Purple Martins

Biology (according to Nature Canada) Further information can be found at Nature Canada

The Purple Martin (Progne subis) is the largest species of swallow in North America. Purple Martins breed throughout North America and make an incredible migration to the Amazon basin of Brazil for the winter.

The Purple Martin eats insects. The Purple Martin is part of a group of species called aerial insectivores that feed on flying insects. Other examples include swifts, swallows, fly-catchers, night-jars, and whip-poor-wills. Purple Martins mostly eat larger prey like dragonflies, moths, mayflies, and even butterflies!

Purple Martins are declining: Aerial insectivores (including the Purple Martin) are in serious trouble. They are experiencing widespread population declines, yet the exact cause remains unclear. Many possible culprits have been suggested including environmental threats along their migratory route and at their wintering grounds (deforestation in the Amazon), decrease in food availability, inability to adapt to climate change, nest site competition with invasive species (particularly Starlings and House Sparrows), exposure to pesticides, and industrial development projects.

Purple Martins love humans! West of the Rocky Mountains, Purple Martins nest mainly in natural cavities such as old woodpecker holes. However in the east, they nest almost exclusively in apartment-like nest houses provided by their human ‘landlords’ this tradition of human dependence have been in place for centuries. Purple Martin landlords take care of their birds by maintaining their house and monitoring the nests. They also help provide protection against predators such as squirrels and hawks, and keep martins safe from aggressive intruders such as Starlings and House Sparrows.

There are three subspecies of Purple Martin. The eastern subspecies s. subis is the most widespread and nest in colonies in human-constructed bird houses throughout eastern and mid-western North America. The western subspecies, P. s. arboricola can be found west of the Rocky Mountains in California and British Columbia. They are known for nesting in natural cavities such as abandoned woodpecker holes, but are increasingly making use of nest boxes as a result of a program that began in the 1980’s to recover local populations of the species. The desert southwest of Arizona and Northern Mexico hosts a lesser known subspecies, P. s. Hesperia, that breeds in natural cavities in saguaro cacti and do not tend to form dense colonies.


  • Average size: 7.5 inches long, 15-16 inch wingspan and weigh about 2 ounces.
  • Color: Adult males have dark plumage (black, blue, purple), with dark purple feathers on their head, throat and belly. Adult females are lighter in color, more gray brown and white, but also have purple feathers on their head and back.
  •  Habitat: East of the Rockies, purple martins nest almost entirely in homes provided by people, such as bird houses. Native Americans, particularly Choctaw and Chickasaw, have made homes for the birds for centuries.
  • Diet: Martins are primarily aerial insectivores, which means they eat insects while flying. Contrary to popular belief, martin’s don’t eat many mosquitoes, since they feed higher in the sky and during the day.
  • Nest: Built of pine straw, twigs and mud and lined with green leaves.
  • Eggs: Martins average about 4 to 6 eggs per clutch, which incubate for about 16 days.
  • Migration: Thousands of purple martins migrate annually from Canada to Brazil—a trip which takes about 4 to 6 weeks and covers 5,000-6000 miles each way.

Attracting Martins

Martins checking a new house

How do you get Purple Martins to come & stay at your location?

Many potential landlords think that by just putting up a bird house for martins  that they will actually get them right away. Sometimes people get lucky but today this is not usually the case. Below you will find several suggestions to get you started as well as other management tips from experienced martin landlords. There are usually some important protocols to be followed so give some of these a try. At least you will be able to say that you at least tried them. Variations to the techniques can then be made. Once you have purple martins at your site, it is important that you remember that the species is in decline and conservation of the species at your colony depends on  proper management. Do some research before putting up just any martin house. Sometimes, landlords fail to attract martins to their site since there are very few martins in their part of the province or they are in decline in their area. As a result, it doesn’t hurt to add martin song or decoys to the set up.

Offer Suitable Housing

Since purple martins like to live in colonies, it is best to offer housing with several compartments or single housing in a larger array. These come in wood, plastic, and aluminum. Modifications to these can be made to suit your location.You may wish to use a few round holes to start and then change over to suitable starling resistant holes if they become problematic. Some types are found in the photo below. The critical key to excluding starlings is to maintain the 1 3/16″ hole height so the martin can enter.

Placement of Housing

Housing should be placed at least 20 -40 feet away from trees, buildings, or other structures to avoid any problems with predator intrusion.  If you have a water source nearby, this is a bonus as martins like to be near water. Housing located on bodies of water often fair better than land based housing. Martins will often leave their housing to go to water to drink and bathe and seek out insect life.

 Purple Martin Songs/Decoys

Playing recorded Purple Martin songs particularly early in the morning or throughout the day can  attract Martins to check out your housing, although it may not guarantee they will remain and nest. Having a purple martin decoy placed on your housing will often lure young first year martins to your site. These are the purple martins that usually start new colonies. It is important to cease playing the tape if hawks are in the area as this will attract them to your site if it is played too often or too long during the day.

