Purple Martin colonies update 2020

[Gord]

We had a bumper year of Purple Martins last year at the Chehalis River Estuary in Harrison Mills. We added some boxes in 2018 downstream from the Chehalis Estuary in the Harrison River across from Kilby Provincial Park. The last few fall migrations have really shown the success of the efforts to restore martins to the upper Fraser Valley. At sites just downstream, such as at Island 22, birds, sometimes numbering upwards of 40, have been seen staging for migration.

This year we had some really odd river level patterns with a very late peak and sustained high levels. Martins were observed arriving at the Chehalis Estuary colony on April 19, 2020. The boxes at Kilby may have had some nesting activity last year but for certain at least six of the 12 boxes had nesting pairs in them this year. In middle June, adults were observed feeding young. But late June the river came up again, higher than the supposed peak in late May, and many of the boxes went under the water which was a very sad sight.

Recently we went out in a boat once again generously donated by Morrow Bioscience to check on the boxes. At Kilby I was prepared for the worst and as we got close the lack of any martins around was not encouraging. But when we got closer, adult birds came out of about 6 of the boxes! Interesting. A peek inside provided a thankful sight of full-clutches of eggs or newly hatched chicks! The young that were being fed in mid June must have left the boxes just in time before the water flooded them. These eggs and young are a second nesting.

We went up to the Chehalis Estuary and had a duplicate experience of about 10 active boxes. We peeked inside a couple and saw more eggs and young chicks. There was also a clutch of eggs in a natural cavity below one of the nest boxes. Recently fledged Purple Martins had been noted at the site in late June so these eggs and young were also a second brood.

As we were checking each group of boxes, one seemed to have some dry grass blocking one hole. We went to clean it out to discover it was actually a martin skeleton. The skeleton had a band on it which I reported. I heard back that the bird had been banded in 2015 as a chick in Campbell River on Vancouver Island! It is very interesting how the birds disperse and look for new nesting locations.

Map of where the bird was banded and where we found the skeleton.
Image2 by Gord G, on Flickr


They like to add Willow leaves to their nests. I've read it may be to reduce nest parasites.
Img_6269 by Gord G, on Flickr


Chicks. I sent this to the teacher whose students built the boxes so he can share with the children. How rewarding for them to see their hard work paid off!
Image4 by Gord G, on Flickr


Natural cavity below a nest box
Img_6248 by Gord G, on Flickr


Photo inside of the natural cavity
Img_6246 by Gord G, on Flickr

[nickinthegarden]

Thank you for posting all that interesting information and photos. I had not checked out the nesting boxes at Eagle Point park this year so I was unaware of just how near tragic it could have been. On Sunday morning while at Blackie Spit looking for shorebirds (only Lesser Yellowlegs) At the far end of the spit I was visited by a small flock of Purple Martins that nest there. I think there was some teaching or playing going on as they would land and pick up bits of dried seaweed and let it fly in the wind and some of the others would chase it.

Purple Martin by Nick, on Flickr

[imperialbirders]

Hi Gord
Your find is fascinating. What were the chances of someone finding a band on a small bird. Pretty low I would think. I wonder why the bird did not return to the Campbell River area on its return from the south? Is it common for migratory birds to return to nesting sites that are so far apart? Nature is always full of wonder.
Love Nature

[Gord]

Mike, it seems that the young of Purple Martins often seek out new nesting locations when they return from their migration rather than return to the site they were born. I can see this being nature's way of making sure the species spreads itself out and does not put all its eggs in one basket so to speak. With a colony nesting species, if there was a disaster that happened to a colony (we almost had one at Kilby!), having many other colonies helps to ensure that the species prevails. My observations have not disputed this. The first birds to find and use our new colonies up here were all young birds. It's difficult to tell without having them in the hand if a female is older than a year, but a male in its first year is not the solid blue they get from their second year onwards. All the pairs I saw had young males the first year our nest boxes were used. Following years we started to see all-blue males and of course young males who are likely born from other colonies the year before. The birds also move in flocks from their wintering grounds to breeding grounds. Adult birds returning to their colony might bring along a few young birds from other colonies who are naturally seeking new nesting sites?

Wintering grounds for Purple Martins are in South America far as southern Brazil!

[imperialbirders]

Hi Gord
Thank you for your reply. It makes sense to diversify the genes by mixing between colonies. I find these long migrations most interesting. I am pleased your nesting boxes are so popular. It so nice that the numbers returning seem to be increasing, as so much wildlife habit is being lost here and in South America.
Your photos are great and really help tell the story. I learn so much from following this website

Love Nature

Mike