Purple Martin FAQís
The following Frequently Asked Questions are listed together with brief answers that, in many cases, have links to websites where more complete information may be obtained. It is suggested that you look here before posting your question on the PMCA forum.
Thanks to Jim McIntosh for creating the FAQ section, as well as the other martin landlords who have contributed to it.
1. How do I identify Purple Martins? Purple Martins are sexually dimorphic (meaning the adult male and female have different plumages). Martins also exhibit "delayed plumage maturation", meaning the subadult (SY) birds have different plumage patterns than the adults (ASY). See the following site for descriptions and pictures of Purple Martin plumage Identification: http://www.purplemartin.org/MartinID/martinid.html. To distinguish martins from Tree Swallows, which are commonly mistaken for Purple Martins, go to http://purplemartin.org/forumarchives/archive/TSvsPMnew.htm
2. What are the size and age characteristics of Purple Martins? Adult Purple Martins (Progne subis subis) weigh an average of 1.9 ounces (55 grams); their average length is 7Ĺ inches (19.5 centimeters); and their average wingspan is about 11ľ inches (26.8 centimeters). Average age for martins is 2-5 years, with some living 6-7 years; the oldest martin on record lived to be 13 years and 10 months.
3. What are Purple Martin "scouts" and where can I get arrival information? The term "scout" is a misnomer carried over from earlier times when it was believed that adult martins would migrate back to North America, pick out a nesting site, and then travel back to South America to bring back other martins. "Scouts" actually are just the oldest martins that make the spring migration to their breeding grounds before the younger birds do. Subadult martins generally return to their breeding grounds 4 to 6 weeks after the adults return. A report showing the state-by-state status of returning martins can be found at: PMCA's Scout Arrival Study
4. What do HY, SY and ASY mean? HY means "Hatching Year". These are the new martins born during the current spring and summer; they have not yet made their first migration to South America. SY means "Second Year"; these are the subadult martins that have spent only one winter in South America. ASY stands for "After Second Year" and includes all martins that have spent at least two winters in South America; they molt into their adult plumage during their second winter in South America.
5. What is meant by the term "Site Fidelity"? Purple Martins develop a strong loyalty for the nest site at which they successfully breed. If the colony is well maintained and the martins do not suffer reproductive failure (due to predation or other causes) they will return year after year to the same site. "Site Tenacity" refers to a martinís strong territorial attachment to its nest site and a martinís willingness and ability to defend the area from other nest site competitors.
6. What do Purple Martins eat? Purple Martins are obligate aerial insectivores, which is a fancy way of saying they eat only flying insects, and they take them only on the wing, not off the ground. Martins eat beetles, flies, dragonflies, midges, mayflies, bees, stinkbugs, cicadas, flying ants, damselflies, butterflies, moths, grasshoppers, and wasps. Martins are generalists, and do not specialize in taking just one or two types of insects, to the exclusion of others. Martins drink and bathe while skimming over the surfaces of bodies of water. Purple Martins do not eat huge quantities of mosquitoes, despite what some martin house manufacturers claim (this fraudulent claim is used to market their products). See Update issue 2(3), "The Relationship of Purple Martins to Mosquito Control": http://www.purplemartin.org/update/MosCont.html
7. Does cold weather affect Purple Martins? Purple Martins are adversely affected by weather in which the temperature is constantly below about 48 degrees for three days or there is constant rain for a period longer than three days. The martinís dietary staple, flying insects, do not fly in these conditions, and after the three day period, martins will begin to die from starvation. Cold weather will also lead to "communal roosting" by martins, i.e., many birds will congregate in one nest cavity for warmth. Many martin landlords have successfully used emergency cold weather feeding of crickets to martins. See Update issue 9(4), "Cricket Tossing: A New Emergency Feeding Technique for Purple Martins" http://www.purplemartin.org/update/9(4)crickettoss.html Other Cricket feeding information can be found at: http://purplemartin.org/forumarchives/archive/CricketTossing.htm and http://purplemartin.org/forumarchives/archive/CricketFeed2001.htm
