Purple martins are unique birds that have a special relationship with humans. These large, fast-flying swallows readily nest in man-made birdhouses, making them beloved backyard birds across much of North America. Providing proper habitat is key to attracting and keeping purple martins nearby. One important habitat consideration is the proximity of open water.
Why Do Purple Martins Need Access to Water?
Like all animals, purple martins need water for drinking and bathing. Access to open water is especially crucial because:
- Purple martins eat only flying insects, which they catch in flight. Flying and catching insects leads to rapid water loss.
- Purple martins are aerial insectivores, meaning they feed exclusively on insects caught while flying. They can consume up to 2,000 flying insects in a day!
- Feeding on the wing causes purple martins to lose a lot of moisture through respiration and exposure to drying winds.
- Bathing helps purple martins stay cool and control parasites. Frequent bathing is important so they can continue flying and feeding efficiently.
- Nestlings need ample moisture as they grow and prepare for their first migration.
During hot, dry conditions purple martins may bathe numerous times per day. If open water isn’t available near the nesting site, purple martins may abandon a colony.
How Close Should the Nearest Open Water Be?
Most purple martin experts recommend situating nesting sites within 1⁄4 mile (400 meters) or closer to open water. However, martins may travel farther when needed. Some key factors to consider include:
- The natural landscape – Is the habitat semi-arid or swampy? Purple martins in drier regions may need water sources placed closer to their housing.
- Weather conditions – During periods of hot, dry weather martins will visit water more frequently and require sources well within 1⁄4 mile.
- Type of water source – Large ponds, wetlands, and rivers hold appeal. Small birdbaths may be unsuitable for groups of energetic purple martins.
- Competing birds – If grackles, starlings, or sparrows dominate a small water source, martins may avoid it.
- Predators – Martins are vulnerable to hawks and other aerial predators when flying between water sources and their nesting colony. Minimizing this distance increases safety.
Because purple martins prefer to nest colonially, or in groups, providing adequate water nearby helps attract multiple pairs. Groups of martins can work together to drive off problematic species. Ensuring a reliable, easily accessible water source near housing allows groups of martins to thrive.
Ideal Purple Martin Water Sources
What types of open water do purple martins prefer? Here are ideal water sources to have within 1⁄4 mile of a nesting colony:
- Ponds: Medium to large ponds (ranging from 15 x 25 feet up to an acre or more) provide optimal water habitat. Martins need space to swoop down to the water’s surface for drinking and bathing. Ponds surrounded by sparse trees are best.
- Wetlands: Marshes, sloughs, and swamps give purple martins excellent natural water access. Wetlands rich with insects are especially attractive.
- Streams and rivers: Slow to moderately flowing watercourses allow purple martins to dip and bathe. Rivers and streams should have banks and islands for perching.
- Lakes: Larger lakes provide good habitat. Purple martins frequent lake shorelines, islands, and inlets protected from wind and waves.
- Estuaries: Estuaries where rivers meet the ocean provide food, freshwater, and roosting spots for purple martins.
Avoid small backyard birdbaths for martins. While songbirds use birdbaths, energetic purple martins prefer larger bodies of water. Small containers may also facilitate the spread of diseases.
Creating or Enhancing Water Habitat for Martins
If natural water sources are lacking near your purple martin housing, consider creating new habitat. Some options include:
- Installing a medium to large pond, minimum 15 x 25 feet.
- Developing a wetland area if your property has adequate space.
- Diverting part of a stream to create a new channel nearer the housing.
- Flooding a portion of pasture to make a temporary seasonal pond.
- Providing a galvanized stock tank, kept clean and algae free.
Be sure to follow any regulations when creating new water habitat. Monitoring mosquito larvae may also be necessary.
Enhancing natural areas can also help. Removing invasive plants along a lakeshore provides more open space. Clearing dense trees from a wetland creates better flight access. Installing perches near water allows purple martins to survey for insects and rest.
Where Should Housing Be Located Relative to Water?
Purple martin housing should be situated between their water source and prime feeding areas. Housing located near water but also within sight of large open fields, wetlands, or river corridors gives martins convenient access to food, water, and nesting.
Avoid placing housing on the opposite side of the water source from feeding habitat. This forces martins to make excessive flights back and forth.
Housing should also be placed away from trees or buildings directly on the shoreline. Martins need an open flight path when approaching their nest cavities.
Can Natural Predators Limit Housing Placement?
Yes, the presence of certain predatory birds can affect where purple martin housing is sited. Key predators include:
- Falcons
- Hawks
- Eagles
- Owls
- Ravens
- Crows
Aerial predators like the falcon can snatch martins from the sky. Raptors may raid nests for eggs and nestlings. Crows and ravens can harass adults and displace entire colonies.
It’s best to avoid placing martin housing within 1⁄4 mile of known nests or regular perches used by predatory birds. Limiting the distance purple martins must travel from housing to water helps minimize predation risk.
Will Purple Martins Use Bird Baths or Small Backyard Ponds?
Purple martins prefer natural ponds, lakes, wetlands and other larger open water. Small backyard features like birdbaths may receive little use, for several reasons:
- Typical birdbaths are too small. Energetic martins need room to dip and swoop.
- Baths placed near trees increase the risk of predator ambush.
- Dense shrubbery blocks open flight paths martins require when approaching water.
- Small ponds allow little room for group bathing and drinking.
- Backyard water sources often have high competition from other birds.
That said, purple martins may utilize small water features if no larger water is available nearby. Limiting vegetation around birdbaths and ponds can increase usage. Perches allow martins to survey the area before bathing. Avoid deep-sided containers that could trap fledglings.
Special Considerations for Providing Water in Natural Cavities
Some purple martin enthusiasts prefer housing the birds in natural cavities rather than man-made nest boxes. Natural cavities may be in dead trees, woodpecker holes, crevices, and similar sites.
If housing martins in natural holes, be sure to place cavity sites within 1⁄4 mile or less of quality open water. Natural cavities provide less protection from weather, predators, and competitors. Minimizing the distance martins must travel for bathing and drinking is especially important.
Natural cavities are also harder to monitor. Being unable to readily view nests makes quick, easy access to water vital. Fledglings may even leave the nest early if water is too distant.
With proper planning, both natural and man-made purple martin housing can successfully accommodate these special birds. Paying attention to their water needs is one key to thriving colonies.
Conclusion
Purple martins require open water within approximately 1⁄4 mile or less of their nesting sites. Close water access enables them to stay hydrated and regularly bathe as they feed on insects caught during continuous flight. Ponds, lakes, rivers, wetlands and other natural waters provide the best habitat.
If adequate water is not present near housing, creating or enhancing water resources can help attract martins. Housing should be located between water and prime feeding areas with an open flight path. Providing quality water habitat close to nesting sites helps create thriving purple martin colonies.
