Recognition Of Young By Parent Purple Martins
The ability of mammals and birds to recognize their young becomes an important life and death issue for mammals that live in herds and for birds that nest in dense, open colonies. These animals must be able to differentiate their babies among the multitude of other young. In mammals, smell, sound and sight become important in recognizing their young from others, particularly in herd/social settings. With birds, sight and sound are paramount as the sense of smell is poorly developed.
Most animals have no biological interest in raising young that are not their own, and adoptions in the wild are indeed rare. Most parents are fully occupied with raising their own young and another mouth to feed is not in the best interest of those parents. In many herd and colonial mammals and birds, orphaned young or young that become separated from their mothers are often doomed. This is particularly evident in such herd mammals as the African wildebeest and in huge seabird colonies. These unfortunate young are not taken care of by the other members of the herd or colony. They wander aimlessly until they are caught by predators, killed by other colony or herd members or die of starvation.
However, some social mammals like African lions and wild dogs (wolves, African hunting dogs) collectively take care of their young. There is a biological interest in these cases as most of the adults are related, and the young, particularly the females, often stay with the family group for life and contribute to the welfare of the other members through hunting and territory defense. Though lionesses recognize their own young, they also take care of all the cubs in the pride. These animals are truly a family and behave accordingly.
In purple martin society, martin colonies are a random aggregate of largely unrelated birds that are nesting together and are not family. Each martin pair and their young are independent of the other colony members. In fact, martins view each other as competitors and fiercely defend their territory. However, this colonial nesting behavior of martins does create an environment where the young of different pairs may commingle under certain conditions.
Since martins nest in cavities and their nests are not in open view of each other, recognition of the young by the parent martins is not as important as that, for example, of seabirds nesting closely together in full view of each other. This is particularly true as long as the baby martins are residing in their enclosed nest cavity and not mixed with other martin babies. The parent martins simply enter the cavity and feed their young; they do not have to search for their young among a multitude of other babies in an open colony. However, this paradigm seems to change when the young martins leave the nest and there are large numbers of baby martins flying about. At this point, recognition of the young by the parents may become an issue.
I have studied purple martins for many years and have often wondered about the ability of parent martins to recognize their young among the multitude of recently fledged babies. This was particularly true at my super purple martin colonies where hundreds of recently fledged baby martins were in the air at one time and being brought back to roost in their nests by their parents.
At what point do parent martins recognize a baby martin as their baby? Or do parent martins even recognize their young? Do parent martins take care of any baby martin other than their own either in the nest or out? Do other parent martins adopt orphaned baby martins that have left the nest in the absence of their parents?
Recognition Of The Young Inside The Nest
Parent martins apparently do not recognize their biological young while they are nest bound. Baby martins of the same size can be mixed from different broods and the parent martins do not differentiate between the young; nor do they recognize different numbers of young. However, differences in the size of young can trigger various responses from parent martins. For example, a large, well-feathered baby martin that has moved into a nest of recently hatched babies is perceived as an intruder and attacked by the parents of the newly hatched young. However, if a baby martin moves into a nest of similar sized young, then the parents will feed it as if it were their own. Size and the stage of physical development are key factors that parent martins respond to while the young are in the nest. The greater the disparity in baby size and development then the greater the chances the parent martins will recognize such a newcomer as not belonging and respond negatively. Even in these cases, the newcomer is often eventually accepted and such acceptance may adversely impact the welfare of the other less developed young. The larger young will consume most of the food.
Recognition Of Young: Either Just Prior To Fledging Or During Their Maiden Flight
So at what point would martin parents possibly recognize a baby martin as their own? This is an important factor for colonial nesting birds where the opportunities for brood mixing are common. For a long time, I believed that parent martins learned to recognize their young via unique vocalizations when the young first left the nest on their maiden flight and that still may be true. However, the parents may learn to recognize their young just prior to fledging via the same vocalization behavior. Why? Sometimes only one parent is there at fledging time, but still both parents must be able to recognize their young after fledging. This infers that the recognition vocalization may be developed just prior to fledging so that each parent will be able to recognize their young even though the father or mother may not have been present during their babies’ maiden flight. Is this time frame just a day or is it several days? That is the question to answer.
When young martins are preparing to fledge, at least one of the parent martins is nearly always there. The parent martins may emit certain vocalizations or initiate unique behaviors that trigger the fledging response. As soon as the baby takes flight, the parents immediately accompany their baby and call to it and the baby calls back to its parents. There is a continuous interchange of vocalizations between the parents and the young. The parent martins stay close to their young, continue to call, and lead the young to a nearby tree, power line, television antenna or even house roof. Often times, the young from a brood are dispersed over a wide area during that initial flight, but the parent martins know where their young are.