8. How do I attract Purple Martins? Attracting martins is not easy, and it must be done correctly to ensure success. There is much for the novice or "newbie" to learn about the proper types of houses and gourds, their proper location and the proper management of a Purple Martin colony before embarking upon this wonderful hobby. You will do Purple Martins a great disservice by not becoming a knowledgeable, active landlord. Before pursuing your desire to attract martins, read everything on the sites listed at the bottom of this FAQ section. Here is one articles dealing specifically with attracting Purple Martins using the "Social Attraction" technique: http://www.purplemartin.org/update/9(3)social.html There are other articles in the "Attraction Techniques" section of the Forum Archives at http://purplemartin.org/forumarchives/archives.html
9. What type of housing should I use? Minimum standards for Purple Martin housing are available at http://www.purplemartin.org/main/housestandard.html. The type of housing you choose is a factor of your personal preference and what appears to be the most effective in your local area. Housing can be made of wood, plastic or aluminum, and there are numerous models available. There are also several poor quality (and very inexpensive) martin houses and gourds on the market which should be avoided like the plague. The compartments in houses should be a minimum of 6" x 6" x 10". Some commercially available houses must be modified to meet this acceptable standard. An article explaining how to modify houses with small compartments can be found at http://www.purplemartin.org/update/9(3)trio.html Gourds may be either natural or plastic; however, it is best if they have a minimum depth of about 10 inches. Natural gourds may be home grown or purchased, and tend to be preferred by martins, but require quite a bit of preparation and maintenance. An article describing how to add access doors to gourds can be found at http://www.purplemartin.org/update/AccDoor.html One source of martin housing is the Purple Martin Conservation Association (PMCA) online catalog at http://purplemartin.org/shop
10. Why are trees a problem in relation to Purple Martin housing? Trees provide cover for lurking aerial predators like Coopers and Sharp-Shinned Hawks, and martins seem to sense this and avoid settling into tree-encroached housing. Flyway and space requirements are covered in the "house standards" link listed above.
11. Does my housing need to be next to a lake or pond? Martins need a daily supply of water to drink and bathe in, and they use lakes, ponds, rivers, and swamps for this purpose. Housing adjacent to a lake or pond is an advantage in attracting them, but is not necessary, as martins will fly several miles to reach such bodies of water.
12. Will Purple Martins bother my neighborís swimming pool? Martins have been reported to drink/bathe in swimming pools. Additionally, although rare, martins may drop their fecal sacs in pools; this behavior is believed to occur as an attempt by martins to mask the odor of the fecal sacs from predators. [Fecal sacs are the nestlingís feces, which martin parents routinely remove from the nest.]
13. Will constant security lighting such as streetlights bother my martins? No, martins are not bothered at all by all-night lighting.
14. Why do I have to worry about starlings and sparrows? European Starlings and English House Sparrows are non-native, aggressive nest-site competitors that have a detrimental effect on all native cavity-nesting birds. Starlings will kill adult martins, their young and eggs if they gain access into the nesting cavity. Sparrows will beak-peck martin eggs (poke holes in them) during the martinís absence, and are known to build their trashy nests over martin eggs and their nestlings (which will soon starve). Neither of these exotic birds is protected by federal or state laws, so it is legal to kill them. Starlings and sparrows must be removed by trapping and euthanasia or by shooting (if legal in your area). Nest tear- out can be used to discourage sparrows, but this is an ongoing, almost fruitless effort, and if done after sparrow eggs have been laid, will likely produce a vengeful reaction of the sparrows toward martins. Starlings and House Sparrows will sometimes throw the martin eggs out of the nest, often puncturing them in the process. This is why landlords occasionally find martin eggs that appear to have been rolled out of the nest onto the porch of a martin house, or on the ground beneath the house. Starling Resistant Entrance Holes must be used on all martin housing to keep the treacherous starling from getting into a martin cavity. A Purple Martin is no match for the vicious beak and power of a starling in the confines of a nest cavity! Information on starling resistant entrance holes can be found at http://purplemartin.org/forumarchives/archives.html
15. How do I trap starlings and sparrows? There are several commercial traps available including the Repeating Bait Trap, Nest Box Trap, and Wire Sparrow Trap available from the PMCA at http://purplemartin.org/shop/index.php?cPath=29 Nest box traps that can be made by the home craftsman include the Troyer S&S Controller (plans available from PMCA), Glenn Davisí NB-Compact Trap: see "Traps" under http://purplemartin.org/forumarchives/archives.html Additionally, there are "insert traps" (trap doors) that can be placed inside various compartments or gourds (also available from the PMCA) that catch sparrows or starlings when they enter the nest cavity.
