Purple Martin houses - The best mosquito control?

A male Purple Martin sits atop a perch.

Purple Martins are a species experiencing significant population declines since 1970. These significant drops in martins helped create a call for more artificial Purple Martin houses across their native range. In this conservation push, many organizations offered the beneficial fact of Purple Martins consuming 10,000 mosquitos per day. However, the information offered at the time may not have been entirely accurate.

The loss of Purple Martins

According to the 2019 study, “Decline of the North American avifauna,” Purple Martins have experienced population losses from thirty to forty percent. Some local populations experience severe declines, with some disappearing from the local landscape altogether. Each local population may have experienced severe declines from different factors.

Forest Fires

In Pacific populations of Purple Martins, populations have likely been impacted by a drier climate creating more frequent and more intense fires. This eliminates nesting habitat and lowers the reproductive success of each nest. In the adjacent desert populations, the introduction of invasive plant species has created hotter fires that kill the native saguaro and other plants where martins nest. While these issues heavily impact western martin populations, eastern Purple Martins likely have faced other challenges.

Invasive species

Throughout the forests of eastern and north-central North America, Purple Martins have depended upon the natural cavities created by other native birds and wildlife. Loss of habitat and forest degradation may have played a role in initial declines. However, since the increased use of martin housing, these two deficiencies have likely been balanced. In fact, eastern martin populations may depend upon nestbox colonies almost exclusively. This creates a dangerous situation, as the use of martin housing is on the decline. One of the biggest threats to eastern Purple Martins, though, is also a human-induced problem. The introduction of invasive House Sparrows and European Starlings creates nest site competition that can route any chance for martins to nest without human assistance. These factors still may not be the largest threats to the beloved martin.

Pesticides cause harm

A combined threat for Purple Martins from all regions is the continued use of pesticides. Neonicotinoids and pyrethroid insecticides not only drastically reduce the flying insect availability for martins, other swallows, and flycatching birds, but these pesticides have the potential to build up in the ecosystem, and the bodies of adult and immature birds, impacting the chances for eggs, nestlings, and fledglings to survive to adulthood. This pincer-like threat affects martins at multiple stages of their life cycle but especially creates a bottleneck at what ecologists call recruitment. For all non-ecologists, recruitment is the addition of individuals to an organism's reproductive population through the maturation of young, in this case. For martins, the failed nests and low survival rate of nestlings prevent the potential for more nesting birds, and as adults are lost from the population, no birds are able to replace these lost individuals.

Purple Martins face a significant number of human-caused threats. Fortunately, creating bird-friendly spaces and combining them with multiple Purple Martin houses can create the optimal opportunity for a martin colony to arrive and thrive!

Create a Purple Martin nesting colony

Purple Martins are gregarious birds, meaning they will nest, roost, and migrate in large numbers. While most nesting colonies are twelve pairs of martins or less, this may be due to the size of the typical martin house. For bird lovers that erect multiple houses, their homes might draw up to thirty-five nests! There is a report of a nesting colony of over three hundred nests, though the validity of this report is not fully verified. Creating a premium landscape for a Purple Martin colony may take some work, but the easiest step is acquiring the house.

The starling-resistant Purple Martin house

Building a Purple Martin house requires following a very precise set of procedures. Builders will want to create a space that is preferred for martin nesting while also limiting access for invasive cavity nesters like the European Starling. Those with toolboxes that are lacking may not find this option appealing. Here is where Birds Choice can offer a great alternative, the sixteen-room Purple Martin house with starling-resistant entrance holes. This simplifies the process for the less-than-handy homeowner, as this home comes preassembled. Additionally, our houses are made from aluminum which will last longer than wood and plastic while keeping the nests cooler inside. The nest box hotel is the first step to creating a martin colony. The next step? Create a habitat that benefits Purple Martins.

A home for a Purple Martin house

Yes, the martin hotel is necessary for these colonial birds to nest. But the surrounding habitat is what turns the Purple Martin house into a Purple Martin home. For eastern Purple Martins, edge and riparian habitats are crucial to creating an open space that is packed with flying arthropods. While historically, martins would have nested in woodpecker holes in large trees, putting the birdhouse in an open space simulates this requirement while keeping the nests close to feeding zones.

Western Purple Martins were less likely to use nest boxes in previous years, but recently, these houses have become paramount to the nesting success of this species in many of the Pacific states. For the few breeding colonies in the Rockies, martin boxes are unlikely to be used. Mature aspen groves are essential to nests for these birds found in the intermountain west. The Purple Martins residing in the desert southwest reside almost solely in saguaro forests, but some can be found in rock crevices if suitable habitat is not available. While many of these mountain and desert populations are not known to use martin boxes, they may eventually need these houses to complement their degraded habitats.

A safe house and a happy home create a Shangri-La for these large, violet swallows. Two more ingredients are still needed for an Eden for aerial insectivores.

Avoid pesticide use in bird-friendly yards

As mentioned above, pesticides may be one of the most detrimental human-induced activities that martins face. Eliminating pesticide use keeps Purple Martins and nestlings safe during the breeding season. One way to significantly reduce pesticide use is to convert non-native yards and gardens into native landscapes with plants that are adapted to surviving against pest infestations. 

For the blood-sucking pests, empty stagnant water sources out or keep those ponds and birdbaths agitated and moving. This discourages mosquitos from being lured in to lay their eggs. And while many have been led to believe that Purple Martins help keep mosquito swarms in check, there is a revelation still to come in this article that will change perspectives.

Bird-friendly yards make for healthy water, people, and Purple Martins.

Purple Martin range

Of course, the most important element of attracting Purple Martins is living inside the bounds of their range! Purple Martins are found from the eastern Great Plains to north-central Canada to the Atlantic Coast. There are separate subspecies and populations on the Pacific Coast, in the Rocky Mountains, and throughout the saguaro forests of the desert southwest. Without living in these areas, martin maniacs are unlikely to host their own colonies.

Do Purple Martins control mosquitos?

Simply, no. Unfortunately, the often-cited fact that a single Purple Martin can eat up to ten thousand mosquitos per day is not only overblown but is entirely incorrect. Martins and other swallows do eat flying insects. However, bird researchers studied the feeding habits and the stomach contents of Purple Martins and came to the conclusion that martins eat very few to no mosquitos. The martins feed at different altitudes than the mosquitos fly or swarm at, making the likelihood of mosquito consumption to be next to zero. So, no. Purple Martins are not much of a mosquito control method.

BUT!

While Purple Martins do not eat mosquitos on a regular basis, they still do eat hundreds, if not thousands, of other flying insects and pests each day! Insects that can cause crop damage, bite or sting, or are otherwise just viewed as a nuisance to civilized folks. Hope is not lost. The Purple Martin can still be our dark knight, cruising the skies and keeping our yards a little safer from the insects so many cast their disgust upon. But you will need to keep using that citronella.

If you build it (and follow the instructions above), they will come

Purple Martins are a highly desired yard visitor. While they may not control mosquitos as we hope, they will help keep other insects in order, allowing homeowners to focus their attention on mosquito abatement. The shift of younger populations moving to urban areas will only continue to put Purple Martins at risk, as the population of rural dwellers with martin houses may shrink. Bird lovers and conservationists can unite against this by building more homes, creating healthy habitats, and breaking away from our over-dependency on pesticides.

Be a good neighbor and share some space with the local Purple Martins.