Of the swallow family, Hirundinidae, the migratory barn swallow is the most distributed species located worldwide (Scordato & Safran, 2014).  “The population dynamics of migratory birds are influenced by both the local weather and large-scale patterns in climate that can operate at various stages of their annual cycle” (García-Pérez, Hobson, Albrecht, Cadman, & Salvadori, 2014). Based on the conditions and choose of wintering sites, barn swallows have the innate ability to perceive the appropriate timing of when to start the spring migration to their desired nesting location (Pancerasa, Ambrosini, Saino, & Casagrandi, 2018).  The continent-wide migration is divided into two migratory regions, the western regions and eastern regions. The western region has wintering area from Oregon to northern Colombia with the nesting range stretching from Washington to Saskatchewan, Canada. The eastern regions has wintering areas from South America to the Amazon Basin with nesting grounds in Ontario and New Brunswick, Canada (Hobson et al., 2015).

They range from sea level up to 10,000 feet. Their breeding habitats must have cliffs or human structures with eaves and rafters for them to construct nests on. The barn swallows nests are made of mud, formed in a partial bowl shape. Available sources to build the nest needs to be close by so locations near water or fields are ideal. Swallows also benefit from an agricultural setting because the insects that surround livestock can be an excellent food source for these aerial insectivores (Scordato & Safran, 2014). The male barn swallow becomes territorial defending the best nesting sites from the previous year. Nest used in the previous year’s saves time and energy but has an impact on the mortality rate of the newly hatched chicks. This is due to parasitic infestation and degradation of old nests (Hasegawa, Arai, Watanabe, & Nakamura, 2011; Shields and Crook 1987; Moller 1990). “The parasites (hematophagous mites) are common in old nests that had been used in previous years and significantly reduced chick survival” (Barclay, 1988). Studies have concluded that there is no significant impact on the birth rate of adult barn swallows using old or new nests (Barclay, 1988).

Photo By: Muttergluck

Barn swallows being an insectivorous passerine, forage in open areas from parks, agricultural fields, beaches, and over open water. Their diets consist majority of flies and other flying insects. “Barn swallows selected strongly for insects in the order Hymenoptera (mainly Formicidae, which comprised 29% of diet), and selected against insects in the orders Coleoptera, Diptera, and Lepidoptera” (Law, et al., 2017). They take one relatively large insects at a time then feed on a swarm of insects. “The presence of domestics animals increases the amount of larger prey (mainly larger Diptera and Coleoptera) and decreases the proportion of smaller prey (Hymenoptera species)” (Orłowski & Karg, 2013). Like many different types of birds the barn swallow will pick up small pebbles, egg shells or oyster shells to help break down the insects in there gizzard and absorb calcium (Brown & Brown, 1999).

The barn swallow’s song is a “twitter-warble” followed by a few “whirrs” which can last for 4-20 seconds at a time. The two main calls of the barn swallow that are used when threatened are a “cheep” when there is a threat and a “churee” whistle when they dive toward the  threat (All about birds, 2017).

Here is a sound clip of a barn swallow singing.

Song By: Steve Hampton

Barn swallows are a monogamous species. Females choose a mate for each season. Females alone incubate the clutch which range from two to seven eggs, and can produce one to three clutches per breeding season (Saino et al., 2002). The mate choosing of a female choosing a male facilitates sexual selection by promoting male on male competition and indirect mate choice (Hasegawa, et al, 2011). “Sexual selection (i.e., any phenotypic variation nonrandomly related to variation in mating success) often explains the presence of apparently nonadaptive traits in many animal species” (Darwin, 1871). An unmated male barn swallow may kill the nestlings of a nesting pair. The actions of this unmated male often succeeds in breaking up the pair and allows him the opportunity to mate with the female (Brown, 1999).

“Females are known to prefer males with long outermost tail feathers as social as well as extra-pair mates” (Moller 1994, Saino, et al., 2002). The trait of overly elongated external tail feathers on a female barn swallow is not an ideal trait. At the beginning of a breeding season females with longer tails, will produced less offspring during the following breeding season compared to female barn swallows with shortened or unmanipulated tails. This finding could be one reason why the tail feathers on female barn swallows are not as long as those of male barn swallows. (Cuervo, 2003). “A classic example of a sexually selected trait, the deep fork tail of the barn swallow, Hirundo rustica, is now claimed to have evolved and be maintained mainly via aerodynamic advantage rather than sexually selected advantage” (Hasegawa, Arai, & Kutsukake, 2016).

A sexually desired trait of the barn swallows, like many other birds, is the color of the plumage. It has been concluded in a study that the darker ventral coloration of the feathers is linked to the increased reproductive success in male barns swallows. “Thus parents tune their efforts toward more valuable invest in offspring that are likely to provide the greatest fitness returns” (Romano et al., 2016).

The barn swallow need to ingest carotenoids in their diets to aide in various colors (red, orange and bright yellows) presented in the feathers. The carotenoids are extracted exclusively from the grains, seeds or vegetable matter that is found in the barn swallows diet. The amount of carotenoids that is passed to the developing eggs can affect the growth and development of immunity of the mother’s off-springs. “Females may thus transfer carotenoids to the eggs differentially in relation to the reproductive value of the offspring as affected by sexual ornamentation of their father” (Saino, et al., 2002).