Eventually, the parent martins assemble their young at a family assembly site. This family assembly site becomes an important feeding station for the recently fledged young until the young become more independent. It is also possible that young that have become separated from their parents learn to return to this site.
Though the young’s vocalization is probably the key identifier that the parents respond to, it is possible that they also use some kind of sight recognition. Perhaps parent martins are able to differentiate subtle variations in plumage coloring or other physical traits in their babies. Possibly a combination of appearance and vocalizations is used by parent martins to recognize their young when they fledge and distinguish them from others.
Recognition Of Young During Roosting Time
One of the best indicators that martins may recognize their young after they leave the nest is the behavior of parent martins at roosting time. The vast majority of the nesting pairs in my colonies always bring their young back to roost in the nest for a few nights. This colony roosting behavior declines as the young became more independent. In the evenings, there would be well over 100 parent martins and their young returning to roost at my super colonies. The sky would be filled with martins as the parents brought their young back to sleep in their nests. In spite of the apparent chaos and confusion, each parent martin seemed to keep in touch with their own young. Parent martins did not randomly fly to any young bird that was flying around and then guide that baby back to the nest. Parents and young alike were constantly calling, and though we humans cannot discern any difference in calls, it is possible that martins can. Over and over again I would watch a male or female martin ignore numerous flying young and single out a specific baby. The adult martin would call repeatedly to the young and the young would respond and follow the adult. The parents were most likely responding to the young’s unique vocalization and perhaps even their physical appearance.
It is interesting to note that the recognition bond between parent martins and their young is mainly an “outside the nest” phenomenon. When martins bring their young back to roost, many times the fledglings will enter the nests of other martins. There is often considerable commingling of broods at the colony site. Fledglings get mixed up and spread out in various gourds/house compartments. These fledglings are only perceived as “intruders” when they enter the nests of martins with small young and there is a significant size difference. These parent martins will try, but not always succeed, in evicting the larger youngsters.
Young That Leave The Nest In Absence Of Their Parents
What happens to those few baby martins that fledge in the absence of their parents prior to establishment of a recognition vocalization? Will their parents find these babies even though the parents were not there on the babies’ maiden flight? Will other martins adopt these orphans?
Baby martins may fledge in the absence of their parents for several reasons. Unmated subadult (SY) males often enter the nests, viciously attack the young and may force a baby to prematurely leave. Nests that have been overrun with parasites can force youngsters to fledge early and so can hunger or extreme heat. Young may fly out if the landlord lowers the martin house/gourd cluster and triggers a fear response.
From what I observed in my large colonies, these babies are in trouble unless they can somehow manage to return to the colony and enter a nest with similar size young. Many no doubt die of starvation or are killed by predators. I could always identify these orphans as they flew through the colony, calling and searching; they seemed totally lost. There was no parent martin flying with them and protecting them. The unmated SY males that are roving through the colony will hunt these babies down and viciously attack them. These babies are helpless as their fathers are not there to protect them. Other parent martins do not fly to them and bring them back to the nest. In fact, should these orphans approach another nest with one of the parents there, the parent martin will savagely attack and try to drive the newcomer away. Again, it is not in the biological interest of the parents to adopt another non-related mouth to feed. Plus these parent martins have no family relationship with this orphan.
And what about the parents of these young that prematurely fledge prior to the establishment of any recognition vocalization? These young left the nest in the absence of their parents prior to the formation of a recognition vocalization or without that initial outside contact process during their maiden flight. The rightful parents never established the critical recognition vocalization, never saw their young leave nest, did not accompany them on that initial flight, and did not call back and forth to their young. That first important outside the nest bonding that occurs between the parent martin and its young is missing. Since parent martins do not appear to recognize their young in the nest or perhaps do just prior to fledging, then these baby martins may truly be orphans. Other parent martins do not adopt such fledglings and will attack and try to drive them away.
Vocalizations Of The Young May Be The Key Identifier
Recognition of young by parent purple martins is not that important as long as the babies are in the nest. When baby martins fledge, unique vocalizations between them and their parents may be critical in establishing a recognition bond. Vocalizations of the young may be the primary identifier in their recognition by their parents though some kind of physical appearance factor may be evident, too. Parent martins may be able to discern differences in calls made by their fledglings from the calls of others.
Steve Kroenke
Recognition Of Young By Parent Purple Martins
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Steve Kroenke
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Last edited by Steve Kroenke on Tue May 20, 2008 8:40 am, edited 1 time in total.