16. What is the best way to kill trapped starlings and sparrows? There are numerous methods to kill starlings and sparrows that have been trapped. However, the most humane method is by euthanizing them (putting them to sleep) using the ether contained in Engine Starting Fluid (available from most auto stores). The technique for this can be found at http://purplemartin.org/forumarchives/archive/Humane.htm
17. What does SREH mean? SREH stands for Starling Resistant Entrance Hole. These modified entrance holes are rapidly becoming the standard in both houses and gourds. The most popular one is a crescent-shaped hole. They do not completely exclude starlings, but 99% of the time starlings are unable to enter them. There is also an "excluder" type of entrance hole being used by some martin landlords. Information on starling resistant entrance holes can be found at http://purplemartin.org/forumarchives/archives.html
18. What are "excluder" entrances? Excluder entrances were designed by Duke Snyder to completely exclude starlings from entering Purple Martin houses. They are "bat-shaped" entrances and have been successfully used on porched housing, but have not proven successful on porchless housing. See Purple Martin Update 10(1): 8-10, "A Revolutionary New Entrance Hole Design: Duke Snyder's Starling Excluder". Retrofit excluder entrances can be purchased for Trio martin houses from the PMCA online catalog.
19. Why are predator guards necessary? Several predators can easily climb the poles supporting houses or gourd racks and will then make a quick meal of martin eggs, nestlings, and adults. Predators include raccoons, opossums, rat snakes, and squirrels. A properly designed and placed predator guard will keep these predators from climbing a martin pole. Simple greasing of the pole will not deter these predators. See Purple Martin Update issue 8(2), June 1998, "Predator Baffles: Easy, Inexpensive and Effective" for instructions on how to make your own predator guard http://www.purplemartin.org/update/PredBaff.html Predators such as rat snakes, raccoons, and opossums are very common and can be found in city parks, suburban neighborhoods, and in many folkís yards. Most of these predators are active at night, so landlords are often oblivious to their presence. Many folks believe that their clean yards have no snakes. Wrong, particularly in the Deep South. So ALL houses should be equipped with land predator guards. Information on predator guards (including photos) can be found under the "Predators and Predator Control" section of the Forum Archives at http://purplemartin.org/forumarchives/archives.html
20. Do I need to be concerned about aerial predators? There are several aerial predators that prey on martins, including owls, accipiter hawks, falcons, and crows. Owls find martin colonies by hearing the martins vocalizing and making other noises at night in their nests. Owl guards must be placed on houses and gourds to keep owls from spooking martins from their nests or from actually reaching inside and grabbing a martin. There is not much that can be done to deter accipiters (Cooperís hawks and Sharp-shinned hawks) or falcons (Peregrine Falcons and Merlins) from raiding a Purple Martin colony, but properly placed housing with at least 100í of clearance in all directions will usually allow the martins to see these predators in time to escape. Information on constructing aerial predator guards (including photos) can be found under the "Predators and Predator Control" section of the Forum Archives at http://purplemartin.org/forumarchives/archives.html
21. Why are "nest checks" important and how often should I conduct
them? Landlords should lower
their housing or gourd racks frequently (every 5-7 days) to examine the interior
of the cavities [Note: if your housing/gourds canít be lowered, this must be
remedied before martins arrive, or at the very least, prior to the next season]. The primary reason for checking nests is to monitor the welfare of the
nestlings. Steps can be taken to correct problems that would otherwise lead
to breeding failure and possible colony site abandonment. Blood-sucking
nest parasites (harmless to humans) are very common and can become a
problem if they appear in large numbers. Blow fly larvae can weaken or
kill nestlings. Nest mites or fleas can become so numerous as to cause
nestlings to jump from the nest before they can fly. For
more information on nest parasites, see
http://www.purplemartin.org/update/Parasites.html (The first time you see
a parasite-infested martin nests, you will become an instant convert to doing
nest replacements! See the next FAQ).