Photo By: FishHawk

Conservation of migratory birds can be a challenge. As of now there are no conservation issues with the barn swallow, but their population numbers are dropping. This drop in population is from the change in their breeding and wintering grounds, from the change in land use, agricultural intensification and increased pesticide uses (Hobson et.al, 2015). “One study found that the annual survival rates of Barn Swallows breeding in Seattle, WA were higher in years preceded by El Nino Southern Oscillation (ENSO) winters and high in years with more positive North Atlantic Oscillation (NAO) values” (Garcia-Perez, et al., 2014). The graph below represents data collected from the Audubon Christmas bird counts on the barn swallow.

Created By: Trishia Heltemes, Data from Audubon Christmas Tree Counts http://netapp.audubon.org/CBCObservation/Historical/ResultsBySpecies.aspx?1

Barclay, R. (1988). Variation in the Costs, Benefits, and Frequency of Nest Reuse by Barn Swallows (Hirundo rustica). The Auk: Ornithological Advances, 105 (1), 53-60. https://doi.org/10.1093/auk/105.1.53

Barn Swallow Sounds, All About Birds, Cornell Lab of Ornithology. (2017). Retrieved March 01, 2019, from https://www.allaboutbirds.org/guide/Barn_Swallow/sounds

Brown, C. R., & Brown, M. B., (1999). Barn Swallow (Hirundo rustica), version 1.0. In The Birds of North America (A. F. Poole and F. B. Gill, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bna.452

Cuervo, J. J. (2003). Experimental manipulation of tail length in female barn swallows (Hirundo rustica) affects their future reproductive success. Behavioral Ecology, 14(4), 451-456. doi:10.1093/beheco/arg027

Darwin C, 1871. The descent of man, and selection in relation to sex. London: John Murray.

García-Pérez, B., Hobson, K. A., Albrecht, G., Cadman, M. D., & Salvadori, A. (2014). Influence of climate on annual survival of Barn Swallows (Hirundo rustica) breeding in North America. The Auk, 131(3), 351-362. doi:10.1642/auk-13-145.1

Hasegawa, M., Arai, E., & Kutsukake, N. (2016). Evolution of tail fork depth in genusHirundo. Ecology and Evolution, 6(3), 851-858. doi:10.1002/ece3.1949

Hasegawa, M., Arai, E., Watanabe, M., & Nakamura, M. (2011). Female mate choice based on territory quality in barn swallows. Journal of Ethology, 30(1), 143-150. doi:10.1007/s10164-011-0307-8

Hobson, K. A., Kardynal, K. J., Wilgenburg, S. L., Albrecht, G., Salvadori, A., Cadman, M. D., . . . Fox, J. W. (2015). Correction: A Continent-Wide Migratory Divide in North American Breeding Barn Swallows (Hirundo rustica). Plos One, 10(7). doi:10.1371/journal.pone.0133104

Law, A. A., Threlfall, M. E., Tijman, B. A., Anderson, E. M., Mccann, S., Searing, G., & Bradbeer, D. (2017). Diet and Prey Selection of Barn Swallows (Hirundo rustica) at Vancouver International Airport. The Canadian Field-Naturalist, 131(1), 26. doi:10.22621/cfn.v131i1.1777

Orłowski, G., & Karg, J. (2013). Partitioning the effects of livestock farming on the diet of an aerial insectivorous passerine, the Barn SwallowHirundo rustica. Bird Study, 60(1), 111-123. doi:10.1080/00063657.2012.748717

Pancerasa, M., Ambrosini, R., Saino, N., & Casagrandi, R. (2018). Barn swallows long-distance migration occurs between significantly temperature-correlated areas. Scientific Reports, 8(1). doi:10.1038/s41598-018-30849-0

Romano, A., Bazzi, G., Caprioli, M., Corti, M., Costanzo, A., Rubolini, D., & Saino, N. (2016). Nestling sex and plumage color predict food allocation by barn swallow parents. Behavioral Ecology, 27(4), 1198-1205. doi:10.1093/beheco/arw040

Saino, N., Bertacche, V., Ferrari, R. P., Martinelli, R., Møller, A. P., & Stradi, R. (2002). Carotenoid concentration in barn swallow eggs is influenced by laying order, maternal infection and paternal ornamentation. Proceedings of the Royal Society of London. Series B: Biological Sciences,269(1501), 1729-1733. doi:10.1098/rspb.2002.2088

Scordato, E. S., & Safran, R. J. (2014). Geographic variation in sexual selection and implications for speciation in the Barn Swallow. Avian Research, 5(1). doi:10.1186/s40657-014-0008-4

Sibley, D. (2016). Sibley birds west: Field guide to birds of western North America. New York: Alfred A. Knopf.

Hi, my name is Trishia Heltemes. I am creating this blog for my last class at The Evergreen State College, Birds inside and out winter 2019 this will complete my bachelor’s in science degree. Hoping that I’ll be able to pursue a future career in the environmental field. Being outdoors is my favorite place to be if its from riding my horses, hunting/fishing, or just hiking. Helping preserve the outdoors is a passion and I want future generations to be able to experience it the same way or better than it is now.