Keep the Competition Away

Today  Starlings and House Sparrows are the most common problem invasive species around purple martin colonies and will often establish their presence at your housing before the martins take up residence.   Closing up holes in the housing before martins arrive will discourage the invasive species but they will reappear when the martins arrive and cause further problems by  fighting with the martins or by destroying their nest and eggs. The key is to alleviate the  source of the problem. If you have a house with just round entrance holes, you may even wish to have some starling resistant entrances installed on your housing to prevent the starlings from starting to nest. There are several website articles on dealing with these species and encouraging martins to stay.

Start a Nest

When you open up a couple of martin compartments for the martins, make it welcome for the visitors. Introduce some twigs, soy bean straw, wheat straw, cedar chips, or pine needles on the floor of the housing to look like it’s been lived in. They should be cut into martin manageable pieces if the martin wants to do some rearranging. Smear some mud at the front door and on the back walls to design that lived in look and follow Del McKinnon’s suggestions below.

Purple Martin Lures and Attractants

Often potential landlords have followed the necessary steps to get housing ready but still do not get martins. Try the following suggestions and this may assist in getting that first pair. Martins love prebuilt nests, especially the young SY birds, they arrive later in the season, they are rookies at nest building and are also hard pressed for time. So a pre-built nest is very inviting to them. You can greatly increase your chances of getting them to stay and nest at your site with a pre-built nest. Using the dense Styrofoam (blue or pink) as sub floor about 1/2″ to 1″  thick helps to keep the nestlings warm, and also supplies good traction for their feet avoiding leg splaying when they grow . The females often will scratch out their own nest bowl in it themselves. Place a 1/2″ to 1″ thick Styrofoam on the compartment floor (or nest tray floor behind the perch). Then paint the Styrofoam as well as all the sides of the compartment with mud.  Then add a small handful of stubble straw, bean straw, pine straw, cut into 3 inch lengths to the nesting area, it also doesn’t hurt to add a few green leaves to the nest . The nest is now ready and the martins will find it very hard to resist.

If you choose not to use Styrofoam, you can construct/purchase a nest insert for your house and prepare the bedding material similar for the Styrofoam tray. These nesting trays are readily available from supply houses for various house styles. Compress  wheat, bean, or pine straw and add it to the tray to indicate last year’s nesting material. If the straw is difficult to work with, give it a spray of water and it will definitely be more manageable.

Del McKinnon from the Purple Martin Conservancy suggests artificial spotting inside the compartment.  Using a small paint brush or Q-tip – R Trademark and non-toxic craft paint, dab a series of spots similar to young martin droppings in a strip  about 2- 4-1/2 inches  up the wall and entrance to mimic the lived in look. When the martin peeks in and sees the compartment, he will gladly move in because it looks previously used by baby martins. With mud and artificial fecal spotting, you have the real lived in look.

A dawn song tape or CD played in the early morning hours in May and June will be a beacon for returning martins. Duck hunters have used artificial calls for years and the new apps available on phones and tablets are also ways of attracting them when you are close by. The Dawn Song or Chatter cd mimics martins in such a way that the recording of this song will attract any Martin that hears it.

Add a purple martin decoy to a perch, a roof top, or a pole perch and you have the rest of the equation.  Although this is not a guarantee of hosting martins,give it a try and you may be surprised at your success!

Purple Martin Attraction Success



A Novice Approach to Purple Martin Nest Checks

As  the banding season approaches, Rob and I have always been concerned about what we will see when we get to the banding location so I thought that  producing a nest check guide will  provide you with an approach to monitor your colony .

Some Common Myths  About Nest Checks

  • No need to check, martins have been  living in housing at this colony site for years
  • Martins will abandon the nest if you lower the house to check things out
  • Martins can smell, therefore they can tell that you have touched the nest and will not return

Why Do A Nest Check?

  • To see what’s going on in each compartment
  • To record when nest building begins, eggs are laid, or babies will fledge.
  • To see if there are any predators like snakes, squirrels or owls inside the cavities
  • To see if there are any other insects: ants, beetles, wasps in the house

Tools for the Nest Check (Some suggestions)

  • Clipboard with paper and pencil
  • Smart Phone
  • Tablet
  • Tape recorder
  • Digital camera
  • Video Camera
  • Data form
  • Prognosticator and PUMA ID Charts (available from the PMCA)
  • Small auto mirror to view eggs
  • Cups and strings for plugging holes
  • Disposable gloves/dust mask/baseball cap to keep insects out of your hair
  • Nesting material
  • An extra empty gourd/spare nest-tray just in case
  • Extra housing parts
  • Small flashlight
  • Clothes pins for reinforcing Trio door clips
  • Spare netting for snake prevention
  • Long retractable pole with attached retractable cup to return young to nest compartment
  • Large plastic container to carry contents

How to Proceed

  • What to look for
  • When to check
  • How long do you keep the housing down
  • Setting up a schedule
  • Post nest check procedure
  • Special occasion nest checks

What to Look For

Purple martins usually spend much of the morning hours around the house doing their domestic chores like choosing their compartment, attracting a mate, mate guarding, defending a compartment (s), nest building, gathering mud, nest material, leaves, laying eggs, feeding young, preening, or feeding from their bed and breakfast tray if one is provided. Any one of these activities will give you an idea of their progress. ie: Leaves in a nest are a sign that egg laying will begin soon. This might be a good time to start your regular nest checks.

