Nest replacement schedule and blow flies

[Ed Svetich-WI]

I have hosted a martin colony for over 20 years in Central Wisconsin. Coming from a scientific background, I make frequent observations and keep copious records regarding my colonies ups and downs. I have reduced my colony to 12 commercial gourds and have 100% occupancy every year. I am down from 30 cavities and and do not advocate large colonies due to management challenges.

As challenging as it was for me to attract that first martin. I was determined to protect them. This was prior to starling resistant entries. Fortunately, starlings are no longer a threat so I focused on other issues.. As I kept almost daily records, I made tweaks to my colony management constantly. To make a long story short, I adopted nest replacements early. Again, I had a smaller colony of 30 gourds and then 24 but I was determined to not only house martins but to produce as many martins as possible. In the colony data 2012 - 2019, 173 pair fledged 865 young. Since no one can guarantee hatching, I record these metrics: the egg to fledged was 92.38% and actual hatched to fledged was 97.7% . Data from 12 pair in 2023 was 69 eggs laid, 62 eggs hatched with 61 nestling fledging for a success rate of 98%.

As blow flies are the main vermin predating martins here, I began to make nest replacements once during the nesting period. I recorded any blow fly larvae found, and I found concerning numbers. Beginning in 2012, I began intensive nest replacement. After seeing blow fly maggots impacting nestling at about day 8 when nestling were still very vulnerable, I chose to change nests on day 7, day 14 and day 20.Today, I made my ninth colony nest replacement (day 7 with 4 nestlings) and noted a small spot of blood on one naked nestling. I collect the soiled nest material in a wheelbarrow and found a dozen blow fly larvae.

The next scheduled nest replacements will occur on day 14 of the 12 occupied nests. Any blow fly larvae found then will be removed with the now soiled nest. Day 20 ditto. Why does this have value? With a 7 day interval, any new blow fly eggs deposited will have little time to develop and attack the now more robust nestling who may be better able to survive the feeding of the blood sucking larvae. I propose that a naked martin nestling is more vulnerable to losing blood from an unknown number of fly maggots. As the nestling mature, they are less vulnerable.

After communication with a PhD who actually studies blow flies years ago, He suggested that rather than destroying infected nests that I should just use the material for mulch. It seems that even blow flies are predated by small wasps who lay eggs within the blow fly larvae. By allowing the larvae to pupae, these wasps can develop and go on to help keep the blow flies under some control.

As I now manage 12 gourds my schedule requires 36 nest replacements. You may be shaking your head about now. If you would do even one nest replacement on day 7 on each nest in your colony, you may produce more martins because you broke the cycle of blood letting on defenseless nestling. Give it a try. Maximizing the numbers of martins from your colony is one way to help other wanna be martin landlords.

Have a productive martin year.

Ed

[Mstan]

Ed, I appreciate everything you wrote. I enjoy watching and listening to the martins but ultimately the goal is successful fledging to populate the martins. You make a good point how this will benefit other future landlords. Thank you.
Stan

[Jones4381]

I have hosted a martin colony for over 20 years in Central Wisconsin. Coming from a scientific background, I make frequent observations and keep copious records regarding my colonies ups and downs. I have reduced my colony to 12 commercial gourds and have 100% occupancy every year. I am down from 30 cavities and and do not advocate large colonies due to management challenges.

As challenging as it was for me to attract that first martin. I was determined to protect them. This was prior to starling resistant entries. Fortunately, starlings are no longer a threat so I focused on other issues.. As I kept almost daily records, I made tweaks to my colony management constantly. To make a long story short, I adopted nest replacements early. Again, I had a smaller colony of 30 gourds and then 24 but I was determined to not only house martins but to produce as many martins as possible. In the colony data 2012 - 2019, 173 pair fledged 865 young. Since no one can guarantee hatching, I record these metrics: the egg to fledged was 92.38% and actual hatched to fledged was 97.7% . Data from 12 pair in 2023 was 69 eggs laid, 62 eggs hatched with 61 nestling fledging for a success rate of 98%.

As blow flies are the main vermin predating martins here, I began to make nest replacements once during the nesting period. I recorded any blow fly larvae found, and I found concerning numbers. Beginning in 2012, I began intensive nest replacement. After seeing blow fly maggots impacting nestling at about day 8 when nestling were still very vulnerable, I chose to change nests on day 7, day 14 and day 20.Today, I made my ninth colony nest replacement (day 7 with 4 nestlings) and noted a small spot of blood on one naked nestling. I collect the soiled nest material in a wheelbarrow and found a dozen blow fly larvae.

