Do Birds Reuse Nests? How Long That Answer Holds

Most birds do not reuse a woven open-cup nest from a prior brood. Cavity-nesting species often reuse a nest box or a tree hole, and large raptors add sticks to the same platform for decades. The Cornell Lab of Ornithology’s All About Birds guide lists 1 to 3 broods a season for the American robin and an incubation period of 12 to 14 days, so a cup that looks empty in late May can still be an active nest in June. The U.S. Fish and Wildlife Service treats a nest with eggs, chicks, or young still dependent on it as protected under the Migratory Bird Treaty Act; an empty nest of a native migratory bird may be destroyed but not kept. The object on the property is what keeps that answer true or makes it expire.

A whip-and-tongue graft is scored in June, when the scion either pushes or dies. A nest is scored on the same delay.

How long does the reuse answer stay true?

The answer holds for one nesting cycle, which is shorter than a calendar season. Cornell’s All About Birds nesting table for the American robin records 1 to 3 broods, a clutch of 3 to 5 eggs, 12 to 14 days of incubation, and a nestling period of 13 days. NestWatch’s phenology sheet, averaging Birds of the World with Baicich and Harrison, lists the same species at 13 days of incubation and 15 days as nestlings. Those two Cornell products disagree on the nestling figure by two days.

Birds of the World reports that robin pairs generally rear 2 broods a year and sometimes 3. In Ithaca, New York, 15 percent of 27 pairs were estimated to raise 3 broods in a season.

Cliff and barn swallows stretch the clock another way. The Fish and Wildlife Service’s nuisance-swallows page states that those species often produce two clutches a year, with 3 to 5 eggs, incubation of 13 to 17 days, and fledging at 18 to 24 days, after which chicks return to the nest for several weeks.

Raptor time is measured in years. Michael N. Kochert and Karen Steenhof, in the Journal of Raptor Research in 2012, reported 45 continuous years of golden-eagle observation in southwestern Idaho: 454 nests in 66 territories, individual nests used 1 to 26 times, and gaps between reuse of 1 to 39 years. A 10-year buffer after last known use would have missed 34 percent of 300 reused nests.

Even one named bald-eagle platform refuses a round number. Birds of the World records a Vermilion, Ohio, nest used for 34 years before the tree blew down. The historical marker for the Great Nest of Brownhelm states that eagles added sticks beginning in 1891 and continuing for 35 years, until wind and rain dropped the nest on the evening of March 10, 1925. Francis H. Herrick, then professor of biology at Western Reserve University, documented that eyrie. Thirty-four and 35 years are both in print.

Which birds reuse an old nest, and which build again?

Open-cup songbirds that weave a new bowl, American robins among them, typically start over. Cornell’s All About Birds page on cleaning after fledging states that most birds do not reuse their old nests and typically build a new nest in a new location for each clutch.

Cavity nesters face a shorter menu. Anita Tendler, writing for NestWatch while at Cornell, noted that Eastern Bluebirds often build atop old material when other cavities are scarce, and that an uncleaned box can fill until the new cup sits too close to the entrance hole. Male House Wrens strip old material between clutches. A. J. Pacejka and C. F. Thompson, in the Journal of Field Ornithology in 1996, found mite counts did not drop when researchers emptied Illinois boxes.

Swallows sit between those habits. The Fish and Wildlife Service states that cliff and barn swallows may construct an entirely new nest or use old nests, building off traces of mud, and tells property managers to get rid of old nests and mud traces before spring arrival, destroying only cups that do not hold eggs or chicks.

Hummingbirds are the species asked about by name, and the clock is contested. Cornell’s All About Birds guide for the Ruby-throated Hummingbird lists 1 to 2 broods and 12 to 14 days of incubation. NestWatch’s phenology table lists the same species at an average incubation of 16 days. Twelve to 14 and 16 cannot both be the average. Kenn Kaufman and Kimberly Kaufman, field-guide authors answering a Birds & Blooms reader, wrote: “In general, the female hummingbird will build a new nest for each new brood.” They add that reuse is uncommon, though Anna’s and Allen’s hummingbirds are known to do it at times.

