plastic gourds: condensation mystery

[Kelly Applegate~MN]

I was wondering if any landlords out there experience condensation in airtight plastic gourds in the last week before fledge? I have had some problems with airtight plastic gourds accumulating moisture leading to a nasty smell and fermenting wet nests. I used to think that maybe moisture was wicking through the drainage holes into the nest material from underneath, but now I'm thinking that the young are exhaling moisture to the point of making the nest wet. Maybe the solution is to put some PVC elbows to help vent moisture, but it's a touchy game with too much venting here in the north parts........especially before the young are fully feathered. Anyone else notice this?

Also, I'm curious if anyone has had problems with tunnel-type housing trapping fecal matter inside the cavity, leading to young birds wings and tails caked with fecal matter and unable to fly. Last year I had to wash several young after finding them on the grass beneath the housing.

[Steve Kroenke]

Kelly,

Down here in the Deep South, I have had some problems with unventilated plastic gourds that became hot/humid inside to the point where the nests were wet and the nestling martins were nasty looking. This problem was particularly troublesome in some horizontal plastic gourds. I would open the access lid and the hot humid air would rush out! It was almost like a sauna inside! The poor martin nestlings were trapped in a wet hot cavity. The nests were sometimes almost soggy and the nestlings' feathers dirty looking.

The horizontal shape and tunneled entrance area of the unventilated plastic gourd seemed to encourage the build up of heat/humidity because there was no way for it to escape from the back/top. The only opening was the entrance hole which is low down and the nest area was located over a foot away in a narrow cavity where heat/humidity could easily accumulate in the back area and stay there.

After I drilled two ventilation holes (3/8 inch diameter works well) in the upper back of my Troyer Horizontal gourds under the two "bumps" or "canopies" which are there for that purpose, I have not had the humidity problem anymore though heat can still be an issue under extreme conditions. Now the heat/humidity can escape out these vent holes and the chances of a significant build up are minimized.

So using some kind of ventilation for your plastic gourds may help evacuate hot humid air that can build up inside airtight plastic cavities. The PVC elbow approach is a good one and I am sure other vent hole types will work, too such as what I use for my Troyer gourds. I know in your area you are often concerned about cooler weather and perhaps too much venting can create issues inside the martin nests. But down here in the Deep South heat and humidity can be big problems for martin cavities and venting can be a life saver.

Regarding tunnels and fecal matter accumulation...I have seen some feces trapped in the tunnels, but not to the point where the feces had become caked on the martin nestling feathers. So that has not been an issue at my martin colony.

Steve

[Emil Pampell-Tx]

I agree that ventilation is necessary. It helps cool, allows air circulation which helps dry a moist nest, and it gets rid of the stale smelly air. All three of these are much more desirable than a hot wet stinky nest,

That is one reason why the S&K gourds are my favorite. They have the ventilation thru the top of the neck. If you add ventilation outlets to an unvented gourd, try to put the outlet at the highest point that you can put it.

[Scott D.- La]

Kelly,
I have also experienced this problem in 2007 and lost 25 babies from wet molded nest. My Super Gourds were leaking at the hanging holes and we had hot,humid wet weather on a daily basis. It is imperative to have waterproof, properly vented and mounted gourds to prevent this from happening. If you decide to vent with 3/4 pvc elbow's, you can close them off simply by buying a 3/4 cap and adding a small piece of pipe to the fitting and take it on and off at will. In the early season, it's quite cold when the Martins first arrive. I have all my vents caps plugged that can be plugged. When it warms and condensation starts to build, I know it's time to unplug the vents.

[Kelly Applegate~MN]

Thanks for chiming in on this.....now my suspicions are validated. I'm going to add pvc elbows and the caps for easy on/off venting next season.

Other than this, our martins in Minnesota have had the best year in a long time.....warm weather, patchy rain to keep the insects going, and some colonies have less parasites than ussual.

We had a close call this spring.....we were literally 1 day away from mass martin mortality in a spring cold snap. Luckily, the temps went up and the weather warmed just in time. We did lose quite a few adults in that cold spell....mainly ASY males.

