Our last blog post touched on one of the reasons that purple martin nestlings jump prematurely out of their nests. Referred to as “jumpers” these youngsters are often doomed. The reason why I, along with many other South Florida landlords, have seen a huge increase in jumpers this year over previous is our record breaking drought conditions. Dry weather means fewer bugs which means purple martins go hungry and nesting success plummets.
The main reasons that martin landlords encounter jumpers are: parasites, extreme heat and hunger. Drought, though not a specific reason, contributes to low food supply and hunger/malnourishment.
Parasites can torment young inside a nest. Though some have argued that nature should be allowed to take its course, the natural instinct of the Purple Martin (Progne subis, subspecies: subis) has been altered by man. Before Native Americans created the tradition shift in martins, the nest sites of these birds were tree snags and they nested farther apart. You can read about some of the history of martins at our parent site: PurpleMartins-R-Us.com. They were much like their West coast cousins, Progne subis, subspecies: hesperia and subspecies: arbicola. The shift not only affected were they nested (tree snags vs man made houses) but the way they nested, as it is believed they were not as colonial in their nesting. That is to say, they were spaced further apart and did not nest in such large groups. The groups of martins nesting in close proximity can create parasite population explosion. We counter this by periodic nest changes and/or the use of a small amount of Sevin. We have a great link to a video on how to do a nest change.
Extreme heat in a nest can be challenging to combat but if not associated with drought or food shortages, are usually easy to remediate. By making sure all vents are open in nest compartments and gourds, air circulation can be increased which can help lower temps. Many artificial gourds have vents that can opened as an option. For example Troyer gourds have built in mini vent canopies that can be drilled open easily. We recommend drilling these open before the season but a cordless drill can open those up quickly. If those are too small or you want larger vents (more air circulation) than a 1/4 inch threaded PVC elbow (90 degrees) is perfect for the job. It can be easily installed on any gourd or house for that matter to increase air flow. Just drill a hole large enough to thread the end in and caulk in place. Make sure it points down and, if you want, attach a small piece of screen to cover the opening to allow air in but keep wasps out. The picture shows a modified gourd with elbow in place at the highest point which will push out the hot air as it rises. Know that in Northern climates you may have to plug these vents inn the early spring in times of cold weather to keep your martins warm.
Other tricks folks employ:
Using a frozen gel pack placed in an empty compartment. A frozen bottle of water can be used also.
A secondary shade can also help. Placing a sunshade to keep the sun from beating down on the house surface can decrease temps.
-------photo by OakleyOriginals on Flickr
Even a misting system has been used by many with success. Just makes sure the water does not go into compartments which would lead to wet nests. Also the misters should only run intermittently in the hottest part of the day so that the water can dry off. The evaporation is what cools. Don’t let the misters run at night or continuously. Our Free Purple Martin House Plans page has instructions available on how to make a mister system for your martin houses.
Hunger is a difficult problem and the debate is heated on how much humans should intervene on this. Though supplemental feeding is often done in early spring cold snaps for returning adults, one should strongly weigh the consequences of feeding purple martin nestlings. Remember that if you have several nests that are doing poorly from lack of food, the parents are suffering also. If there is a long term problem, supplemental feeding is a very short term solution. Read our Emergencies page for first responder care of purple martins.
What other problems lead to Purple Martin nestling Jumpers? Let us know what you think.
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