We support wetlands, which is sometimes in conflict with mosquito mitigation. To combat their affects, consider supporting the declining aerial insectivores.
Some time ago, I was asked by the R. W. Norton Art Gallery in Shreveport, Louisiana, for some advice on supporting aerial insectivores in an effort to control mosquitoes in an urban habitat, and this is what I wrote:
Aerial insectivores like bats, swallows, swifts and nighthawks have been in decline worldwide. Aerial insectivores can consume their body weight in insects every day, a greater amount of insects than any other ecological guild (a group of animals that make their living the same way). Because they trawl the air with their mouths open, they consume more than wait-and-jump insectivores (picture a Willow Flycatcher or a frog). This in turn enables them to live this high energy lifestyle where they spend many hours (or in the case of swifts, at least), days on the wing.
One of the most overlooked of the aerial insectivores is the Common Nighthawk. They tend to be attracted to areas where they have bred and fed at in previous years.
Now the challenge is it to keep their habitats suitable. Urban Nighthawks nest on flat, gravel rooftops such as hospitals, schools, and old storefronts. They need the gravel for camouflage and thermoregulation of their incubating eggs, especially important for birds that nest in open areas. Sadly, roofing companies are switching to a white poly composite material that the nighthawks won’t use. Since roofs usually are replaced every 7-10 years, we can expect nighthawks to disappear from urban nesting sites in the next 10 years, perhaps 20 years for old abandoned buildings that aren’t maintained as well. The nice thing about these new roofing materials is that they make buildings more energy efficient, so I can hardly recommend keeping the gravel. The alternative is a mixed-use green roof, in which plants are grown and interspersed with gravel to maximize wildlife use of all rooftop habitats types while also providing energy efficiency. A city planning master’s thesis recently addressed this very question.
The other crucial element is feeding habitat. If folks in urban areas cut neonictinoids (a type of pesticide) out of their plant treatments, that goes a long way. This class of chemicals has been linked to the decline of beneficial insects that might feed on mosquitoes, and might affect insectivorous birds, amphibians, fish, and many more as it travels through the food web. The neonic class of insecticides has been banned by some countries, cities and provinces. Of course, eliminating a pesticide might seem counterintuitive if your goal is to control mosquito populations, but neonics’ indiscriminate influence on the ecosystem has so many indirect effects, that it has the potential to cripple so many parts of the ecosystem, including parts that would control mosquitos naturally.
Nighthawks also like large lighting fixtures found at sports fields and parking lots that attract insects, so that is another urban boon to them and other aerial insectivores. If Nighthawks are using open forests and sandbars, removal of brush from these habitats would encourage their nesting. Nighthawks have long wings and are unable to land at their ground nest sites if there’s too much debris.
What’s best for all of the insectivores is to create habitat for anything that would increase overall biodiversity in urban and suburban areas. This includes keeping your grass a little longer and keeping brush piles to support small reptiles Iike garter snakes that also feed on insects in your yard, and keeping the feral and outdoor house at population very small. Cats feed on recently fledged nighthawks and swallows that tend to be on the ground begging for food from their parents. Overall, cats have overtaken habitat loss as the #1 cause of wildlife loss in North America and have caused some extinctions in other countries. Public education on this subject is critical because it will take a while for our culture to understand the impacts of our beloved pets and how we can change that. Minimizing ambient urban lighting like the large office building in Texas that attracted a large bird strike recently is another thing we can do for biodiversity. Supporting urban barn swallow nests (which are often treated like pests, since they nest over doorways and their waste accumulates on the walkway below) is also important. Rather than destroying nests mid-breeding-season when it is difficult for the birds to recover, I encourage folks to hang scented dryer sheets (that you use for laundry) at the exact point where the bird is building its nest early in the process so that they can build their nest elsewhere.