop into the lake. Like many birds, young Purple Martins’ poop is contained in a white mucous membrane “bag” which enables parents to keep the nest clean.
Female Purple Martin carrying fecal sac from nestbox confirming “someone” pooped inside.
Parents carrying out the fecal sacs suggests the youngsters are older than 8 days. After about 13 to 14 days, the young will defecate at the entrance to the nestbox from where parents carry off the fecal sac. I saw no evidence of fecal sacs at the nestbox entrance during my two visits. I estimate from these observations that the young are between about 10 and 14 days old.
Natural Hazards
After about 28 days the young should be ready to fledge i.e. take their first flight – always a risky time for all young birds as they learn the skills of flying and maneuvering, catching prey and avoiding predators.
An added hazard for these young martins is that there is at least one, and probably a pair of Merlins in the area, probably nesting too. I have seen one on both my visits. The parent martins are very vigilant however. Along with the Barn Swallows, which are quite numerous here, they instantly go into attack mode, calling loudly, and vigorously diving and swooping at the Merlin to drive it out of the area. The male seems to be more aggressive than the female in these interactions.
Distant shot of Merlin. The bird was aggressively chased from this perch by the adult male Purple Martin soon after this photo was taken.
However, Merlins, small falcons, are for their size, powerful bird predators. Often making their captures in mid-air after a high speed chase, they could be a significant threat to an inexperienced young martin taking one of its first flights.
A Long History Finally Rewarded
Joe Sadowski, a founding member of the Burnaby Lake Park Association, trail builder, and nestbox constructor extraordinaire, has been waiting 20 years, he tells me, for the Purple Martins to nest in the nestboxes he was instrumental in putting up at the lake. Along with the Park Association, Roy Teo, and Kiyoshi Takahashi have been monitoring these nest boxes and other Purple Martin nesting colonies for many years.
It’s a credit to all their hard work that we finally have these largest North American Swallows nesting in our midst. Rewarded indeed.
Burnaby Outdoors – birds, nature, parks 