Brown creepers are small brown songbirds that belong to the family Certhiidae. They are found throughout much of North America, particularly in forests. Brown creepers are known for climbing up tree trunks and branches as they forage for insects hidden in the bark. Their physical adaptations, behavior, habitat, diet, and other key identifying traits make the brown creeper a fascinating bird to observe.
What does a brown creeper look like?
Brown creepers have streaked brown upperparts which provide camouflage against tree bark. Their underparts are whitish. They have a long, slender, curved bill which is perfect for probing under loose bark. Their tails are stiffened and function as a prop while they creep up tree trunks.
Brown creepers are small birds, measuring 5.5–6.3 in (14–16 cm) in length with a wingspan around 10 in (25 cm). They weigh just 5–14 g. Key physical traits include:
- Streaked brown upperparts provide camouflage
- Whitish underparts
- Long, curved, slender bill for probing under bark
- Stiffened tail feathers used as a prop against the tree trunk
- Small body size – 5.5–6.3 in (14–16 cm) length
- Wingspan around 10 in (25 cm)
- Very light body weight – just 5–14 g
The brown creeper’s brown-streaked plumage provides excellent camouflage as it creeps up the trunks of trees. It blend in seamlessly against the bark. The brown, tan, and white streaking matches the lichens and cracks in tree bark perfectly.
How do they behave?
Brown creepers display some very distinctive behaviors as they forage:
- Spiral up tree trunks in search of insects hidden in the bark
- Use stiffened tail feathers as a prop against the trunk
- Fly down to base of tree and start spiraling up again
- Travel trees in flocks outside of breeding season
- Make very high-pitched call while foraging
- Male performs song flight display during breeding season
Creepers spiral up tree trunks, starting low and working their way up in a corkscrew pattern. They use their stiff tail feathers as a prop against the bark for balance and leverage as they creep upwards. Once they’ve reached the top of the trunk, they fly down to the base of another nearby tree and start spiraling up again.
Outside of breeding season, brown creepers form foraging flocks that travel together from tree to tree. Their contact call is a very high-pitched squeak. During the breeding season, male brown creepers perform a display called the song flight, singing a warbling song while flying in loops with slow, fluttering wing beats.
What habitat do they prefer?
Brown creepers inhabit primarily mature forests across North America. Their preferred habitats include:
- Mature deciduous forests
- Mature coniferous forests
- Mixed deciduous-coniferous forests
- Areas with many dead trees and fallen logs
Mature forests provide better foraging opportunities, with more trees having loose, peeling bark where insects hide. Brown creepers favor forests with a mix of tree species and a variety of tree sizes and ages. Dead trees (snags) and fallen logs are also important, providing nesting sites.
During winter, brown creepers expand their habitat range to include younger forests, wooded parks, and suburban areas with enough trees. However, mature forests appear to be the primary habitat. Elevation-wise, brown creepers can be found from sea level up to the tree line in mountainous areas.
What do they eat?
Brown creepers are insectivores, feeding on small insects and spiders they find hidden in crevices in the bark of trees. Their diet primarily consists of:
- Spiders
- Bark lice
- Bark beetles
- Caterpillars
- Ants
- Other small insects
Using their long, curved bill, brown creepers are able to probe deeply into cracks in the tree bark to find well-hidden insects other birds can’t access. They slowly work their way up tree trunks and along branches, methodically covering every inch in search of food.
Brown creepers are dependent on finding insect prey on and under tree bark. During winter when insects are scarce, creepers may be hard-pressed to find sufficient food. Harsh winters can lead to increased mortality.
Interesting facts about brown creepers
Beyond their physical appearance and habits, there are some other interesting facts worth noting about brown creepers:
- They have unusually flexible ribs that allow them to flatten their body against the bark as they creep upwards.
- Their toes function like a woodpecker’s, with two pointing forward and two pointing back to provide a better grip.
- Nestlings have a sharp, curved tooth on the end of the upper mandible used to repeatedly tap the adult’s bill, stimulating regurgitation of food.
- They build camouflaged, hammock-like nests tucked behind loose tree bark up to 60 ft high.
- Brown creepers rarely reuse a nest site and often build a new nest each year.
- They are non-migratory across much of their range, remaining in the same area year-round.
From their flexible ribs allowing them to hug bark better to the unique way their young beg for food, brown creepers exhibit some fascinating and often overlooked traits. Their nest-building behavior and limited migration patterns also make them unique among small North American songbirds.
How to identify a brown creeper
Brown creepers can be identified based on the following key characteristics:
- Spiraling upward movement on tree trunks
- Stiffened tail feathers used as a prop against the bark
- Long, slender, curved bill
- Camouflage brown upperparts with streaks and bars
- Whitish underparts
- Small body size – about 6 inches long
- Frequents mature forests
- Very high-pitched call while foraging
The brown creeper’s distinctive upward spiral movement on tree trunks, along with its specialized body shape and markings, make it simple to identify. Just look for a small brown bird creeping up a tree trunk in a mature forest while making high-pitched squeaks!
How do brown creepers reproduce?
Brown creepers breed during spring and summer. They are monogamous, mating with one partner per season. The breeding behaviors of brown creepers include:
- Males attract females through song flight displays
- Both sexes participate in nest building
- Nests are built behind loose bark on dead trees or fallen logs
- Females lay 5-6 white eggs with brown speckles
- Only one brood is raised per season
- Incubation lasts 14-15 days
- Young fledge the nest at 15-17 days old
The male performs a slow, fluttering song flight to attract a mate. Once paired, the female and male work together to construct an unusual nest wedged behind loose bark up to 60 ft above ground. The female lays a clutch of 5-6 eggs which she incubates while being fed by the male. Both parents feed the nestlings regurgitated insects. Young brown creepers develop rapidly and leave the nest after just 15-17 days, able to flutter short distances.
Threats and conservation
Brown creepers face a few key threats to their populations:
- Habitat loss from forest fragmentation and logging
- Use of pesticides reduces insect prey abundance
- Severe winter weather can cause periodic declines
However, brown creeper populations appear stable across much of North America. They are listed as a species of Least Concern by the IUCN. Specific conservation actions include:
- Protecting mature forest habitats from excessive logging and fragmentation
- Allowing natural forest succession and dead tree/log retention in managed forests
- Limiting pesticide use where creepers are known to nest and forage
By protecting their forest habitat and food sources, brown creeper populations should remain secure into the future. Their inconspicuous nature keeps them under the radar of most conservation efforts.
Conclusion
In summary, brown creepers are small, inconspicuous birds that display fascinating behaviors and adaptations for life on tree trunks. Their camouflage plumage, specialized body shape, upward spiraling foraging movement, and high-pitched vocalizations make them unique. Although uncommon, they can be observed creeping along trunks and branches in mature forests across much of North America. Conserving these habitats will help ensure brown creepers remain a part of our natural heritage.