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Steve Kroenke
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Baby purple martins are hatching now and before you know it they will be fledging. More of the eggs in my colony are hatching. I am re-activating an older posting of mine dealing with the recognition of young by parent purple martins. This article provides some of my thoughts on this subject.
Steve
Steve
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Steve Kroenke
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In many parts of the Deep South martins are feeding young and some have already fledged. Since martins are a colonial species, the parents must learn to recognize their babies at some point and focus on feeding and caring for them among many others. I am re-activating an older posting of mine that deals with the recognition of young by parent martins and provides some of my observations and insights.
Steve
Steve
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Guest
Steve - that was really interesting. Last year I had my first pair, and the male was, I assume, killed before or right after the young hatched, as he never appeared again. The female did a good job of keeping herself and the babies going and they all successfully fledged. I noticed right before they fledged (a number of days) that other martins began hanging around. We hadn't had that before, but now there would be 7-10 martins hanging around, looking in at the babies, making lots of noise. Their actions didn't appear to be aggressive, although being new, I may not have recognized it correctly. When the young fledged, not only was mom around, but several of these others as well. As far as I could see, again, they were not aggressive towards the youngsters, and all successfully fledged and returned a few nights so I could see they were unharmed. I wonder how different it is with a super colony vs. a small (1 pair) colony. I look forward to learning more about these amazing birds!
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Steve Kroenke
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Dick,
Thank you for sharing your observation about the martin babies that fledged in the absence of its parents and were found by them. That event tends to support the idea that martin parents learn to possibly recognize their youngs' vocalizations just prior to fledging.
By observing martins closely as you do, we can learn more about their behavior and biology. You often post many interesting observations about martins and I bet you learn new things every season about them!
Steve
Jbatch,
I am glad you enjoyed the post.
Since you had one family of martins, there were not other established pairs at the colony which may have been aggressive toward the fledglings if they had tried to enter those martins' nests.
The visiting martins tend to vary in their responses to martin fledglings. ASY and SY males tend to attack and, unfortunately, copulate with recent fledglings. I have photos of SY males assaulting and copulating with a martin fledgling. When the fledgling flies, the males will attack its back area. When the fledgling is perched somewhere, the males will mount and copulate with it.
Female martins do not pursue and attack fledglings in the same manner as males. Female martins with nests will attack and try to drive away other fledglings that may try to enter their nests. If you had mainly visiting female martins, then they would not have been that aggressive toward the fledglings.
Yes, there are differences between large and small martin colonies relative to martin behavior! In the super colonies, everything is amplified, both good and bad it seems regarding martin behaivor.
I am glad you had a successful season last year and the mother martin was a great Mom! I have had single females and males successfully raise their families though the females tend to do a better job.
I hope you will continue to study your martins closely. You will be amazed at what you will learn. I learn something new every season it seems.
Good luck this season.
Steve
Thank you for sharing your observation about the martin babies that fledged in the absence of its parents and were found by them. That event tends to support the idea that martin parents learn to possibly recognize their youngs' vocalizations just prior to fledging.
By observing martins closely as you do, we can learn more about their behavior and biology. You often post many interesting observations about martins and I bet you learn new things every season about them!
Steve
Jbatch,
I am glad you enjoyed the post.
Since you had one family of martins, there were not other established pairs at the colony which may have been aggressive toward the fledglings if they had tried to enter those martins' nests.
The visiting martins tend to vary in their responses to martin fledglings. ASY and SY males tend to attack and, unfortunately, copulate with recent fledglings. I have photos of SY males assaulting and copulating with a martin fledgling. When the fledgling flies, the males will attack its back area. When the fledgling is perched somewhere, the males will mount and copulate with it.
Female martins do not pursue and attack fledglings in the same manner as males. Female martins with nests will attack and try to drive away other fledglings that may try to enter their nests. If you had mainly visiting female martins, then they would not have been that aggressive toward the fledglings.
Yes, there are differences between large and small martin colonies relative to martin behavior! In the super colonies, everything is amplified, both good and bad it seems regarding martin behaivor.
I am glad you had a successful season last year and the mother martin was a great Mom! I have had single females and males successfully raise their families though the females tend to do a better job.
I hope you will continue to study your martins closely. You will be amazed at what you will learn. I learn something new every season it seems.
Good luck this season.
Steve
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Guest
Steve,
Saved your article to read this evening. I try to read everything you share. Your articles are very helpful to us newbies.
When the males copulate with the fledgling, does it result in a fertile clutch? Does that mean he pairs with her, or does she miss the migration back to Brazil?
