Phoebes prefer open wetland areas to nest in.

By Steve Mueller

Shift in bird nest sites

Questions from Joan.
Where did chimney swifts nest before there were chimneys?
Chimney swifts continue to be resident throughout Michigan. Even in areas with fewer human residents, Chimney Swifts continue to be present. This likely indicates they still use natural cavities. Most swifts are in southern Michigan where chimneys abound. Lesser numbers are presents in the Northern Lower Peninsula with an increase again in the Upper Peninsula. I suspect the large number of hollow trees left standing in the UP benefit swifts and I encourage people to leave dead trees stand. Too much tidiness is unnatural and not in the interest of increasing biodiversity for a healthy ecosystem.
Where did barn owls nest before there were barns?
Michigan’s Barn Owl population is peripheral to the species primary range. Prior to human settlement nesting occurred in tree cavities, rock crevices, or on ledges mostly outside of Michigan. Native prairie habitat extended into southwestern Michigan and was used by Barn Owls. Suitable barn nesting sites were created after the clearing of Michigan’s forest and this aided range expansion for the birds. Hayfields provided food for voles and subsequently voles for owls. Now Barn Owls are currently accidental residents due to Michigan returning to a forested state, loss of abundant grassland vole habitat, and predation by Great Horned Owls. Small size grasslands make Barn Owls vulnerable to neighboring Great Horned Owls that live in surrounding forests. Do not confuse Barn Owls with Barred Owls.
Where did phoebes nest before there were overhangs and bridges?
Phoebes prefer somewhat open riparian and wetland areas compared to heavily forested areas. They have continued to be abundant throughout the state from pre-European settlement to present. There has been a shift in nesting occurrence from ledges, crevices, and fallen trees to the preferred human constructed sites. Our carport has been a choice site for the 32 years we have lived at Ody Brook. Near the carport I have attached a ledge platform to a tree for phoebes and robins but it has not been used. That nest structure is similar to a birdhouse with no front wall.
Where did martins nest before there were martin houses?
Early records indicated that Purple Martins used tree cavities near wetlands and lakes and were more abundant closer to the Great Lakes than inland. Reports indicate they used cavities in buildings but this use decreased as cities became larger and competition with starlings grew. Michigan approaches the climate tolerance and numbers decrease markedly as one gets north of our area. The blizzard of April 1982 trapped Michigan Audubon conference attendees in Grand Rapids and local birders provided lodging until roads were open. That storm devastated the martin populations through starvation. The population has not yet recovered in thirty years to the pre-1982 size. The cold spring this year likely caused martin starvation by delaying insect population emergence. Of course, healthy streams are essential for insect abundance and healthy nature niches. Thanks to volunteers that recently cleaned Cedar Creek.
Natural history questions or topic suggestions can be directed to Ranger Steve (Mueller) at odybrook@chartermi.net  or Ody Brook, 13010 Northland Dr, Cedar Springs, MI 49319-8433.