16 U.S.C. § 703(b) confines the Migratory Bird Treaty Act to species native to the United States or its territories. House Sparrows and European Starlings, the two species most likely to stuff a box year after year, sit outside that statute.

How does a woven songbird nest compare with a nest box?

A robin’s mud cup, a bluebird box, and an eagle platform do not share a reuse rule, a cleaning rule, or a permit rule.

| | Woven open-cup (robin) | Managed nest box | Stick platform (eagle) | |---|---|---|---| | Typical reuse | New cup each clutch | Same box, same season or later years | Same nest, added to for decades | | Clock | Cornell: 1–3 broods; 12–14 days incubation | NestWatch bluebird: 14 days incubation, 17 nestling days | Kochert and Steenhof: 1–26 uses, 45 years | | After young leave | Leave the cup | Material may stay for a second brood | Still an eagle nest when empty | | Empty-nest law | Destroy, do not keep, once inactive | Same for the lining | Permit required at all times |

Jimena López-Arrabé and colleagues, in Ardeola in 2012, offered Pied Flycatchers in central Spain both boxes with old material and cleaned boxes. Occupation was 53.97 percent for new nests and 56.76 percent for reused nests. Ectoparasites were present in all studied nests: mites and fleas in 54 nests (98.2 percent) and blowflies in 21 nests (38.2 percent). Blowfly and flea counts were higher in old nests; mite counts were not.

When is it legal to take down an abandoned nest?

16 U.S.C. § 703 makes it unlawful, except as permitted by regulation, to take or possess any migratory bird, or any part, nest, or egg of such a bird. The Fish and Wildlife Service’s bird-nests page restates the working line: it is illegal to destroy a nest that has eggs or chicks in it, or if young birds are still dependent on the nest, and illegal to keep a nest taken from a tree or found on the ground without a permit.

The same page draws a second line. The Act does not prohibit destruction of a bird nest alone, without eggs or birds in it, provided that no possession occurs during destruction. The Service usually requires waiting until the nest is inactive (no eggs, no chicks, no longer in use for breeding) before destroying it. Permits to take an active nest are issued only in limited cases, typically human health or safety. On swallows, the Service states that inactive (empty) nests do not require a permit to destroy, and that it does not issue permits for bird nuisance issues.

The penalty range for an ordinary violation sits in 16 U.S.C. § 707(a): a misdemeanor, a fine of not more than $15,000, imprisonment of not more than six months, or both. Section 707(b) sets a felony for sale or take-with-intent-to-sell: a fine of not more than $2,000, imprisonment of not more than two years, or both.

Eagle nests are a different statute and stay protected when empty. The Service’s Bald and Golden Eagle Protection Act page states that a first offense can bring a fine of $100,000 ($200,000 for organizations), imprisonment for one year, or both, with a second violation a felony. 16 U.S.C. § 668(a) still prints a first-offense criminal fine of not more than $5,000 and imprisonment of not more than one year, and $10,000 and two years for a later conviction after October 23, 1972. The Service’s $100,000 figure tracks the alternative-fine schedule in 18 U.S.C. § 3571. Title 16 and the Service page do not print the same dollar amount.

An abandoned nest reused by a later pair is still a nest. NestWatch tells monitors that if a clutch is suspected not to hatch, wait four weeks past the expected hatch date before removing eggs, because monitors have reported “abandoned” nests that later hatched.

When should a nest box be cleaned after the birds leave?

NestWatch’s FAQ after fledging says that during the breeding season, nesting material should stay in the box because the parents may raise another brood. At the end of the season, the material can come out and the interior can be scrubbed with a mild detergent and water. If the nest is soiled with feces, NestWatch recommends a solution of 1 part bleach to 10 parts water. Some monitors clean after every brood, and only when there is absolutely no sign of breeding activity. A companion NestWatch FAQ adds that waiting until fall is also accepted.