22. How should I get rid of nest parasites? When a landlord discovers parasites in a martin nest, a complete nest replacement is the safest way to get rid of the parasites. Instructions for doing nest replacements may be found in Update issue 9(2), "How and Why to Do Nest Replacements for Purple Martins": http://www.purplemartin.org/update/92nestrep.html Some landlords put the pesticide Sevin in their martin nests, but this practice conflicts with the recommendations of the manufacturer of this pesticide, and is not recommended by the PMCA. For more, see The Sevin Debate: Intro Pro-Sevin  vs. Anti-Sevin
23. When and how should I do nest replacements? Nest replacements should be done when nestlings are 10 days old and 20 days old, and are ideally done in the afternoon when the adults are away foraging. Basically, the nestlings are removed and placed in a covered, ventilated container containing cedar shavings. The old nest is removed and placed in a plastic Ziploc bag for disposal (do not put old nests in your compost bin). Swab out the interior of the gourd or compartment with isopropyl alcohol (rubbing alcohol) and put in a 1-2" bed of soft, dried, pine needles (White Pine or Pitch Pine) or cedar shavings. Replace the young martins in the nest and plug the entrance hole with a Styrofoam cup or other device that has a long string attached to it. After the house or gourd rack has been raised and the nestlings have had time to settle down for a minute, the plug may be pulled loose from the entrance hole with the attached string. See Update issue 9(2), "How & Why to Do Nest Replacements for Purple Martins" http://www.purplemartin.org/update/92nestrep.html Landlords need to exercise caution when conducting nest checks on martin housing containing older nestlings (22+ days old) because of the threat of premature fledging. For information on how to conduct nest checks with older nestlings, go to http://purplemartin.org/forumarchives/archive/Nestcheckold.htm
24. Why did I fail to attract Purple Martins? There are many reasons martins are not attracted to a house or rack of gourds. See "Ten Reasons Why people Fail to Attract Purple Martins" http://www.purplemartin.org/main/topten.html.
25. Why did my Purple Martins fail to return this year? There are many reasons martins will abandon a previously established colony. See "Twelve Reasons Why People Lose their Purple Martins" http://www.purplemartin.org/main/toptwelve.html.
26. Why donít visiting martins stay at my colony at the beginning of the season? There is no real answer for this. Martins may stop at a site to rest during migration, and even spend the night before continuing their migration. Martins from an established neighboring site might just be curious about the "new" site and want to check it out. Remember, these are wild birds, and the motives behind their various behaviors are not well understood, if at all. If you have a lot of visiting martins over a long period of time, but none stay to nest, check out the "Top 10 Reasons People Fail to Attract Purple Martins" at http://www.purplemartin.org/main/topten.html
27. What precautions should I take if strong winds are forecast? Prevention is the keyword here; be sure the poles supporting your houses or gourd racks are of sufficient strength to withstand heavy winds. However, if you are worried about impending winds, the house or gourd rack may be lowered. CAUTION: do this before the martins have returned for the evening; never lower housing after dark when the martins have settled in for the night. An additional caution is to be certain that the house or gourd rack is prevented from twisting in the wind from its normal compass orientation; this will cause the martins to become disoriented and may lead to nest abandonment. Lowered housing on round poles should be secured with duct tape so that it cannot spin.
