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1. The Purple Martin house at Windsor Castle Park was built and installed by Virginia Master Naturalist (VMN) volunteers in 2021. Do you know how many Purple Martins could build nests in the house, and whether any Purple Martins are using the house?

The Purple Martin house has 14 cavities.  As of May 2022, it had not been used as a nesting site for Purple Martins.  However, in May of 2021, Eastern Bluebirds built a nest in one of the cavities, so the VMN volunteers put up a Bluebird Nesting Box near the Purple Martin house, and the Bluebirds moved over to use it. In June 2022, several adult Purple Martins were seen flying around the house and one nest was discovered with 3 eggs.  The eggs hatched around June 12. As of July 9, 2002, there were 3 healthy chicks about ready to fledge.  Success!

2. A Bluebird nest is made completely of straw or dried grass.  Do you know what a Purple Martin nest looks like?

A Purple Martin nest is constructed of straw, twigs, and mud, lined with green leaves.

3. Vocalizations are a major form of communication in animals and can range from alarm calls to courtship calls.  Vocalizations develop as the martins grow.  Bird songs are longer, more complex vocalizations that seem like an actual song to the human ear. Bird calls are shorter, usually one or two syllables in length.  Do you know when Purple Martins use songs and when they use calls?

Songs are commonly used during courtship and mating, while calls are commonly used to show alarm or location.  The Purple Martin Conservation Association has identified 7 distinct calls and 4 different songs that can be heard from Purple Martins. Some of the calls are known as “Choo”, “Zwrack”, “Zweet”, and “Hee-Hee”.  The 4 Purple Martin songs are “Croak”, "Chortle”, “Subsongs”, and “Dawnsong”.

4. Purple Martins breed in North America and winter in South America. You will only find Purple Martins in the Americas.  You will not find them in Europe, Asia, or Africa. Do you know when they migrate to South America and to which countries they go?

Purple Martins breed in Virginia during the Spring and Summer. The Purple Martin spends its non-breeding season in one of eleven different South American countries:  Colombia, Venezuela, Ecuador, Peru, Bolivia, Paraguay, Argentina, Brazil, British Guyana, Suriname, and French Guiana, with the majority of Purple Martins wintering over in Brazil.​

5. How many eggs do Purple Martins typically lay?

The female Purple Martin lays one egg per day, generally in the morning, for a total of two to eight pure white eggs.  The average number of eggs per nest is four to six.​

6. Birds incubate their eggs by sitting on the eggs to keep them warm and bring them to hatching. Both male and female Purple Martins may sit on the eggs, but only the female does the incubation. Do you know why?

Only the female can incubate the eggs because they have a brood patch, a featherless area rich in blood vessels that transfers heat to the eggs.  Males may sit on the eggs for short periods of time, but they cannot incubate the eggs.

7. Incubation lasts 15-16 days, although incubation can be delayed due to weather.  Hatching may be spread out over two or three days.  Purple Martins fledge, or leave the nest, once they have acquired the feathers necessary for flight and independent activity.  How long do Purple Martins remain in the nest until they are ready to fledge, or fly away?

The young will fledge between 26-32 days after hatching and can receive care from both parents between one to two weeks after fledging.

8. What type of housing do Purple Martins prefer?

There are two types of birdhouses that purple martins prefer:  single structures with many compartments or individual homes arranged in a cluster. Single structure “apartment” style birdhouses feature multiple entrances leading to adjacent chambers. Clustered arrangements of several individual birdhouses can be placed together to create a compact nesting colony. The most popular style of individual birdhouses for purple martins are hollow gourds.

9. Predation is the preying of one animal on others.  There are predators that attack or plunder Purple Martins nests. Can you name the typical Purple Martin predators?

Purple Martins are vulnerable to aerial predators such as hawks and owls, and ground predators such as raccoons, snakes, and squirrels.

10. Traditionally Purple Martins nested in natural cavities such as old woodpecker holes, on rock ledges, or in dead trees.  However, thousands of years ago, people began providing man-made housing for the Purple Martins in the form of dried, hollow gourds.  Over time, the successful nesting of martins in these man-made homes, paired with the decline of natural cavities, led to a complete behavior shift for nesting within the eastern species. This tradition shift is rare.  Only three North American bird species have undergone a complete tradition shift in nesting behavior.  Can you think of the other two?

The others are Chimney Swifts, who nested only in huge, hollow trees and Barn Swallows, who nested in the mouths of caves or other rocky niches.  Today all three of these species nest only on or in man-made structures.