The Minnesota Purple Martin Working Group will have banded approx. 1,500 young and adults this season. We're looking forward to finding them at our roosts soon with a spotting scope.

[Dennis - AL]

I have been following the discussions about using the PVC elbows in the top of plastic gourds for ventilation.

The consensus is everyone thinks the PVC elbows reduce the inside temperatures, thereby cutting down on the potential for condensation build up.

Does this mean that two PVC elbows would be better than one?

Dennis

[Emil Pampell-Tx]

Two is probably better than one, some people do attach two elbows to the top of a gourd.

[Kelly Applegate~MN]

Another landlord here in Minnesota also had trouble with some gourds retaining too much moisture. I'm definitely going to add the pvc elbows with some type of plug to open/close when needed. One tunneled plastic gourd was so bad the young smelled terrible and had feces stuck all over their feathers to the point of not being able to fly. I had to wash the yuck off of each one and that was not an easy task with them screaming and flapping. A big contributing factor is the fecal sacs building up in the tunnel and the birds walking back and forth over it to get food from the parents.

[Brad-AL]

That's odd about the fecal sacs in the tunnels. All my gourds have tunnels, and I have never seen that in the tunnels. Mine usually have a few leaves stuck up under the porch, but that's about it. I wonder if you guys up there have not had some sort of virus run through the birds, or perhaps a perfect year for a large coccidiosis bloom, which would cause the birds to flush. If you weigh nestlings when you band them have the weights been lower than normal this year?

[Kelly Applegate~MN]

Hi Brad,

Martin young are banded at 9-20 days old, it's from about 23-28 that this becomes a problem. In fact, most of the nests are bone dry when we band them. It's interesting that this problem is only serious up here.

It's also interesting that this problem has never happened in our wooden housing, just the plastic gourds with tunnels. My vertical plastic gourds with interior porches were also unaffected. It seemed as though the young could poop under the porch and avoid tracking through it.

In the worst of the horizontal plastic gourds with tunnels, there was fecal matter 1/2" or deeper half way up the tunnel from the inside, an overly wet nest, and young that could not fly properly upon fledging.

-Maybe a virus that hits them in the moist conditions of the gourd?
-A change in insect diet the parents are bringing the last week before fledge?
-Parents that can't keep up with removal of fecal sacs?

I'm going to modify the gourds by adding the vents & cutting off the interior entrance that the tunnels fit over.

[Emil Pampell-Tx]

Kelly, could it be the cool nights are causing the condensation in the plastic? its like a heavy dew inside the plastic gourds. The reason we do not see that down south is because the nights don't get cool enough. When you have the hot days, and cool nights, you would create the fog inside the plastic gourds. The wooden houses would get damp, and the wooden houses do not have tunnels, but the wooden houses would not have the little droplets on the inside. The wood would absorb some of the moisture at night. The plastic gourds would have no way to absorb the moisture except in the nesting material. Also the wood is a better insulator, so it would take the wooden houses longer to have the large temperature difference.

We usually get a heavy fog in the early spring when the earth and water is cold, but the air is warm. That is the same conditions that you have inside a gourd in the far North, the martins create the warmth, and the plastic gourds are cold at night. Its like a dew inside the gourds.

Then when you have unventilated gourds, the cool air cannot enter the gourds quick enough. I think that it would help to have better ventilation, but like you say, then it may get too cool. The babies probably do not give off enough heat to warm the inside, but as they get larger, more heat gets trapped inside the gourds that are unventilated. They also eat larger bugs as they grow older, so more droppings are created. Early in the season when the babies are young, and you may not have the hot days and cool nights

The tunnels probably help contribute to the problem, its even harder for the warm air to escape, so the temp differece remains in the tunneled gourds longer than it does in a gourd without a tunnel.

Seems to me like the wooden houses is the best answer.

