Tag Archives: cornell

Barn Swallows

Not in my yard. Sadly, this is cheating in the sense that it doesn’t have any place in my Back Yard project. But there are 6 or 7 nests in my “weekday” yard (a nearby building on the UNM campus.)

There are swallows nesting under the eaves of a huge cement building. I’ve been watching them casually. Hirundo rustica. I wanted to know:
*Do they mate for life?
*How long they live?
*Do they migrate (if so where, and for how long)?
*And do they tend to return to the same nest?

Cornell’s All About Birds says:

  • they weigh about 6 ounces.
  • they are 6-7″ in size.
  • the sexes look similar: males are darker chestnut underneath and have longer tail streamers. (apparently the girls like boys with long symmetrical tails & darker red chests)
  • “Tail length appears to be reliable signal of individual quality in both males and females.” A good indicator of all around health & well-being. wow.
  • originally a cave breeder, they are now almost exclusively urban dwellers.
  • they winter throughout South America
  • require mud for nest-building
  • eat insects caught while flying, mostly low to the ground
  • 3-7 eggs: creamy white with small dark spots
  • When the weather is really cold, they huddle in bunches, sometimes with other kinds of swallows.
  • They tend to be monogamous, though at times males will take a second wife (while devoting most of his parental attention to offspring by his first mate).
  • They sunbathe. (no kidding!)
  • And they are one of the most thoroughly researched birds in the western hemisphere. Their range is everywhere EXCEPT Florida and a tiny snip of southern California. (So that is why they are not familiar to me).
  • [Birds of NA- Breeding] No systematic differences in compass directions in which nests are oriented.
  • [ditto] Both sexes nest build, but the females are dominant, especially in shaping. If they reuse a nest from the previous year, they check it for parasites, toss out the old feathers, and add new mud. Refurbishing takes ~5 days. Building from scratch ~11. And they tend to remodel between broods in the summer (some new mud and new feathers) “if it is reused within a season.” Oh… and they do steal nest-lining materials when they can get away with it. Evidence is really mixed about the extent to which they return to the same nest year after year, since they sometimes choose a different nest between clutches in a single summer.

They migrate in early spring. Spend a couple of weeks dating if they aren’t already paired up. Then spend a week or so honeymooning and building up their strength, then select a nest or nest site and start building or refurbishing a nest. That takes a week or two. Then they generally have a couple of days of quiet after they have finished the babys’ room before laying eggs. The female lays one egg per day, often in early morning. 3-7 total. Even within colonies, this appears to be asynchronous.

They start incubating after the last egg, or if there are going to be tons– after number 5. Both male and female help out, though the female does the lion’s share. They can leave the nest more the warmer it is… And if they have tons of feathers to insulate the nest, they have to spend less time on it. “Nest attentiveness” . They roll the eggs with their bills at the start of an incubation bout. Females spend the night on the nest. And have to get their own food the whole time.

Eggs hatch in roughly 24-hours. Naked at birth, eyes closed. Takes ~19 days to fledge. Their eyes open gradually days 5-8, and they start growing feathers at days 4-8. They really aren’t homeothermic until ~ day 10.

Nestlings begin flapping wings by day 9, begin preening by days 12–15 by drawing open bill along feather-shafts to remove pieces of white feather-sheaths, and stand on nest rim by day 14 (Smith 1933, Wood 1937, Tabler 1956). Starts to show fear response by day 9, retreating from nest rim and hunkering down at alarm call of adult (Smith 1933). May fledge prematurely by day 14 if handled (Anthony and Ely 1976).

Evidence suggests that older parents do a better job of feeding their brood than newbies. Babies turn around and poop over the edge after eating, so that seems to give everyone a chance at being fed. ((Females seem to work a bit harder at carrying back the groceries.)) “Female parents lose mass steadily while feeding young (up to 19.3% of body mass); male parents show no consistent pattern (Jones 1987a).”

As with crows, there appear to be some “helping.” Unattached males, young females … with varying motives. Juveniles from the 1st brood often help feed the 2nd.

After 15-24 days they are ready to leave the nest.

Association With Parents Or Other Young

Parents lead young back to nest to sleep for up to several days after fledging. Broods in Washington traveled mean of 0.48 km (n = 11) from nest site, where they usually stayed in same general area for several days, often perching on wires or other exposed perches; broods typically remain segregated from others, and juveniles do not mix between broods until independent (no creches form; Medvin and Beecher 1986). Parents do not recognize their own young (Grzybowski 1979) and thus do not discriminate against conspecific juveniles if any join the brood.  (emphasis mine)

Ability To Get Around, Feed, And Care For Self

Juveniles are fed by their parents for several days, possibly up to a week, after fledging; family groups have broken up entirely by 2 wk after fledging (Smith 1937, Medvin and Beecher 1986). At first juveniles are usually fed while perched, but eventually they begin taking food from their parents in flight, flying to meet incoming adult, and food is transferred in midair.

