Purple Martin FAQ

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General martin questions

Why should I care about martins?

East of the Rocky Mountains, purple martins are now dependent on humans to provide housing for them, and they would probably go extinct without human
intervention. This is due to a tradition shift that began before European settlers arrived in North America as well as competition from invasive species and lack of natural nest cavities in suitable locations. The introduction of English House Sparrows and European starlings in the 1800s affected many of our native cavity nesters. Widespread logging and deforestation removed many of the natural cavities they used generations ago. Land that was once farmland with gourd racks or a martin house has been converted to suburbs in many areas. Martins need us to make sure their housing we provide for them is in good repair, free of mites and other parasites, protected from predators, dry in rainstorms, and properly ventilated when it’s hot outside. If we don’t take care of their housing, they will not have a healthy place to raise their young. Scientists estimate that their population has decreased by 25% since the 1970s and continues to decline in many areas. Purple martins have been enthralling us for generations. Let’s do what we can to conserve their population and preserve the hobby for future generations.

Uh oh, I found a baby martin on the ground, or an injured adult martin on the ground. What do I do?

Unlike many other songbirds, it is not normal to find a martin nestling or fledgling on the ground. When martins fledge, they should be able to fly directly out of the housing, high in the sky with their parents. They should not be hopping around on the ground. Nestlings need to be at least 26 days old and around 50 grams in weight to fledge successfully. If you find a nestling martin on the ground, the best thing to do is to put it back in its own nest as soon as possible. If you are not sure which nest it came out of, put it in with nestlings that look to be at the same stage of development as that nestling. If this is not possible, and there are no other nearby martin colonies that can foster it, then contact a rehabber. A list of licensed wildlife rehabbers is found on our links page. Injured adults should go straight to a rehabber as well.

What is a 'jumper'?

A jumper is a nestling purple martin that has been found on the ground, not yet capable of flight. Nestlings can jump for various reasons: Mite infestations, overheating, starvation, wet nests, or being pushed out of the nest. Always put a jumper back in its nest if possible. 

When can I take my martin housing down for the season for cleanouts?

The end of August is a good time to think about taking housing down for cleanouts and making any necessary repairs or upgrades before next season. By this time, fledging is complete and most martins have left NC (with the exception of some coastal areas, which still may see martins passing through as late as Labor Day weekend).

When should I put up my martin housing for the season?

This depends on whether or not you have an established site. If you hosted martins in previous years, you should have their housing ready by the middle of February. However, specific arrival dates vary by location. Before your martins come back, make sure to keep all other bird species out of the martin housing. If you are trying to start a new colony, late March and early April is a good time to start trying to attract ASYs with no site fidelity or SYs for their first nesting season. 

I have seen a lot of strange abbreviations on martin sites. What do the terms ASY, SY, HY, SY-M, SY-F, HOSP, and EUST mean?

ASY= After Second Year, refers to adult martins at least 2 years of age with their adult coloration.
SY= Second year, subadult/subbie martins. These birds do NOT have adult coloration and are 1 year old.
HY= Hatch year martins, aka fledglings
SY-M= subadult male
SY-F= subadult female
HOSP= house sparrow
EUST= starling

Can you come out and band my purple martins? Can I band my own martins?

Banding migratory birds requires a federal permit and is a long and complicated process. We currently work with 1 federally-licensed bander who bands at two sites in Raleigh. Unfortunately, the bander is not able to take on any more project sites at this time. If you see a purple martin in NC with a red color band on one leg and a silver federal aluminum band on the other leg, it may be one of the martins banded in Raleigh, and we'd like to hear from you! Let us know where you saw it, and if you have a good pair of binoculars, see if you can get the numbers off the band as well. If not, that's ok. We still appreciate hearing about sightings of banded martins!

NCPMS questions

NCPMS General Info: I'd like to be involved in the in-person meetings you have, or the online Zoom teaching topic presentations. Where can I find out more information about them? How can I attend?

If you join as a member, you will find out about these events on our mailing list or in our Facebook group. We also post events on our Google calendar. If you'd like more specific meeting information, please contact us using the email address linked here.

Do you offer martin presentations or can you be a speaker at our next meeting?

NCPMS can do presentations either in-person (within a reasonable driving distance) or over Zoom. Please send us an email to inquire.

Purple Martin Attraction

Why do I still not have a martin colony? I’ve been trying for years now.

The most common reason why folks can’t get a colony established is if the housing is put up in the wrong place: too close to trees or tall shrubs, in a valley surrounded by trees, or in another place with no open flyways. Sometimes if the local martin population is low, it can take a long time to get a colony going. Keep an eye out for paper wasps in unoccupied martin housing. If they are allowed to set up shop, martins will not nest there. Keep all other bird species out of martin housing. If you are allowing bluebirds, tree swallows, or other bird species to nest in your martin housing, they will chase investigating martins away. See the trihabitation protocol here for more info on this scenario.