The next scheduled nest replacements will occur on day 14 of the 12 occupied nests. Any blow fly larvae found then will be removed with the now soiled nest. Day 20 ditto. Why does this have value? With a 7 day interval, any new blow fly eggs deposited will have little time to develop and attack the now more robust nestling who may be better able to survive the feeding of the blood sucking larvae. I propose that a naked martin nestling is more vulnerable to losing blood from an unknown number of fly maggots. As the nestling mature, they are less vulnerable.

After communication with a PhD who actually studies blow flies years ago, He suggested that rather than destroying infected nests that I should just use the material for mulch. It seems that even blow flies are predated by small wasps who lay eggs within the blow fly larvae. By allowing the larvae to pupae, these wasps can develop and go on to help keep the blow flies under some control.

As I now manage 12 gourds my schedule requires 36 nest replacements. You may be shaking your head about now. If you would do even one nest replacement on day 7 on each nest in your colony, you may produce more martins because you broke the cycle of blood letting on defenseless nestling. Give it a try. Maximizing the numbers of martins from your colony is one way to help other wanna be martin landlords.

Have a productive martin year.

Ed

Excellent. Do you do nest changes without any blowfly presence as a preventative maintenance schedule or only when you see their presence or markings on the young?

[Ed Svetich-WI]

Sorry for the delayed reply.

I replace all nest materials on day 7,14 and 20 even if I do not see evidence of predation. I am trying to break the life cycle of any vermin in the nest. As I remove the nestlings, it is easy to check for any mysterious wounds. A blood spot needs to be explained. Secondly, the maggots are somewhere in the nest material and rarely on a nestling in my experience. I have actually found a maggot attached only once. I do not know if the feeding takes place at night, but that is my guess. They apparently fall off once they have a blood meal only to again attach for their next meal.

I deposit all of the old nest in my metal wheelbarrow and any present blow fly larvae will be seen wiggling in the detritus. They are a dirty gray color and vary in size from tiny to about the size of a swollen watermelon seed., which shows that the fly continues to lay eggs rather than a one time thing. Can you imagine how much blood it takes to appear like a swollen seed? As you have seen if you do frequent nest checks, a seven day old nestling is naked and essentially a pink fat belly. They are totally susceptible to attack by these blood sucking maggots.

On my first series of nest replacements only one nest had blow fly larvae found. I could have missed some in other nests. If I did, they were still removed by changing the nest. As long as the nestlings are out of the nest, why not change it. It only takes a few minutes per cavity and you don't do all of them on one day. If you have records of hatch days, you know the ages of the nestlings in each cavity.

I hope this answered your question.

Have a productive season

[Jones4381]

Sorry for the delayed reply.

I replace all nest materials on day 7,14 and 20 even if I do not see evidence of predation. I am trying to break the life cycle of any vermin in the nest. As I remove the nestlings, it is easy to check for any mysterious wounds. A blood spot needs to be explained. Secondly, the maggots are somewhere in the nest material and rarely on a nestling in my experience. I have actually found a maggot attached only once. I do not know if the feeding takes place at night, but that is my guess. They apparently fall off once they have a blood meal only to again attach for their next meal.

I deposit all of the old nest in my metal wheelbarrow and any present blow fly larvae will be seen wiggling in the detritus. They are a dirty gray color and vary in size from tiny to about the size of a swollen watermelon seed., which shows that the fly continues to lay eggs rather than a one time thing. Can you imagine how much blood it takes to appear like a swollen seed? As you have seen if you do frequent nest checks, a seven day old nestling is naked and essentially a pink fat belly. They are totally susceptible to attack by these blood sucking maggots.

On my first series of nest replacements only one nest had blow fly larvae found. I could have missed some in other nests. If I did, they were still removed by changing the nest. As long as the nestlings are out of the nest, why not change it. It only takes a few minutes per cavity and you don't do all of them on one day. If you have records of hatch days, you know the ages of the nestlings in each cavity.

I hope this answered your question.

Have a productive season

Thanks Ed and it did. Best wishes on an enjoyable season as well.

[Cloudwalker]

I do nest replacements in Iowa because of mites. I use pine needles. I am interested in knowing what others use and if others do nest replacements for mites. I also wonder what people are using for replacement material. I have never seen blow fly larvae.

[C.C.Martins]

Ed,
A well managed colony to be sure! Thanks God we don't have blow flies here. Understand they attack blue birds as well, imagine folks will do nest changes too.
Tom

[Mstan]

I do nest changes for mites here in Missouri. I also replace nest with pine needles. I started doing nest changes after fledging this year. My colony has remained active.