Do any PMs miss the migration?
What happens if a pair claim a cavity before the returnees get there?
Ignorance is not bliss.
Thank you for all you do.
Saved your article to read this evening. I try to read everything you share. Your articles are very helpful to us newbies.
When the males copulate with the fledgling, does it result in a fertile clutch? Does that mean he pairs with her, or does she miss the migration back to Brazil?
Do any PMs miss the migration?
What happens if a pair claim a cavity before the returnees get there?
Ignorance is not bliss.
Thank you for all you do.
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Steve Kroenke
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Hey Liz,
I am glad my writings have been helpful to you.
The male martins copulate with fledglings perhaps to exert some kind of dominance/control over them. No one really knows for sure. You can see somewhat similar behavior in herd mammals such as the African cape buffalo where dominant bulls will mount and simulate copulation with a weaker male. The purpose of the copulation action is not to fertilize, but perhaps is to establish dominance. So in the case of martins there would be no fertilization as the fledglings would not be sexually mature at that time and probably male and female fledglings are attacked. Also, the male martins would not be pairing with the fledglings. It seems the males are making direct attacks on the fledglings and copulation is just one facet of it.
All healthy martins would participate in the migration to their wintering grounds in South America. This behavior is probably genetically determined. Also, martins may respond to daylight levels which gradually diminish as summer progresses and this may trigger biochemical changes in martins to stimulate them into migrating.
There are many fascinating facets of purple martin biology and behavior and much is still a mystery! Maybe some day we will unravel all these mysteries. I hope I live long enough to see the answers!
Steve
I am glad my writings have been helpful to you.
The male martins copulate with fledglings perhaps to exert some kind of dominance/control over them. No one really knows for sure. You can see somewhat similar behavior in herd mammals such as the African cape buffalo where dominant bulls will mount and simulate copulation with a weaker male. The purpose of the copulation action is not to fertilize, but perhaps is to establish dominance. So in the case of martins there would be no fertilization as the fledglings would not be sexually mature at that time and probably male and female fledglings are attacked. Also, the male martins would not be pairing with the fledglings. It seems the males are making direct attacks on the fledglings and copulation is just one facet of it.
All healthy martins would participate in the migration to their wintering grounds in South America. This behavior is probably genetically determined. Also, martins may respond to daylight levels which gradually diminish as summer progresses and this may trigger biochemical changes in martins to stimulate them into migrating.
There are many fascinating facets of purple martin biology and behavior and much is still a mystery! Maybe some day we will unravel all these mysteries. I hope I live long enough to see the answers!
Steve
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Guest
So the young will continue to live with the parents for a week or so after they fledge? Then move on to find their own housing?
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Steve Kroenke
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After martins fledge, they tend to stay with their parents for a short while as they are taught hunting and flying skills. Martins become independent quickly and are catching their own food within a few days to a week. However, the family group probably stays together longer as I have had parent martins bring their young back to roost in my houses for nearly two weeks. But by then, the fledglings are flying well and can catch their own food. The female martins are often more closely bonded to their fledged young and may stay with them longer. So probably the family unit of a typical martin family probably lasts anywhere from over a week to maybe two weeks and by then the young are largely on their own. After that, the independent fledglings may visit various colonies for possible nesting opportunities the next season and still return to roost at their natal site prior to their migration south.
Steve
Steve
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Steve Kroenke
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Soon many martins will be fledging in the Deep South and the parents will have to keep track of all their babies. Martins like other songbirds must be able to recognize their young from others and feed and take care of their babies. Since martins nest in colonies, it is important that parents be able to recognize their young from others so that they can focus their parental duties in raising their genetic offspring and not the young of other martins.
I am re-posting this older article dealing with the recognition of young by parent martins.
Steve
I am re-posting this older article dealing with the recognition of young by parent martins.
Steve
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Littlebit45
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New landlord here...my question is when the young fledge do they not come back to the house they were born in the next year.
Also, I just got martins last week they will still have time to nest and lay eggs this year right?
Thanks
Also, I just got martins last week they will still have time to nest and lay eggs this year right?
Thanks
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Steve Kroenke
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Littlebit,
Banding studies of martins suggest that most fledglings that survive to become SYs the next year disperse to other colony sites rather than to the site where they were born. This minimizes inbreeding and helps to spread the martins around. However, some fledglings may return the next season to their home colony. Martins may disperse several hundred miles from their natal colony though most probably look for closer nest sites.