How can I attract martins to my site? I have a good open location.

There are a few attraction techniques you can try. Play the Dawnsong or Daytime Chatter (available from the PMCA as a cd, or stream Daytime Chatter from Youtube or Erva) at a moderate volume, aimed up at the sky. In some cases, you may find that Dawnsong (vs. Daytime Chatter) produces better results. Try putting up a martin decoy, and smear some mud around the entrance holes to make it look like a martin has nested there before. Add a handful of dry pine needles and small oak leaves to the cavities and pat it flat. The Dawnsong and chatter recordings work best in the mornings, any time from 5am-11am, although it's possible to have martin visitors at other times of the day, too. Once martins start visiting on a daily basis, try turning off the Dawnsong or Chatter recordings and see if the martins will stick around on their own without the recordings.  

Purple Martin Biology

I had martins, but they all left suddenly. What happened?

This depends on the point in the season. If all the martins were there early in the season but left before early June, then the problem was probably predation. It is normal for the martins to leave once their nestlings have fledged. Doing regular nest checks throughout the season will give you the answer.

Will purple martins eat all my mosquitoes?

No. In fact, purple martins eat very few mosquitoes at all, and this fact has been studied and proven by the PMCA. This is due to the height at which a martin feeds (the highest of all swallows) and the time of day that they feed. However, martins WILL eat many other insects, including flying fire ants, Japanese beetles, horseflies, and many other insects. The myth that martins eat mosquitoes was started by a company in the 1950s who wanted to sell lots of martin houses. The sales tactic worked.

It seems like all I see martins eating are dragonflies. Is that their favorite food?

No. Martins are generalists, and will eat several different species of insects. When the nestlings reach the halfway point in development, the adults start bringing in larger insects to give them a bigger meal. This is the point where we may see them bringing in a lot of dragonflies, and that is what is available at that time of year, but they eat lots of other insects as well. In addition, it is likely that the adults do not eat the same diet that they feed their nestlings, but this has not been well-studied. Purple martins spend half their year in Brazil and the surrounding areas and likely have quite a varied diet there as well.

I had martins, but we had a spell of cold, rainy weather and they all died. (Or) My purple martins' nestlings all died after bad weather, or their eggs didn't hatch. What can I do?

Purple martins feed only on flying insects. When the weather is poor (too cold, rainy, windy, or in extreme heat), they may have trouble finding enough food to feed themselves or their nestlings. Females may stop incubating in order to feed themselves. Landlords may provide supplemental food in these cases to help the martins survive. If the martins are present and sitting on the housing, fling crickets towards the colony with a long-handled spoon, and once martins start catching them in the air, you can switch to scrambled eggs (cooked without oils). Alternatively, you can put frozen (and then thawed) crickets on house or gourd porches to feed the martins. It is also possible to train them to feed out of an elevated tray, and this can be very rewarding for the landlord to witness.

Do purple martins nest in Brazil, too?

No. They only nest in North America, and they only raise 1 brood per year in North Carolina, unless their first brood fails. This is why it’s important that they ‘get it right’ while they are here with us and that we provide them a safe place to nest when they are here.

Why are purple martins nesting on my porch/barn loft?

More than likely, what you’re seeing are not purple martins. Barn swallows are related to martins but are a different species of bird. Check out the Cornell website here about barn swallows.

I am also a beekeeper. Will the martins eat all my bees?

No. There are many landlords that keep bees and martins. The martins may eat a few bees, but most landlords notice no effects on their bee hives. Remember, martins are generalists and do not specialize on bees.

It’s early July, and I’ve noticed my martins seem to be leaving! Is something wrong?

Martins start to head for local roost sites in preparation for their migration south as soon as the young start to fledge from the housing. If it’s still early in the season, the adults will often bring their fledglings back to the nest to roost at night for up to two weeks after fledging. At the end of the season, sometimes the adults will lead the fledglings directly to a local roost site after they fledge.

It looks like two females are trying to build a nest together. What is going on?

This is most likely a subadult pair. Subadult males can look a lot like females at a distance, with just a purple speckle here and there, depending on the individual. If you’re not sure which one is which, listen to their vocalizations. Only the male makes the ‘click’ at the end of his song.

Nest checks

What is a nest check?