This may be why the martins do not like aluminum houses, you probably would have more moisture inside of them also, especially if there were tunnels on the alumnum houses (which you never have of course)

These are some of my thoughts

[Scott D.- La]

I find it " ODD " if anyone has clean nest at the end of the season, much less a clean tunnel. I hear all the time of landlords reusing old nest, that is simply not a option here and all gourds must be cleaned. They are literally....... full of Chit from tunnel to gourd. I must have some trashy Martins here ??? I have never had a nest, even one that wasn't used, that I feel clean enough to reuse. Even the empty gourds that get visitors, soil those nest too. Gourd cleaning is a JOB here, and a nasty one at that, I dread cleaning them every year.

[Emil Pampell-Tx]

Scott, its a difference of opinion, some people see a dirty nest, while a different person would call it a completely filty nest. The description on the same nest would vary greatly. We must have some odd martins, because the nests and tunnels here are not filthy, some are relatively clean

I often wonder how the martins cleaned out the woodpecker holes, that must have been quite a chore for them...smile...What I am trying to arrive at is that a DRY dirty nest will not harm the martins. A WET dirty nest should be replaced. I am removing my gourds now, have 96 gourds taken down. Some are dirtier than others, but they are relatively dry and we have had nearly 12inches of rain in July in the first 21 days. Since they have some excellent sticks in them, I will not completely clean out the nests. I will simply shake out all the droppings that I can after the gourds are completely dry, and reuse them just like that.

The amount of nesting material inside a gourd, the amount of sticks, the amount of material that does not hold water helps determine how wet and dirty a nest gets and stays. Pine needles alone are not the best nesting material because the droppings do not fall thru them, but sticks are the best. Just look at a birds nest on the outside in trees, they use mostly sticks because they stay drier. The same kind of sticks help keep a martin nest dry. That is what I am leaving inside of my gourds, the sticks that the martins brought inside. The martins know what they need much better than we do.

I reused the sticks from last year, left them in the nest, and the martins had the best season ever this year, so it certainly does not hurt to have what you call a dirty nest if its DRY! Also, there were no mites this year, I put a small amount of sevin powder into the gourds when I put them on the racks.

Kelly, I don't mean to hijack your post about nesting material, but I am simply replying to Scott, trying to point out what can and should be left in the nest for the martins. I think its wrong to throw out what the martins want to use. If its good sticks, they should be left in the nest for next year. I leave quite a large pile of sticks inside the gourds, the martins climb on top of them, and the nests stay dry

It may be advisable for you to provide some sticks for the martins to use. They like small thin sticks. A very good alternative would be corn stalks that are cut up into small pieces, the martins like them. Just use something that will help to keep the nests dry. Some of the Amish people sell corn stalks that can be used for nesting material. I am a firm believer that the type of nesting material is very important especially if you have wet stinky dirty nests.

I also think that you need a lot of drainage holes to help keep the nest dry. One or two holes is simply not enough. Sometimes water can stand inside a plastic gourd if the drain holes get plugged and if there are only one or two. Plastic gourds should be designed so that there will be good and adequate drainage.

[Brad-AL]

The nests at my site are dirty, the tunnels are not. They have dry poop in the dry nests, but very little if any in the tunnel. I just call it like I see it.

[Scott D.- La]

Emil,
I get rid of all of it (burn it or compost) and pre nest with new pine straw, small sticks and live oak leaves at the beginning of the season. I always put a pile of small sticks,leaves and more pine straw on the ground if they want to use it. I have noticed one landlord in Florida, who has the nicest cleanest nest I have ever seen. My nest never look that good but do stay dry for the most part. The point to my post was the differences between Martins from area to area. I suppose I could reuse some of the better nest however, pine straw and live oak leaves are so easily obtained here and I am storing all my gourds for the winter in close proximity to some of my personal belonging's in a storage building and want them to be very clean. I have cleaned 16 so far so, your really moving Emil having put away 96 already.

[bbillyc]

This is fantastic information. Why wouldn't Troyer who builds these things have figured that out and retrofit them with the proper ventilation system. I read the above posts and finally figured out why the nests were so wet and stinky even after only a couple of days from nest changes. The sad news is when I bought them I thought they needed more ventilation and bought some pvc elbows to actually provide more venting. But here are problem is more cold than hot, but this summer was extremely hot and humid.

I can't believe I was so stupid and my birds were suffering because of it.