I'm late getting back to answer some of the questions, but my birds, and I, thank you for the interest and kind comments.
I love all wildlife, but I especially enjoy having the Purple Martins in my front yard! They are declining due to fewer and fewer people providing safe, proper housing for them to nest in after their migration from Brazi. A flimsy plastic box is nothing but a death-trap.
First, for anyone interested in learning more about the wonderful native Purple Martins I suggest going to the home page of the Purple Martin Conservation Society (PMCA) and reading each of the six documents in the Download Center. That gives a good overview of the birds and their nesting needs. I've added a link at the end of this post.
Geri B - This is my 13th season of hosting my colony. Each and every season has had a unique set of challenges, heart breaks, and joys.
ELNAN - Thank you for the kind words, and while it may 'read' like a lot of work, it
is a hobby and once properly set up (which
can be a job!) the birds take it from there. I do try to keep meticulous records for the two PM groups I belong to, and I do at least two complete nest changes per gourd during the nesting season. Less mites and dryer nests mean more chicks fledge and fly off to their furtures.
My gourds are 14 feet off the ground. I've never had a squirrel attempt to get to them. They tend to attack birds that nest in trees.
I'm in North Dakota; my pole, rack, and gourds routinely stand up to 30-50 MPH winds. The pole is a 2 and 3/8-inch round pole is set into a ground sleeve that is in turn set into a 42-inch deep, 12-inch wide, concrete filled hole. It's pretty stable, LOL!
The rack fits over the pole and holds the 16 arms that the gourds are wired to. There is a pulley at the top of the pole. A stainless steel cable hooks to the rack, goes up and over the top pulley, then goes down to the bottom of the pole and is attached to a boat winch.
I flip a lever on the winch, turn the handle, and the rack raises or lowers down to where I can open the gourds' lids and check on the young birds.
Tree Swallows and Purple Martins are "cousins." There's an entire protocol on how to manage the two species so the TS don't run off your entire PM colony. I'll post a link to it, too.
As for the gourds, I'm using all man-made gourds this year. There is a combination of Super Gourds and Excluder Vertical gourds, you can Google them for the particulars. They are about 11-12" in diameter, made of heavy UV protected PVC, and are easy to clean and maintain. My birds, and I, do prefer the natural, modified gourds, and I have several, but they are getting re-painted and tweaked this summer so I pulled out all the man-made ones. They weigh a bit over 2-lbs. each.
I make some modifications to them such as adding PVC plumbing elbows for extra ventilation near the top of the gourd; adding 3/8" uplift tubing through the hanging holes so rain does not run down the hanging wire and drip into the nest. I'm in the process of installing PVC tunnels that I buy from a man in SC. These prevent hawks and owls from reaching into the gourds and pulling out the chicks. The birds also love the porches.
I'm rushed for time today, but I'll be back tomorrow to answer the rest of the questions and will hopefully have a new nest check to report.
Toward the bottom of this link is a downloadable wealth of Purple Martin information.
http://www.purplemartin.org/