A nest check is simply observing what you see in a martin nest and writing it down, every 5-7 days after egg-laying starts. Nest checks enable you to check on the status of your colony: how many pairs you have, how many eggs/nestlings are present, and when you might expect them to fledge. Doing nest checks enables you to catch problems and solve them before they become life-threatening: wing entrapments, capped eggs, underfed nestlings, dead adults or nestlings fouling the nest, mites, wet nests, etc.

Won't the adult birds become spooked if I check their nest and then abandon their eggs or young?

No, this is an old myth. Purple martins are bonded to their nest sites, very tolerant of nest checks, and will come right back to their colony site after you are finished. Nest checks should be quick and efficient. The more regularly that nest checks are performed, the more relaxed the adults and nestlings will be with the process.

Do I have to do nest checks?

No, but if you do not, it becomes much harder to figure out what’s going on in your colony, why your martins have left, the seasonal timing of your colony, where to put jumpers, and how to fix any other potential problems. The PMCA recommends nest checks every 5-7 days after egg-laying starts, and continuing every week at least until the young are 22 days of age. After 22 days of age, there is a risk of premature fledging with nest checks unless precautions are taken. (See plug-and-string nestchecks video). Nest checks will NOT cause the martins to abandon your site, and they will come right back after you are finished. Walk under your martin housing daily to check for evidence of problems on the ground as well as to get the martins used to your presence.

I did a nest check and I found one of these problems: capped eggs, underfed nestlings, dead martins, a snake, mites, or a wasp nest. What do I do?

Capped eggs: This happens when part of a hatched eggshell gets stuck over an unhatched egg. Gently remove the cap from the unhatched egg and replace the unhatched egg back in the nest. Capped eggs will not hatch without removing the cap.
Underfed nestlings: If you encounter a nest where one hatchling is much smaller and less developed than its nestmates, you may wish to consider fostering it to another martin nest with hatchlings of the same size as the 'runt'. If this is not possible, contact a rehabber for assistance.
Dead martins: Remove them from the nest before they attract flies or start to smell.
A snake: If you found a snake in your martin nest, then your predator protection was inadequate. Remove the snake and relocate it away from your poles. Please do not kill it. Snakes are an important part of the ecosystem. See our page on predator guards for more information on preventing snake attacks.
Mites: If the nest is swarming with tiny little moving grey dots, those are nest mites. Excessive numbers of them can cause martin nestlings to jump out or can weaken them.  You can control them with a nest replacement (take out old nest, wipe down gourd or compartment with rubbing alcohol, put in fresh clean pine straw and put nestlings back in on top of pine straw) or  put a  pinch of 5 % Carbaryl  dust under the nest to control them. Mites are more common in high humidity, and damp or wet nests. If the nest is wet (especially on the bottom), replace it, and consider  dry-nest modifications for next year. Make sure house compartments have adequate drainage/ventilation or use nest trays to elevate the nest away from driving rains. Diatomaceous earth is NOT recommended, since it is made of very tiny sharp particles that can be inhaled when nestlings flap their wings and stir up the nest. 
Wasp nest: Often an issue in the beginning or middle of a season. Carefully remove the nest and rub the area with nonstick spray or bar soap to prevent the wasps from returning to that spot. Do not use wasp killing spray inside a martin nest.

I did a nest check and found another type of bird nest in the cavity (not a martin nest). What do I do?

Identify the species that built the nest by close observation. If it is the nest of an English house sparrow or European starling, you may legally remove it at any stage of the nesting cycle, regardless of its contents.  If the nest belongs to a native species such as a bluebird or tree swallow and does NOT contain eggs or nestlings, you can remove it. If the native bird's nest contains eggs or nestlings, you must leave it intact until the nestlings of that species have fledged. For more information on dealing with bluebird or tree swallow interference, see this page

What if I can’t do nest checks? I have a martin house or gourd rack on a fixed pole that cannot be accessed without a tall ladder. How do I take care of my martins?

At the very least, put a predator guard on the pole and use SREH (Starling resistant entrance holes). Trap and remove invasive species (English House Sparrows and European Starlings) with ground or nestbox traps. Consider changing out your housing next year to use a rope and pulley or winch and cable system to make nest checks, management, and cleanouts much easier. You can build your own system or buy one.


Why didn’t my martins come back this year?

If you had a colony in years past but not this year, the most common reason is predation: rat snakes, raccoons, or other ground predators. Owls can also predate a martin colony at night. Oftentimes, rat snakes leave no trace of their former presence other than missing eggs or young. Other reasons for colony abandonment include tree encroachment or housing in disrepair. Sometimes if a better colony site is nearby to yours (less tree encroachment, less predation), and you do not take steps to improve your own housing, the martins will move to another location.

It's the beginning of the season. When should I expect my martins to come back? 