Not a lot of definitive studies re. how long they live (isn’t that interesting?!)  ~ 8 years?

Parasites:  fleas.  mites. blowflies.  (Mites have a negative impact on reproduction and quality of life.)
Mortality:  Exposure exacts a huge toll.  Cold rainy weather late spring/ early summer.  Extreme heat in the summer. Cold rainy weather on their wintering range.  Drought reducing insect food supplies…
Significant competition with House Sparrows (pushing them out of desirable nesting areas).

Young seldom return to their birthplace.

They are roughly a year old before they start breeding.

Once they are adults, 20-35% return to the same spot (“Fidelity to Breeding Site”).  Out of that group 15-30% reuse the same nest.  So the answer to my question is, not really.  Certainly not religiously.

Home Range

In Pennsylvania, 96 birds were transported 16–96 km from their nests and released; 55% of birds returned to their nests (Nastase 1982). Distance and direction from nest site did not significantly affect homing ability, at least within 100 km. Studies in Europe over longer distances (up to 1,875 km) show that homing ability declines with distance from nest site; birds released up to 153 km away returned the same day, and maximum speed of return was 412 km/d (reviewed in Nastase 1982). Birds in W. Virginia foraged within 1.2 km of nest site (Samuel 1971a); those in Europe generally confine their foraging to radius of 500 m from nest site (Møller 1987a).  They stay pretty close to the nest.

Population Regulation – probably based on weather (cold) more than availability of suitable nesting sites.

Citation for Birds of North America Online:
Brown, Charles R. and Mary Bomberger Brown. 1999. Barn Swallow (Hirundo rustica), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/452 (General citation for what’s below)


The Barn Swallow’s close association with human habitations means that it is well known to the public, and in some parts of the world having Barn Swallows nest on one’s property is considered a harbinger of good luck. Legend has it that the Barn Swallow consoled Christ on the cross and got its forked tail because it stole fire from the gods to bring to people, losing its middle tail-feathers when a wrathful deity hurled a firebrand at it (Turner 1991). Another superstition is that cows will give bloody milk or go dry if anything happens to the Barn Swallows nesting on a farm. Barn Swallows have been closely associated with humans and their structures for more than 2,000 years in Europe (Møller 1994a).

As a consequence of both its wide distribution and its nesting on accessible artificial structures near people, the Barn Swallow has been studied extensively throughout the world and especially in Europe. More papers have been published on this species than on any other swallow, and it is one of the most thoroughly studied birds in the world. The Barn Swallow has figured prominently in studies on the costs and benefits of group living (Snapp 1976, Møller 1987a, Shields and Crook 1987), and it has served as a model organism for detailed studies on the mechanisms of sexual selection (Møller 1994a).

“Legend has it” that the Barn Swallow “stole fire from the gods to bring to people, losing its middle tail-feathers when a wrathful deity hurled a firebrand at it (Turner 1991).” They have been nesting in and around human dwellings for nearly 2000 years in Europe, and perhaps partly because of this, they are one of the “most thoroughly studied birds in the world.”

Barn Swallows “—not the more famous egrets—have the distinction of having indirectly led to the founding of the conservation movement in the United States: the destruction of Barn Swallows for the millinery trade apparently prompted George Bird Grinnell’s 1886 editorial in Forest and Stream that led to the founding of the first Audubon Society (G. Gladden in Pearson 1923).”


wow. sunbathing. “perching substrate.” and finding a place to hide and hang on during high winds:

Walking, Hopping, Climbing, Etc

When on ground, walks exclusively. Goes to ground only to collect mud, grass, or feathers for nest, to pick up bits of gravel or (rarely) moribund insects, to sunbathe, or to seek refuge from strong winds. Sidles along a wire, tree branch, or other perching substrate using a sideways walk.


….. Long tails, along with high levels of symmetry in wing and outer tail, may improve foraging efficiency during extreme weather conditions (Brown and Brown 1999). Glides rarely…. (Blake 1948). Carries tail nearly closed, except when turning or braking on landing. Flight speed is not much greater than that of other swallows, but with straighter flight this species covers ground more rapidly (see Blake 1948). Speed estimated at 8.0 m/s ± 2.0 SD (range 5–17), which matches the speed predicted if birds were flying to maximize rate of food delivery to nestlings (de la Cueva and Blake 1997).

Swimming. Only it if falls in somewhere by accident. Flaps like hell until it can climb out. “No diving.” grin.