28. Will Purple Martins be a problem for beekeepers? Purple Martins may take an occasional honeybee, but they do not specialize on any type of insect and pose no threat to the viability of nearby hives. The kingbird will sometimes prey on honeybees and folks may confuse the kingbird with martins. Kingbirds are also known as "bee martins".
29. Will Tree Swallows compete with Purple Martins? The answer is "No" if you have an established Purple Martin colony. However, if your martin colony is new, or the martins failed to successfully fledge young the previous year, the answer is an emphatic "Yes", and you need to visit the following site for instructions on how to deal with this critical problem: http://www.drugfreeworkplace.com/~Dan/TRIHABITATION/TSEMERGENCY.html
30.Will Bluebirds compete with Purple Martins? As in the case with Tree Swallows, Bluebirds will not be a problem at established Purple Martin colonies. However, if your martin colony is new, or the martins failed to successfully fledge young the previous year, the answer is "Yes". If bluebirds are attempting to nest in a martin house or gourd, close the martin housing and erect a bluebird nest box about 50 feet away from your martin housing. Once the bluebirds have begun nesting in their nest box, the martin housing may be reopened.
31. What should I do when I find a young nestling on the ground? If you have kept reliable nest records, you should be able to determine which nest the premature fledgling or "fall out" came from, and you can put it back in itís own nest. Never put an older nestling in a nest with younger birds, or a young nestling in a nest with older birds. It is also not prudent to place a nestling, even though of equal age, in a nest with 3 or 4 other nestlings; the parents may be subadults and not capable of feeding the extra mouth. Place the premature fledgling on a centrally located, raised and protected platform. The main thing is to get the nestling up off of the ground -- the roof or a shed or garage, at least. Parents will often continue to feed them if this is done. See also Update issue 6(3), December 1995, "Monitoring Tips: Preventing Premature Fledging" http://www.purplemartin.org/update/63PrematureFledg.html
32. What should I do if I find an injured Purple Martin? There are definite "Doís" and "Dont's" regarding injured Purple Martins. Read and follow the instructions provided in the document, "Tending to Sick, Injured, or Orphaned Purple Martins" available at the PMCA Download Center on their home page http://www.purplemartin.org/main/rehab.html Even though your intentions are good, it is technically illegal to possess a Purple Martin nestling or adult, and you should contact your state wildlife agency to get the phone numbers of licensed wildlife rehabilitators in your county. They are specially trained to care for injured wildlife.
33. Why do martins fight so much? I have only one or two pairs and they chase away the other martins. Male purple martins often defend several adjacent nest cavities to reduce competition for available females and to provide potential mates with a variety of nest sites to select from.
34. How high should I place my martin house? Martin houses/gourds can be placed anywhere from 10 to 20 feet in height, with 12 to 14 feet a good range. If there are trees nearby, then the higher height is better and gives the martins easier access to their house.
35. How long does it take for martin eggs to hatch? On average, martin eggs hatch in about 16 days. However, eggs may sometimes take an additional week or more to hatch because of foul weather, which causes the female to suspend incubation intermittently.
36. How long do baby martins stay in the nest before they are ready to fly? Martins stay in the nest on average from 26 to 32 days. The parents will often bring their recently fledged young back to roost in their nests for at least a few days, and sometimes for as long as 2 weeks..