This depends on how old your colony is and where you are located. Generally, martins will return within a week or two of when they arrived the previous year.

Starting a Colony and Site Management

I want to set up a colony. What steps do I take?

What is the most important thing to do for my purple martins?

Protect them from predators and keep out invasive species. Put a predator guard on the pole and use SREH to keep out starlings. Shoot or trap house sparrows; don't allow them to nest with martins. If you can’t do anything else this season, just those two things will help a lot.

What's the best type of martin house or gourd rack to use?

Build or buy a pole system on a rope and pulley or winch and cable system. Stay away from telescoping poles, fixed poles, or tilt poles since they make management more difficult or impossible. If buying gourds or building a martin house, make sure they meet minimum size requirements before you build or purchase them. There are many brands of martin houses and gourds on the market that do meet minimum standards, but there are also plenty out there that do not, so it's important to do your research first. Gourds should be opaque and at least 9 inches in diameter, and house compartments should be 6"x12".

I’ve had the same martin house/gourd rack for many years and I don’t see why I should change anything. My colony looks full and I have martins. Why should I make any changes?

If you already have a system in good repair that allows for easy management, future repairs, and cleanouts via a rope and pulley or winch and cable, then that’s great! However, if you are using a fixed pole system, a telescoping pole system, or a tilt pole system, consider changing it out to make management easier. If for some reason you are unable to take care of the housing one day, you will want a system that your family or friends can handle. Telescoping sections tend to stick together and pinch fingers. Tilt poles or fixed poles can’t be lowered for nest checks when martins are present, and make replacing a fallen nestling very tricky, if the need should arise. In addition, if you aren’t doing any nest checks, it’s hard to determine if your site is really full or not. Sometimes single males will claim a cavity without a mate present, or a male will claim multiple cavities and his mate will pick one in which to lay her eggs. True occupancy is determined by the number of pairs you have, which can be counted by numbers of active nests with eggs or young present. If your martin house is using a 6”x6” cavity size, enlarge them during the off-season to 6”x12”. Small 6”x6” rooms are easy pickings for fish crows, and nestlings are much more likely to be pushed out or to fall out. Gourds should be opaque and at least 9 inches in diameter. Remember, a martin is 7.5” and you need room for 2 adults of this size AND their young, which are nearly the same size as the adults when they fledge!

Can’t I just put up a martin house, leave it up, and let nature take its course? I don’t want to do anything else

This approach may have worked before the introduction of English House Sparrows and European Starlings in the mid-1800s, but no longer. Unmanaged housing that attracts martins at first will gradually lose its martins over time, due to invasive species moving in, or deterioration of living conditions over time. It’s our responsibility to watch over the native birds in our yard that choose to use the housing we put up for them. This means that you need a predator guard, should keep out invasive species, and use quality housing that fits the minimum requirements for martins. Consider doing regular nest checks to ensure healthy living conditions for your colony. Lastly, keep it in good repair. Hosting martins is a rewarding experience, and a healthy colony benefits other martin landlords in the area, too. 

Predators and Nest Competition from Other Species

What is a predator guard and why is it important?

A predator guard is a simple device that keeps raccoons, snakes, and other ground predators from being able to climb your pole and eat your martins and their nestlings. While there are many different styles, the most effective is a stovepipe-shaped baffle, mounted at least 4 feet off the ground. You can also use an electric guard. Snakes and raccoons are found throughout the state of NC. Every martin pole needs a predator guard. Click here to read more about predator guards.

Why do I have to use a predator guard? I never see any snakes or raccoons. I keep my grass mowed short. Can’t I just kill any snake I see? Can I rely on my dog/cats/donkeys/etc to kill snakes in my area?

No, you still need a predator guard. This can be a stovepipe-type guard or an electric guard. Snakes and raccoons often come at night when we are sleeping. Snakes are an important part of the ecosystem and killing them is not only unethical, it’s no guarantee that another one won’t appear later. It’s best to prevent one from gaining access to your pole in the first place and use a predator guard.

I had a predator guard, but a snake or raccoon still ate my martins. What went wrong?

 You may have had the guard mounted too low (less than 4 ft off the ground), or too close to a winch box underneath it, or the guard may have been too small. Guards should be at least 24 inches long (longer is better) and at least 8 inches in diameter and not have any rough protrusions on the outside of them. Cables or ropes should run up the inside of them. When in doubt, mount it high and build (or buy) the biggest one you can get. Wax the outside of the guard, and as a backup method of protection, you can secure a wad of fluffed-out bird netting over the top of the guard to stop any snake that manages to bypass the guard. Just remember that netting is a trap, and you must be willing to monitor it daily and release any snake that gets caught in it. If you do not want to handle any snakes, consider changing your guard type, or install an electric guard. Do not use guy wires to stabilize poles since they are easily climbed by predators, too.

