Brown Creepers are small brown birds that creep up the trunks of trees searching for insects to eat. They have a very specific habitat preference and are most often found in mature forests with large trees. Knowing what tree species Brown Creepers prefer can help us understand more about their habitat needs and how to best protect them.
The Brown Creeper (Certhia americana) is a small songbird found across North America. It is a member of the treecreeper family Certhiidae. Brown Creepers are non-migratory, staying year-round in their breeding habitats. They have a very specialized lifestyle, spending their time creeping up the trunks of trees searching for insects. Brown Creepers prefer forests with large, mature trees. Their population numbers have been declining in recent decades as old-growth forests are logged. Understanding the tree species preferences of Brown Creepers can help guide habitat management programs aimed at protecting this species.
What Trees Do Brown Creepers Prefer?
Research studies have found that Brown Creepers show preferences for certain tree species over others. In general, they prefer larger, older trees with more crevices in the bark where insects hide. Some key tree species that Brown Creepers favor include:
- Oaks – Studies have found oaks, especially mature oak trees, are preferentially used by foraging Brown Creepers. Oaks have deeply grooved and furrowed bark that provides excellent habitat for insects.
- Hickories – Like oaks, hickory trees have ridged, shaggy bark that attracts insects. Brown Creepers often forage on mature hickories.
- Maples – Old maples have furrowed bark that Brown Creepers can probe for insects. Maples are commonly used by Brown Creepers, especially sugar maples.
- Ashes – Mature ashes have vertically split bark that creates great creeping and probing substrate. Brown Creepers frequently use ashes.
- Elms – With age, elm trees develop deep furrows in their bark. These furrows are perfect for Brown Creeper foraging.
- Black Walnut – The deeply ridged bark of black walnuts makes them a preferred tree for Brown Creepers.
In addition to the tree species listed above, Brown Creepers may also use trees such as American beech, yellow birch, eastern hemlock, eastern white pine, and sycamore. However, research shows they preferentially select tree species like oaks, maples, and hickories that have especially deep, furrowed bark.
Why Do Brown Creepers Prefer These Tree Species?
Brown Creepers have very specific habitat needs. They require certain tree characteristics in order to thrive:
- Large diameter trunks – Brown Creepers need wide trunks to creep along vertically.
- Deeply furrowed, loosely peeling bark – The cracks and crevices in rough bark provide places for insects to hide. Brown Creepers probe their slender, curved bills into the bark furrows to find insects.
- Large trees with high insect abundance – Big, mature trees support more insects for Brown Creepers to eat.
- Trees spaced far enough apart for creeping – Brown Creepers need space between trees to allow creeping up trunks unobstructed.
Tree species like oaks, hickories, ashes, and maples are preferentially selected by Brown Creepers because they fulfill these habitat needs. Their large diameter trunks and deeply furrowed bark provide ideal creeping and foraging substrate. Additionally, old individuals of these species tend to have high insect loads. Brown Creepers have evolved to excel at extracting insects from the complex bark of these mature, rough-barked trees.
Tree Characteristics that Deter Brown Creepers
Just as there are certain tree characteristics that attract Brown Creepers, there are also some traits that deter them or make trees less suitable habitat:
- Small diameter trunks – Younger, smaller trees don’t allow proper vertical creeping.
- Smooth bark – Trees with smooth bark like beech and birch provide poor foraging and fewer insects.
- Wetwood – Trees with bacterial wetwood ooze make foraging more difficult.
- Dense spacing – Tightly packed stands restrict movement between trunks.
- Absence of branches – Brown Creepers need some low branches to descend to the base of trunks.
In general, small-diameter trees with smooth bark and dense spacing are avoided by Brown Creepers. Groves of young aspen or birch, for example, would offer poor habitat. Ideal forests for Brown Creepers have large, mature trees with rough bark that are spaced adequately far apart.