37. I want to have my birds banded. How can I do this? Banding of Purple Martins requires both federal and state permits, since improperly applied or incorrectly sized bands can cause injury or death. Bands are distributed to licensed banders and indexed by the United States Geological Survey's Bird Banding Laboratory in Laurel, MD. Most people who want their birds banded simply want to see how many fledglings return to their colony site the following season, but research has already determined that approximately 10-20% of fledglings return to their natal colony sites as subadults. Most disperse to avoid inbreeding. For more information about bird banding, go to http://www.pwrc.usgs.gov/bbl/
38. When should I open the entrance holes on my martin housing if I am trying to attract Purple Martins? There are two schools of thought on this subject. (1) Open the housing when adult Purple Martins are due back in the area (Click on: http://purplemartin.org/forumarchives/archive/ScoutMap.htm) or, (2) Wait until the subadults are due to arrive in the area. Subadult arrival lags behind adult arrival by 4-6 weeks in the northern 1/3rd of the continent, 6-8 weeks in the middle 1/3rd of the continent, and 8-10 weeks in the southern 1/3rd of the continent. Most new colony sites are started by SY (subadult) birds, since adults return to the same colony site where they bred the previous season. However, adults can sometimes be attracted to new sites under certain circumstances. Read http://purplemartin.org/forumarchives/archive/WhenOpen.htm for a more thorough explanation of this subject. Whatever you decide, be prepared to rigorously control Starlings and House Sparrows whenever you open your housing. If you are not willing to control starlings and House Sparrows, please do not erect housing for Purple Martins because you will only end up breeding their biggest enemies.
39. Why aren't my martins back (yet)? Every year folks get all worried because their birds are either "late" or their numbers are down on any particular date, compared to previous years. However, our scout-arrival database shows that scout dates for most locations have varied by as much as 30+ days over the past 100 years. So, when you look at the 100-year record, there's no cause for concern. Be patient. Variation in the time of arrival is related to weather, age of birds, food supplies, population levels, molt phase, physical condition of the migrant, conditions on the wintering grounds, moon phase (possibly), etc. Total population numbers also go up and down each year. Weather, food supplies, parasites, predators, competition, poisons in the environment, diseases, human persecution, and collisions with manmade objects, all take their toll. However, at this particular date we don't know if migration is 10% complete or 50% complete at any given southern latitude. Therefore, it's way premature to be making judgments on population levels, I feel. The subadults aren't even back yet. If it turns out that population levels are down this year, it would most likely be because of poor over-winter survival in Brazil, likely weather related. However, we have no widespread reports of martin numbers being down in the US this year. We always get more reports of numbers being up, than we do of numbers being down. Bottom line, wait till migration is clearly 100% complete (usually June 1st) to make final population judgments. The Breeding Bird Survey http://www.mbr-pwrc.usgs.gov/cgi-bin/atlasa00.pl?06110 shows martin numbers on the increase, continent-wide. However, there are regional exceptions (Click on the state links). Numbers in Florida are on the decline. Why? Could it be drought (weather), increase in predator numbers, loss of habitat, loss of well-managed breeding sites, or pesticides reducing insect prey? Any or all of these could be responsible. All the more reason for folks in these areas to redouble their efforts to help martins, locally. Hope this will reduce some of the anxiety all landlords experience this time of year. It's too early to be worried about what the final numbers will be this year.
Additional information on Purple Martins can be found at the following sites:
PMCA Download Center: http://www.purplemartin.org
PMCA Update Magazine Articles: http://www.purplemartin.org/update/Reprints.html
PMCA Forum Archives: http://purplemartin.org/forumarchives/archives.html (Articles on subjects such as Management, Housing Improvement, Predator Guards, Nest site Competitors, Attraction Techniques, Traps, etc...are listed categorically)
Here are several more subject-specific articles on martins and martin management:
How to Modify Trio aluminum houses to have 6"x12" cavities: http://www.purplemartin.org/update/9(3)trio.html (Martins prefer the deeper compartments and breed more successfully in them.)
How to Determine the Sex and Age of Purple Martins: http://www.purplemartin.org/update/ColorGuide.html
The PMCA's best Martin Management Tips: http://www.purplemartin.org/update/Management.html
Predator Baffles: How to make them or Where to buy them: http://www.purplemartin.org/update/PredBaff.html