The Brown Creeper is a small North American songbird in the Certhiidae family. It is known for its cryptic brown plumage and slender, curved bill that allows it to probe into bark crevices as it creeps up the trunks of trees. Brown Creepers nest in natural cavities or behind loose bark on dead trees or dying branches of live trees. Their nests are well-camouflaged and can be very difficult to spot. This article will explore in detail the nesting habits of the Brown Creeper, including where they build their nests, what types of trees they use, and other interesting facts about their breeding biology.
Nest Placement
Brown Creepers nest in a variety of habitats across North America, but they show a strong preference for older forests with plenty of dead and dying trees. Mature forests provide the Brown Creeper with an abundance of foraging and nesting sites. The specific placement of Brown Creeper nests varies, but they are most often found behind loose bark on dead trees or in cavities in living trees.
Dead Trees
Dead trees, or snags, provide prime nesting locations for Brown Creepers. They prefer snags that are partially decayed and have bark that is peeling away from the trunk. The space between the loose bark and the tree trunk creates a protected cavity where the Brown Creeper can build its nest. Natural cavities caused by rot and woodpecker holes may also be used. Brown Creepers often nest fairly low on snags, typically between 3 to 30 feet above the ground. However, they have been recorded nesting as high as 60 feet up in some large snags. The diameter of nest trees ranges from 4 inches for small saplings up to several feet for mature snags.
Living Trees
In addition to dead trees, Brown Creepers will also nest behind loose bark on living trees. These are usually mature trees that are damaged or diseased. Species commonly used include aspen, cottonwood, hickory, oak, and birch. As with snags, the bird requires bark that has peeled away from the trunk to create a space for the nest. Woodpecker cavities in living trees are also prime real estate for Brown Creeper nests. These cavities provide more insulation and protection than nests behind loose bark.
Tree Species
The Brown Creeper is not overly selective about the species of tree it nests in. The keys are mature forests with plenty of snags and dying trees that provide suitable nest sites. However, there are certain tree species that Brown Creepers seem to favor when available:
Conifers
In coniferous or mixed forests, Brown Creepers often nest in dead pines, firs, and spruces. The flaky, shaggy bark on these mature conifers provides ideal concealed spaces for nests. In the Pacific Northwest, western red cedar snags are commonly used. Across Canada, jack pine forests harbor many Brown Creeper nests.
Oaks
In deciduous forests, oaks (Quercus spp.) are a preferred nest tree for Brown Creepers. Oaks have deeply furrowed, textured bark that offers excellent nesting opportunities. Dead oaks are prime real estate, but living oaks with damaged areas are also selected.
Other Hardwoods
Beyond oaks, Brown Creepers use a variety of other hardwood tree species. These include:
- Aspen
- Birch
- Cottonwood
- Hickory
- Maple
- Sycamore
- Willow
Any of these tree species are likely to be used if they have loose, shedding bark and are found in mature forest habitats.
Nest Construction
The actual nest of the Brown Creeper is a remarkably crafted cup of twigs, bark, mosses, and other forest materials. It is wedged into the cavity behind the loose bark or in a crevice of the tree trunk. Nest construction is done primarily by the female over 6-8 days. Here are some key facts about Brown Creeper nest building:
- Nests average 4.5 inches across and 2.5 inches tall internally.
- The foundation is made of small twigs, rootlets, and strips of bark.
- This is lined with softer materials like mosses, animal hair, grass, and fine bark fibers.
- The exterior is wrapped in spider egg cases and flakes of bark to disguise it.
- Nests are typically placed 4-20 feet above the ground.
The female intricately weaves this essential cradle for her eggs and nestlings largely out of materials gleaned from the nest tree itself. The end result is a snug, beautifully camouflaged nest that is nearly impossible to spot among the textures of the tree bark.
Geographic Range
Brown Creepers nest throughout much of North America from Alaska across Canada and south to higher elevations in the western mountains and to the Carolinas in the East. Here is more on the geography of Brown Creeper nesting:
Western North America
In western North America, Brown Creepers nest from southeast Alaska south along the Pacific Coast to California. They can be found breeding in coastal forests and throughout mountain ranges like the Cascades and Sierra Nevada. Their range extends east into the Rocky Mountains.
Eastern North America
In eastern parts of the continent, Brown Creepers nest across Canada and the northeastern United States. Their breeding grounds extend from Newfoundland to Manitoba and south to the Great Lakes states. At higher elevations they nest as far south as Georgia and South Carolina.
Wintering Range
Brown Creepers retreat from northern parts of their breeding range in winter. They can still be found year-round through much of the western and northeastern U.S. but are absent from the northern boreal forests. Wintering birds are often seen creeping up tree trunks together in mixed flocks with nuthatches, chickadees, and kinglets.
Nesting Facts and Behavior
Beyond where they place their nests, there are many fascinating facts about the nesting habits and breeding behavior of Brown Creepers:
- Brown Creepers are solitary nesters. Each pair has their own territory surrounding the nest.
- They usually raise just one brood per year. The female lays 3-8 eggs over 1-2 weeks.
- Only the female incubates the eggs. Incubation lasts 12-14 days.
- Nestlings fledge at 14-17 days old but remain dependent on the parents for 2-3 more weeks.
- Both parents feed the young, gathering insects from nearby trees.
- Predators like squirrels, raccoons, and raptors may raid nests. But the well-hidden sites help avoid detection.
- Old nests are not reused. New nests are built each spring in suitable cavities.
From nest construction through raising their brood, Brown Creepers demonstrate specialized adaptations for nesting on tree trunks. Their reliance on mature forests underscores the importance of preserving old-growth habitats.
Threats and Conservation
The Brown Creeper’s dependence on older forests makes it vulnerable to habitat loss from logging and development. Other threats include:
- Fragmentation of forest habitat which reduces nest sites and foraging areas.
- Firewood gathering removes dead trees used for nesting.
- Increasing predation as edge habitats encroach on forest interiors.
However, Brown Creeper numbers remain relatively stable across most of their range. There are several conservation measures that can help protect them:
- Preserve contiguous tracts of mature forest with snags and dying trees.
- Leave buffer zones around nesting areas when tree harvesting occurs.
- Allow wildfires to burn in a controlled manner to create future snags.
- Monitor Brown Creeper populations and adapt forest management as needed.
Ensuring sufficient high-quality nesting habitat remains available will be key to the continued success of the Brown Creeper. Careful forest management practices that balance ecological and economic goals are vital.
Conclusion
In summary, the Brown Creeper is a specialized bark-nesting songbird that relies on mature forests across North America. It builds beautiful, well-hidden nests behind loose bark or in cavities of both living and dead trees. Brown Creepers are not limited to specific tree species as long as conditions are right for nesting. While they face some habitat threats from logging, their populations remain stable when adequate nest sites are preserved. Maintaining healthy, biodiverse forests with standing dead trees will ensure the Brown Creeper continues to creep up tree trunks in search of food and nesting sites for centuries to come.