Robyn Bailey, NestWatch Project Leader at the Cornell Lab of Ornithology, told a reader who asked whether emptying and washing were both required: “Simply emptying it of nest materials.”

Whether cleaning helps occupancy is a split NestWatch itself cites. M. T. Stanback and A. A. Dervan, in The Auk in 2001, used 100 nest boxes in North Carolina. After a successful first clutch, they cleaned half. When Eastern Bluebirds had a choice, 71 percent moved to a clean box. W. H. Davis, P. J. Kalisz, and R. J. Wells, in the Journal of Field Ornithology in 1994, found that Eastern Bluebirds in Kentucky preferred boxes that still held old nests. NestWatch reports that parasitic wasps there kill blowfly pupae over the winter, so pulling the old nest can interrupt a control insect. Those two results do not average into one national cleaning date.

1. Confirm the nest is inactive: no viable eggs, no live young, no fledglings still returning to the cavity.
2. Identify the occupant. A House Sparrow or European Starling lining is not a Migratory Bird Treaty Act nest. A swallow, bluebird, or wren lining is. An eagle stick nest is never a box-cleaning job.
3. If a second brood is still possible, leave the material. If the local season is over, remove the lining and scrub with mild detergent and water, or with the 1-to-10 bleach wash if feces are present. NestWatch forbids pesticides in boxes because residue remains.

What happens to old nests if they stay put?

A woven cup in a shrub weathers. Cornell’s All About Birds cleaning note is the default for those nests: leave them. Pulling them does not create a cleaner nursery for the same pair.

A box that keeps last year’s lining keeps last year’s arthropods. López-Arrabé’s 98.2 percent mite-and-flea prevalence and 38.2 percent blowfly prevalence were measured in nest boxes, the habitat where old material actually persists. NestWatch says leftover material also makes a home for mice, and that mouse nests should come out in spring, with gloves and a dust mask.

Swallow mud that stays on an eave is an invitation. The Fish and Wildlife Service says swallows reuse old nests and build from remaining mud. Scraping an empty cup off before spring migration is how that reuse is interrupted.

An eagle platform that stays put is doing the job it was built for. Kochert and Steenhof’s 39-year gap still does not authorize removal.

FAQ

Do birds reuse old nests from last year?

Some cavity nesters and raptors do; most open-cup songbirds do not. Cornell’s All About Birds states that most birds build a new nest in a new location for each clutch. Golden eagles in Kochert and Steenhof’s 45-year Idaho study reused individual nests 1 to 26 times. The structure in the yard decides.

Can I take down an abandoned nest on my porch?

Once the nest is inactive, with no eggs and no live young, the Fish and Wildlife Service says a native migratory-bird nest may be destroyed but not kept. Active nests require a permit. Eagle nests need a permit even when empty. House Sparrow and starling nests sit outside the Act.

Do hummingbirds reuse nests?

Cornell lists 1 to 2 broods for the Ruby-throated Hummingbird and 12 to 14 days of incubation; NestWatch lists 16 days as the average, so those two Cornell products disagree. Kenn and Kimberly Kaufman write that the female typically builds a new nest for each brood.

When should I clean a nest box after the birds leave?

After the box is inactive. NestWatch tells monitors to leave material during the breeding season, then empty it at season’s end and scrub with mild detergent, or with 1 part bleach to 10 parts water if feces are present. Cleaning after every brood is allowed only with no sign of activity. Waiting until fall is also accepted.

Will the same birds come back to last year’s nest?

Cavity nesters often return to the same box. Open-cup songbirds usually build a new cup, sometimes nearby. The Fish and Wildlife Service states that cliff and barn swallows reuse old mud nests or build from remaining traces, which is why empty cups should come down before spring arrival.

What happens to old bird nests if nobody removes them?

Woven cups fall apart and are seldom reused. Boxes keep parasites and can attract mice; López-Arrabé and colleagues found mites or fleas in 98.2 percent of Pied Flycatcher boxes and blowflies in 38.2 percent. Swallow mud left on an eave is likely to be reused. Eagle stick nests remain protected platforms.