I didn't see where you are located and your location can be a key factor in determining if martins will follow through and complete the nesting cycle. Probably for most areas in North America if you have martin pairs that bond to your colony in mid-May then the chances are very good they can successfully breed. I have had mid to late May martins successfully breed at my previous martin colonies in north Florida and at my current northwest Louisiana site.
I hope you have a great martin season and raise many babies! Once they successfully breed at your colony and you take care of the martins, your colony will often grow and flourish.
Steve
Banding studies of martins suggest that most fledglings that survive to become SYs the next year disperse to other colony sites rather than to the site where they were born. This minimizes inbreeding and helps to spread the martins around. However, some fledglings may return the next season to their home colony. Martins may disperse several hundred miles from their natal colony though most probably look for closer nest sites.
I didn't see where you are located and your location can be a key factor in determining if martins will follow through and complete the nesting cycle. Probably for most areas in North America if you have martin pairs that bond to your colony in mid-May then the chances are very good they can successfully breed. I have had mid to late May martins successfully breed at my previous martin colonies in north Florida and at my current northwest Louisiana site.
I hope you have a great martin season and raise many babies! Once they successfully breed at your colony and you take care of the martins, your colony will often grow and flourish.
Steve
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Joe Zorn
Hey there, Steve,
I see this is one of your reoccuring posts, but I've never seen it.
I often wonder what happens to babies that get scared out of the nest a day or so before they are scheduled to do so.
I had one nest last year that only had three of six babies make it to fledgling size. Just a day or so before the due date, All three of them took off as I was cranking the house back up. Mom was not around. I was sick! Not a thing I could do, as all three flew to different trees in the neighbors yards.
For a couple of days after that, I would see the mother at the gourd just at dark, watching for the babies I guess., and calling. But they never did return. It was in one of two nest cams I had last year, so I would see her in the nest by herself after dark for about two days, then she too was gone.
Now I plug the entrances with soft styrofoam with a string attached before I crank it back up. Then pull the string after I have the snake guard reattached. None have flown this year.
I guess my most lingering question is how long the babies stay with the parents. Do they head south with them, or are they independant by then?
I see this is one of your reoccuring posts, but I've never seen it.
I often wonder what happens to babies that get scared out of the nest a day or so before they are scheduled to do so.
I had one nest last year that only had three of six babies make it to fledgling size. Just a day or so before the due date, All three of them took off as I was cranking the house back up. Mom was not around. I was sick! Not a thing I could do, as all three flew to different trees in the neighbors yards.
For a couple of days after that, I would see the mother at the gourd just at dark, watching for the babies I guess., and calling. But they never did return. It was in one of two nest cams I had last year, so I would see her in the nest by herself after dark for about two days, then she too was gone.
Now I plug the entrances with soft styrofoam with a string attached before I crank it back up. Then pull the string after I have the snake guard reattached. None have flown this year.
I guess my most lingering question is how long the babies stay with the parents. Do they head south with them, or are they independant by then?
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Steve Kroenke
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Hey Joe,
Martin fledglings become independent rather quickly as martins are birds of the open skies and must develop strong flying skills in short order to survive. I have observed that fledglings are usually catching their own food within a few days of leaving the nest after appropriate care by their parents; this time frame can vary. Martins do require this initial parental care as martins are not like chimney swifts. Chimney swift fledglings leave the nest and are on their own immediately without any parent care.
Martins fledglings may stay with their parents for about a week to ten days after leaving the nest and are probably on their own a short time after that. The martin family is not enduring and dissolves rather quickly. The mother martin appears to be more bonded to the young than the male and she may stay longer with the youngsters. I have had martins bring their young back to roost in my colonies for nearly two weeks in some situations though most bring them back for less time.
By the time martins are heading south, the family units would be dissolved and the young independent. So the hatchlings would not be guided by parent martins during migration.
Steve
Martin fledglings become independent rather quickly as martins are birds of the open skies and must develop strong flying skills in short order to survive. I have observed that fledglings are usually catching their own food within a few days of leaving the nest after appropriate care by their parents; this time frame can vary. Martins do require this initial parental care as martins are not like chimney swifts. Chimney swift fledglings leave the nest and are on their own immediately without any parent care.
Martins fledglings may stay with their parents for about a week to ten days after leaving the nest and are probably on their own a short time after that. The martin family is not enduring and dissolves rather quickly. The mother martin appears to be more bonded to the young than the male and she may stay longer with the youngsters. I have had martins bring their young back to roost in my colonies for nearly two weeks in some situations though most bring them back for less time.
By the time martins are heading south, the family units would be dissolved and the young independent. So the hatchlings would not be guided by parent martins during migration.
Steve