Geographic Variation in Tree Species Use
Brown Creepers occupy a wide geographic range across North America. From eastern hardwood and coniferous forests to western mountain pine forests, they inhabit many forest types. Not surprisingly, the trees preferentially used by Brown Creepers varies across their range depending on tree availability. Several examples include:
- Northeast – maple, beech, birch, hemlock, oak
- Southeast – oak, hickory, pine, sweetgum, baldcypress
- Midwest – oak, elm, hickory, walnut, cottonwood
- Southwest – oak, juniper, pine, sycamore
- Northwest – Douglas fir, western larch, ponderosa pine, quaking aspen
Regardless of geographic region, Brown Creepers consistently select larger trees with deeply furrowed bark when available. But they demonstrate flexibility in using different common tree species across their range.
Ideal Brown Creeper Habitat
Based on Brown Creeper tree preferences, we can describe ideal Brown Creeper habitat as follows:
- Mature forest with large diameter trees
- Tree species composition includes oaks, maples, hickories, ashes, etc. with deeply furrowed bark
- Adequate spacing between trees for movement
- Some standing dead trees and fallen logs
- Areas of intact forest greater than 25 acres
- Riparian corridors through forested areas
- Elevations up to 10,000 feet
- Multi-layered canopy structure
Old-growth forests with a diversity of appropriate tree species and structures are best for providing quality Brown Creeper habitat. Unfortunately, logging of mature forests has reduced available habitat in many areas. Promoting natural forest succession and preserving old stands will benefit Brown Creeper populations.
Using Brown Creeper Habitat Needs in Forest Management
Public land managers and private forest owners can use knowledge of Brown Creeper tree preferences to guide management practices aimed at conservation:
- Protect existing mature oak, hickory, maple, and ash stands from logging
- Allow new forest growth to achieve old-growth characteristics before harvesting
- Employ selective harvesting focused on smaller diameter trees
- Retain patches of standing dead trees and downed logs
- Maintain adequate spacing between mature trees after thinning
- Prioritize conservation of riparian areas
- Discourage fragmentation and promote large intact forest blocks
Using these kinds of practices, land managers can provide quality habitat for Brown Creepers while still allowing sustainable forest use. A balance of managed timber production and setting aside old-growth stands and buffers along waterways will benefit Brown Creepers.
Threats to Brown Creeper Habitat
The specific habitat needs of Brown Creepers makes them vulnerable to certain habitat changes:
- Logging of mature, old-growth forests
- Forest fragmentation from roads, development, etc.
- Loss of standing dead trees and downed logs to firewood cutting and cleanup
- Invasive insects killing favored tree species like hemlock, ash, and oak
- Short timber harvest rotations not allowing new old-growth to develop
- Grazing and browsing that degrades understory and sapling trees
To ensure healthy Brown Creeper populations, conservation practices are needed to protect remaining old forests, allow new mature stands to develop, and maintain important habitat structures like snags and downed logs.
Research Needs
While we know much about the general habitat preferences of Brown Creepers, there are still research needs, including:
- More region-specific data on tree preferences, which likely vary across their range
- Understanding effects of invasive species like emerald ash borer on habitat quality
- Studying long-term population trends and survivorship in fragmented vs. intact forests
- Investigating optimal configurations of timber harvests and old-growth reserves
- Researching value of riparian buffers through forests
- Expanding mapping of high-quality habitat areas to focus conservation efforts
Filling these research gaps will help enhance forest management strategies for the benefit of Brown Creepers and other mature forest species.
Summary
In summary, Brown Creepers are strongly associated with larger, older trees that have deeply furrowed bark such as oak, hickory, maple, ash, and pine. They use the ridges and crevices in the bark to find insects to eat. Brown Creepers favor mature forests with an abundance of these rough-barked tree species. While they demonstrate some geographic variation in tree preferences, conservation of remaining old-growth stands and encouragement of new forest growth are key to providing quality Brown Creeper habitat across their range.
Conclusion
Brown Creepers are fascinating birds uniquely adapted to creeping up tree trunks in search of food. Their specialized habitat preferences center around mature forests with large, rough-barked trees that harbor plentiful insects. Oak, maple, hickory, ash, and pine trees with deep furrows, ridges, and loose bark allow Brown Creepers to find insects to eat. These birds avoid smaller diameter, smooth-barked trees in dense young stands. By protecting remaining old-growth and managing forests to develop new mature stands, we can provide the habitat Brown Creepers need and allow these specialized birds to continue creeping up tree trunks into the future.