When to Check

I recommend that nest checks be done after the morning activities have been suspended and the weather has warmed up and most of the martins have left to go out feeding. In the early martin season, it’s not uncommon for the entire colony to leave and this is the best time to check nest progress. Use your tablet, voice recorder, pen and paper, and record what you see happening in the house. The Nest Watch data sheet that the PMCA provides allow for various observations but often landlords will keep a diary of their own colony. Electronic data forms are also readily available on the internet. It is recommended that you do  a nest check minimally once a week and more often as the season unfolds. THE PMCA RECOMMENDS EVERY 4 TO 5 DAYS TO DETERMINE WHEN THE FIRST EGG IS LAID AND 5 TO 7 THEREAFTER. If the weather is too cool or too warm  or the martins are stressed will  also influence whether the housing should be lowered.

After the eggs are laid , it is recommended that the housing be lowered cautiously so that the eggs are not abruptly rolled out of their nests by martins exiting their compartments. Sometimes just speaking loudly, or tapping on a compartment before opening the door will avoid a martin flushing into your face. Brooding hens will often sit tight and observe you as you do your nest check. Sometimes, this is the best time to see if a martin is banded or has suffered an injury by over zealous males.

How Long To Keep the Housing Down

There is no exact number of minutes that housing should be lowered. Use Common Sense  when doing a nest check. If you only have 6 pair to monitor, there is no reason to keep the housing down for twenty minutes.  THE AMOUNT OF TIME A HOUSE IS DOWN WILL BE DETERMINED BY THE SIZE OF THE COLONY. If your martins have not begun to lay, you can quickly determine how many nests you have and at what stage  it is developed.  As your martin season continues, egg laying will begin usually at sunrise so it is important to leave the housing alone.

You will see that after the first egg is laid, an egg will be laid each day until the nest clutch is completed. 5-7 days on the average. After that time the hen will be brooding her eggs for a precise number of days until they hatch. If the first egg was laid on June 5th, (clutch of 5 eggs), the chicks will begin hatching on June 21. How do I know? I use a Purple Martin Prognosticator/Baby photo prints. Always determine the first egg laying date.

SOMETIMES TWO OR THREE NEST CHECKS MAY BE MADE AT DIFFERENT TIMES OF THE DAY DIVIDING THE TIME AMONG THE NUMBER OF HOUSES, GOURDS THAT YOU HAVE INSTALLED.   Leaving the housing down more than 20 minutes, only aggravates the martins and causes them  to be alarmed. I’ve seen martins abandon a compartment when the landlord has been too scrupulous and kept the housing down too long. Sub-adult martins are often more easily frightened off than adult martins when it comes to this abuse.

Sometimes you will have to do three or more nest checks to determine each of the colony’s inhabitants first egg laying day. Hatching days will also be determined by weather conditions and may vary by 5-10 days. Eggs usually hatch in fifteen days and chicks normally fledge between 28 to 32 days. Do not check compartments that contain nestlings that you know are 22 days or older. You can plug these holes with a Styrofoam cup plug with a string and remove them once the housing is raised. Wait about ten minutes before removing the plugs.

Set up a Schedule

Our daily chores and family commitments often interfere with Nest Checks, so I often recommend taking out your Nest Data sheet and determining each day that you will conduct a nest check. You will be on schedule, and any missed day can be quickly made up the day after.

Post Nest Check Procedure

  • Ensure that all door plugs are removed
  • Install the safety pin on your pole
  • Attach the predator/snake guard
  • Lock your system to maintain site security
  • Finally, ensure that all owl guards, if installed have been redeployed properly.
  • Do a walk around to ensure that no chicks have decided to fly out after you have completed your nest check
  • Step back and observe as the martins return to their regular daily routines

Special Occasion Nest Checks (When you should check!)

  • When you notice martin feathers or other accipiter (Hawk) feathers around the colony
  • When your house  doors are ajar or the martins can’t enter their compartment
  • When a chick is out on the porch and can’t get back or you see  the housing  crawling with insects
  • When you find  broken eggs or martin body parts on the ground
  • When a competitive species is lurking about or going in and out : sparrow, starling, tree swallow, bluebird
  • After inclement weather: a cool spell, heavy rain or very windy conditions

The PMCA Market Place has the Prognosticator and the Baby Photo Laminated Plates for sale on  their website. The Martin Watch data forms are also free for downloading. Check out the PMCA article onhow to use a prognosticator as well as baby photo laminated sheets.