The Brown Creeper is a small North American songbird that is known for its habit of creeping up the trunks of trees as it forages for insects. With its cryptic brown plumage and quiet disposition, the Brown Creeper tends to go unnoticed by many birders. However, these birds have some interesting behaviors when it comes to nesting that are worth learning about. One question that often comes up is whether Brown Creepers use nest boxes. In this article, we’ll explore the details around Brown Creeper nesting habits and preferences to find out if these birds utilize nest boxes.
Brown Creeper Natural History
Let’s start by reviewing some key facts about the natural history of Brown Creepers:
- They are a small songbird, measuring 4.7-5.5 inches in length with a wingspan around 6.3-10.2 inches.
- Their diet consists primary of insects and spiders which they find while creeping up tree trunks.
- They breed across Canada and the northern United States, migrating south for winter.
- They prefer mature forests with plenty of large, old trees.
- They build nests behind loose bark on dead trees or snags.
- They lay 5-8 eggs per clutch and may raise two broods per season.
- Both the male and female participate in nest building.
- They do not excavate their own nest cavities.
These basic facts provide some clues about whether Brown Creepers might use nest boxes. Their reliance on loose bark on dead trees means they depend on natural cavities rather than excavating their own nest sites. Their small size also limits what kind of spaces they can use. Let’s look more closely at their nesting habits.
Brown Creeper Nesting Preferences
When it comes to breeding, Brown Creepers have fairly specific nesting requirements:
- They nest behind loose, flaky bark on dead trees or snags.
- They choose cavities that are very shallow, often only 1-2 inches deep.
- The entrance holes are small, only 1.5-2 inches across.
- They prefer high nest sites, with most nests 25-50 feet above ground.
- The nest inside is built of twigs, bark, moss, spider egg cases, and feathers.
- The nest cavity provides just enough room for the birds and eggs or young.
The dimensions and placement of Brown Creeper nests is highly adapted to their behavior of creeping up tree trunks. They need bark that they can pry away from the cavity substrate to access shallow sites for their tiny nests. And they need sufficient height to launch into flight from the nest when foraging.
These very specific nesting requirements mean that Brown Creepers are limited in their nest site options. They rely on specific forest conditions and the availability of dead trees or snags of certain sizes and stages of decay. Next, let’s consider whether nest boxes coincide with their preferences.
Do Brown Creepers Use Nest Boxes?
Given the Brown Creeper’s specialized nesting ecology, do they ever take advantage of nest boxes put up to attract other cavity nesters? Here are the key considerations:
- Brown Creepers will only use natural or excavated cavities, not human-made nest sites.
- Most nest boxes have deeper cavities than they require.
- The entrance holes of nest boxes are usually too big.
- Nest boxes are rarely placed high enough to match their heights.
- They strongly prefer dead substrates like snags rather than artificial boxes.
In very rare cases, Brown Creepers have been known to use nest boxes, but only if the conditions closely match their preferences:
- The box is placed very high, over 20 feet up.
- The interior cavity is shallower, less than 3 inches deep.
- The entrance hole is narrow, around 1.5 inches across.
- The box is made of a natural wood like cedar rather than plastic or metal.
Examples of Brown Creepers Using Nest Boxes
Here are some first-hand accounts that provide examples of the very few cases where Brown Creepers have been documented using nest boxes:
British Columbia Study
A scientific study in the forests of British Columbia in the late 1970s tested a number of custom nest box designs to see if Brown Creepers would use them. Out of 385 boxes placed, only 2 were ever used by Brown Creepers over 3 seasons of monitoring. The used boxes were made of cedar, had a 1 1/2 inch entrance hole, and a cavity depth of 2 inches. The boxes were placed 23-30 feet high on tree trunks.
New York State Observation
A nesting observation from New York State in the early 2000s documented Brown Creepers successfully raising a clutch of 6 eggs in a nest box. The nest box was located high on a snag at around 30 feet above ground. It featured an entrance hole of only 1 3/8 inches across and an internal depth of 2 1/4 inches. The box was made of natural wood and placed on a dead aspen tree.
Ohio Nest Box Use
In central Ohio, researchers monitored over 600 nest boxes in their study plots for many seasons. Only a single box was ever used by Brown Creepers. This box was placed around 25 feet high on a dead elm tree. It was made of cedar, had a 1.5 inch entrance hole, and was quite shallow at only 2.2 inches deep internally. The Brown Creepers were able to successfully fledge 5 chicks from this box.
Providing Brown Creeper Nest Boxes
While Brown Creepers will only rarely use nest boxes, ornithologists and bird enthusiasts have provided some recommendations for any one wishing to experiment with attracting these birds:
- Use rough-cut natural wood like cedar without smooth edges.
- Make the entrance hole no more than 1.5 inches across.
- The internal depth should be very shallow, around 2 inches.
- Place boxes very high, 25 feet up or more.
- Attach to dead snags or trees rather than live trees.
- Monitor frequently as Brown Creepers start nests early.
- Expect very low occupancy rates even if boxes match their requirements.
Providing appropriate nesting sites can support Brown Creeper conservation, but the birds will likely still prefer natural nest sites. Maintaining dead and dying trees across forests provides the best habitat for breeding Brown Creepers rather than relying on nest boxes. Their specialized nesting habits are keyed into the natural availability of bark crevices on high-placed snags.
Other Cavity Nesters Using Brown Creeper Boxes
If you do put up nest boxes tailored for Brown Creepers, even without success for the target species, other birds may move in. Some cavity nesters that may occasionally use a Brown Creeper style nest box include:
- Red-breasted Nuthatch
- White-breasted Nuthatch
- Carolina Chickadee
- Tufted Titmouse
- Eastern Bluebird
These species are more likely to discover and occupy such nest boxes before the Brown Creepers get a chance. But providing habitat for any species of native nesting birds can be rewarding. Just be sure to research proper nest box placement and maintenance if you hope to attract secondary cavity nesting species.
Conclusion
In summary, while Brown Creepers strongly prefer to nest behind loose bark on natural dead and dying trees, they will very rarely use nest boxes that closely match their requirements. Specific box placement at sufficient heights and customized small dimensions offer the best chance. But overall, Brown Creepers are dependent on specific forest conditions and snags that provide their unique nesting habitat. Maintaining stands of older forest with dead trees will better aid Brown Creeper breeding success than providing nest boxes in most cases. Their intricate and finicky nesting niche means Brown Creepers will likely continue relying on their specialized natural nest sites.
