Although we begin the season by putting some nesting material in each box, it is up to the martins to add additional material and form it into their cupped shaped nest. When they are ready to lay their eggs, green leaves are added. Why they add the green leaves is a mystery. At Hammo they tend to add bayberry leaves but other martins add apple, or pear, oak or whatever seems to be available.
Bayberry leaves are highly aromatic and one of the theories is that the leaves help in pest control but the leaves may help reduce the temperature of the nest, the humidity of the nest, or help make the nest bowl easier to clean. If you want to read more about that I've included a link below.
http://www.purplemartin.org/update/Greenleaf.html
All about the eggs - The typical martin nest has between 5-7 eggs, with 5 being the average. Subadult females lay between 3-5 eggs. The eggs are laid early in the morning over the course of several days. A cold spell can interrupt the laying process for a day or two or even limit the number of eggs in a clutch.
The incubation period for the martins is tricky to figure...the timing of the hatch begins the next to the last egg is laid and continues for 14-16 days. During this time the female transfers heat to the egg through the featherless spot on her belly called the "brood patch". This was created when hormones caused the feathers in that area to molt and the blood vessels increase. The female periodically rotates the eggs so that all areas of the eggs benefit from the warmth of this patch. Males will also sit on the eggs, but they do not help with the incubation, just help prevent heat and moisture loss and guard against predation.
Bayberry leaves are highly aromatic and one of the theories is that the leaves help in pest control but the leaves may help reduce the temperature of the nest, the humidity of the nest, or help make the nest bowl easier to clean. If you want to read more about that I've included a link below.
http://www.purplemartin.org/update/Greenleaf.html
All about the eggs - The typical martin nest has between 5-7 eggs, with 5 being the average. Subadult females lay between 3-5 eggs. The eggs are laid early in the morning over the course of several days. A cold spell can interrupt the laying process for a day or two or even limit the number of eggs in a clutch.
The incubation period for the martins is tricky to figure...the timing of the hatch begins the next to the last egg is laid and continues for 14-16 days. During this time the female transfers heat to the egg through the featherless spot on her belly called the "brood patch". This was created when hormones caused the feathers in that area to molt and the blood vessels increase. The female periodically rotates the eggs so that all areas of the eggs benefit from the warmth of this patch. Males will also sit on the eggs, but they do not help with the incubation, just help prevent heat and moisture loss and guard against predation.