Self-Maintenance / Preening, Head-Scratching, Stretching, Bathing, Anting, Etc

From Møller 1991e, except as noted. Usually preens at perch sites near nest; preening peaks in early morning and evening and consists of quick movements through feathers, especially of wing and tail, ending with bird’s shaking entire body. Only about 3.1% of preening bouts involve contact with uropygial gland. Total time spent preening varies among individuals (0–14.6%); nestlings preen more when their nests are infested by mites, but there was no such effect for adults. Preening declines during breeding cycle. Scratches head over wing. Stretches by extending one wing at a time below feet; then extends both in a V over back. This stretching sequence often immediately precedes flight. Yawns sometimes accompany stretches. Bathes by skimming water surface and “hitting” surface briefly in violent collision, sometimes several times in succession. In heavy rain, points bill straight up and holds position without moving. Birds in Europe seen dust-bathing in cinders, rolling and flapping wings in same manner as House Sparrows do (Tubbs 1954). Anting not known to occur.

That’s great. Yawning & stretching. “Anting”?! Using the heavy rains to bathe, beak up/ eyes closed?

Sleeping, Roosting, Sunbathing

Pairs often sleep together in nest or on rim, or on adjacent part of structure (e.g., nearby beam), for much of breeding season, but will begin roosting elsewhere by the time young approach fledging (Smith 1937).

Prior to migrating they often gather in huge groups.

They are known to sunbathe. No kidding. Often on hot days, using metal roofing to intensify the heat. We really don’t know why. (Maybe killing parasites.) “may aid in ectoparasite control.”

Daily Time Budget

Little information for North American race. For adult H. r. rustica in Britain dur-ing brood-rearing period, 33.3% of birds’ time was spent roosting, 15.8% resting, and 50.9% flying (foraging; Turner 1983).

Isn’t that great!! Scavenging for food. Sitting on the nest. And resting just a bit.

Pair Bond

Most birds establish pair bonds after arrival on breeding grounds. Pairs form anew each season, but members of a pair often remain together for 2 consecutive seasons if successful the first season (Shields 1984b).

While she is fertile, her mate may guard her by following her around (to prevent another unattached male from mating with her).

During migration and winter, they roost in huge flocks, separating during the day to forage. Helps them defend themselves against predators.

Interestingly though, parents do not appear to recognize their young. Brids do not appear to choose colony life, but tolerate each other because the most suitable nesting sites force them into it. [Hmm. As with humans? There may be a net reproductive cost to living in colonies. Some mixed evidence on this.]:

In H. r. rustica in Denmark, costs of coloniality were more obvious than benefits: birds nesting in larger colonies found less food, experienced more extra-pair copulations, more ectoparasitism, more predation, more infanticide, and more brood parasitism, and spent more time guarding their mates and nests (Møller 1987a).

Nonpredatory Interspecific Interactions

Eastern (Sayornis phoebe) and Say’s (S. saya) phoebes, Cliff and Cave swallows, House Wrens (Troglodytes aedon), House Sparrows, and Myotis bats usurp Barn Swallow nests, sometimes destroying eggs in the process; Cliff Swallows create dome over nest with mud to make characteristic jug shape, and sparrows fill interior with grass. Cliff Swallows (and probably Cave Swallows) are dominant over Barn Swallows in nest-site interactions, and in mixed colonies Barn Swallows often occupy only the darkest interiors of culverts, which Cliff Swallows seem to like least (Brown and Brown 1996). House Sparrows destroy Barn Swallow eggs and nestlings in nest takeovers and steal nesting material from Barn Swallows (Weisheit and Creighton 1989). Pair of Barn Swallows and pair of Say’s Phoebes occupied same nest in New Mexico; both species laid eggs, incubated, fed each other’s nestlings, and eventually fledged young (Kozma and Mathews 1995). Each exhibited aggression toward each other upon encounters at nest. Birds occasionally build nests adjacent to wasp nests (see Breeding: nest site, below), but they do not seem to interact obviously with the wasps (Jackson and Burchfield 1975).

Nest thieves–ack! And it sounds like the barn swallows are at the bottom of the Swallow pecking order. (You guys can have the dark corners, the spots we don’t like…) May nest near wasps, but both creatures leave the other alone. How interesting!


Eek. Grackles chase adults in mid-air, or sometimes attack them on the ground when they think they can get them.

They are most assertive when defending nestlings. (They mob together in small clumps: 1-19) Parents take the high risk dives.

Heavens. There is an entire (long) page on Breeding. They tend to arrive the end of May. Over the course of roughly a month, they choose a partner, honeymoon, nest-build, watch videos, do a little jogging, some shopping, & initiate a clutch. “First Brood Per Season”. Late July, early August, “Second Brood Per Season.” Both help nest build, with the females ‘taking a more active role.’ New nests take 1-2 wks to construct, depending on weather, etc.

Reusing nests takes about half that long. They throw out old feathers and some of the old mud & add new. Wow. Someone counted: nests may contain 750-1400. mud pellets!!

OK. I’m stopping to go home. I was just really getting started on the Breeding article: http://bna.birds.cornell.edu/bna/species/452/articles/breeding