What does SREH mean?

SREH= Starling resistant entrance hole. Pictures are available on this page.

I have always used round holes, and I don’t want to use SREH. The holes look weird and I don’t think martins can fit in those half-moon shapes. What can I do?

SREH are made to exclude starlings, which are classified as non-native, invasive birds that can and will kill martins, throw out their eggs, and kill their nestlings. You need to protect your martins from starlings. If you don’t want to use SREH, you should trap or shoot the starlings. Martins cannot fight off a starling inside their nest. The starling can easily kill a martin and this is why it's important to protect your martins. There are different styles of SREH. It’s important to make sure the porch is mounted no more than 1/4” under the bottom of the crescent or other SREH. This will keep the starling from using its long legs to push its way into the entrance. Sometimes after converting your holes to SREH, martins will peek in and may shimmy halfway in and then back out. This is normal behavior when they are first investigating the change and they will soon go in, provided the SREH is the correct size. If you decide to cut one yourself, pay close attention to the dimensions. 

Do starlings and house sparrows really cause a problem for martins? They seem to cohabitate just fine in my martin house/gourds and they seem to leave each other alone. Why should I start eliminating them now?

This is a common comment from folks that do not do nest checks and are not aware of the danger those species pose. House sparrows and starlings are classified as non-native, invasive species. Both house sparrows and starlings will take over and destroy martin nests. Even if a martin chases a house sparrow or starling away from its nest, the invasive species will typically come right back, which can be when the martin landlord is not looking, and they will do their dirty work when the martins are out feeding. Martins that live in housing infested with house sparrows or starlings often fledge less young per nest, or none at all. You need to decide if your martin housing is going to raise invasive species or the native purple martin. The population of the purple martin has decreased 25% since the 1970s, so what you do at your colony site matters. Still not sure? Watch this teaching video for more information.

Can't I just pull the sparrow nests out? Won't that make them go away? I don't like the idea of killing one bird to help another one.

This 'pulling nest' method is called passive management. It rarely works and often causes more problems. House sparrows are extremely tenacious and will often fly right down to the pulled nest material and put it right back into their chosen cavity. In addition, pulling their nest often makes them even more aggressive towards purple martins (or any other species) trying to nest near them. The best solution is to humanely euthanize the house sparrows, which is legal in NC (and most areas of the country). If they have already built a nest, trap or shoot them first, and then completely remove the house sparrow nest. If you have a high population of house sparrows, it may take a while to clear your property, but they have a relatively small home range and long-term control is possible if the landlord keeps at it all season long. For more information on humane euthanasia for HOSP and EUST, see this page

My martin housing has round holes. What do I do now?

Convert them to SREH. You can use SREH plates, SREH tunnels, or cut one yourself using the guide on this page. It’s important to enlarge compartments on houses using SREH, if your compartments were originally 6”x6”. You can do this by knocking out an adjacent wall on a house to make them 6”x12”.

I have a bluebird, tree swallow, great-crested flycatcher, or other native bird nesting in my martin house or gourd rack. Will this be a problem for the martins?

Yes, this is especially a problem if you do NOT have an established site. Do not allow any other bird species to nest in your martin housing. If a native bird is trying to build a nest in your martin housing, close it off and put up separate housing for the bird in question. If you are having trouble getting tree swallows to accept a bluebird house on its own pole, try hanging a white gourd on a separate pole for them instead. For full directions, see the trihabitation protocol here. If a tree swallow tries to move into a gourd rack that is already partially occupied by martins, hang a separate gourd for them near the gourd rack. Oftentimes, the martins will run them away from the rack, and they will then quickly take to the gourd you have set up for them. Alternatively, you can move their gourd off the rack onto its own pole/shepherd’s hook after they have laid 1 egg in it, and then put up a new gourd in the place where the tree swallow’s gourd was hanging. This procedure is also covered in the trihabitation protocol linked above.

I have a hawk trying to eat my martins, or an owl is attacking them. What can I do?

First of all, be aware that it is illegal to shoot birds of prey, so you must use non-lethal deterrence methods. This includes the use of decoys (rotate daily if possible), a dancing man, clapping two long boards together to make a loud noise, an airhorn, or caging around the housing. Tunnels on gourds will NOT protect martins from owls; the owl simply has to beat the gourd with its wings or grab the gourd and shake it in order to flush the martins into its waiting talons. You can see a video on how to build an effective cage here.

"Please keep us safe!"

Thanks for caring about purple martins!

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