My runs around Davis lately have been peppered by high-pitched, double-syllabic calls emerging from treetops and house roofs. They come from black phoebes, handsome little flycatchers that are keeping an eye on their suburban territories.
If you're a gardener or farmer- these little guys should be on your radar. They are insectivores: ravenous consumers of pest insects galore. On the wing, they are acrobatic hunters- taking out flying insects and gleaning from leaves and plants.
If you're a gardener or farmer- these little guys should be on your radar. They are insectivores: ravenous consumers of pest insects galore. On the wing, they are acrobatic hunters- taking out flying insects and gleaning from leaves and plants.
According to the National Audubon Society, the phoebes (a group of tyrant flycatchers including the Eastern-, Black-, and Say's- Phoebes) are named for their call: which sounds like they are repeatedly saying 'Phee-bee'. I wonder though, if their name comes in part from the Greek Titan Phoebe; who was associated with the moon and was grandmother of the great hunter Artemis. The grey, black and white color palette and hunting prowess of these elegant tyrants certainly seems to match the vibe of those Greek super-powers.
There are 3 species of phoebe in the US- the black phoebe, the Say's phoebe, and the eastern phoebe:
There are 3 species of phoebe in the US- the black phoebe, the Say's phoebe, and the eastern phoebe:
Phoebes are sit and wait predators: they hunt from a perch and visually sight their prey before pursuing and capturing it. They can often be spotted perching on a good vantage point- bobbing their tails and sometimes expressively lifting their small black crests. They are hungry birds too. One study from California in 1985 found that black phoebes caught an average of 1.21 prey items per minute over the course of a day. If that rate is consistent, one black phoebe can eat 73 prey items per hour; over a ten-hour hunting period that is 726 prey items per day; and over a year that adds up to 264,990 prey items (!). Black phoebe's primarily consume small wasps, spiders, flies, moths, butterflies and grasshoppers. They have even been known to fish small minnows from shallow water. Say's and eastern phoebes have similar diets.
Black- and eastern- phoebes traditionally build their nests from mud on sheer-sided cliffs near sources of water. Say's phoebes rely less on mud as a substrate- possibly because of their wider range and lesser association with waterways. All 3 species like to have a roof over their heads while nesting. The eaves of houses and spaces under porches and in garages have become new favorite nesting sites for the birds in towns within their range- and have even been attributed to widening the area in which phoebes breed. YouTube is full of home-shot vidoes of phoebes feeding their young- and even a few that have learned to take food from their host (human) family.
Eastern phoebe nests can sometimes harbor unwelcome guests. Brown-headed cowbirds, a bird that specializes in laying its eggs in the nests of other birds (a phenomenon known as 'brood-parasitism'), often call eastern phoebe nests their home. Cowbirds lay their eggs in amongst phoebe eggs, and pass along all their maternal duties to the unsuspecting phoebe parents. Cowbird chicks grow faster than their natural nest-mates by out-begging the phoebe chicks. This can result in very low nesting success rates in phoebes. In some well-studied eastern phoebe populations, only about 10% of parasitized nests fledge both phoebe and cowbird chicks- and in some areas up to 20% of nests can be parasitized. Habitat fragmentation has been linked with the spread of cowbirds around the country, and this has in turn been linked with increased parasitism in phoebe and other host bird nests.
Mark Hauber, a Professor in the Department of Psychology at Hunter University, studies the mechanisms of brood parasitism in birds around the world: including the co-evolutionary arms-race between eastern phoebes and brown-headed cowbirds. While many brood parasites actively try to kill or remove the natural eggs of their host parents from the nest, it may not be the best idea for cowbirds in phoebe nests. Dr. Hauber's work with colleagues has shown that cowbird chicks actually have the best growth rates when they allow phoebe chicks to remain with them in the nest. This is because the parent phoebes deliver more food to accommodate for their larger brood: food which the more aggressive cowbird can snag first.
[Side Note: As part of my PhD research, I found that New Zealand falcons brought more food to larger broods, but the chicks that had siblings got less food overall than single falcon chicks.]
[Side Note: As part of my PhD research, I found that New Zealand falcons brought more food to larger broods, but the chicks that had siblings got less food overall than single falcon chicks.]
Farm Rating: Friends year-round.
If you want to encourage more phoebe's around your property (and everyone should!), keeping waterways flowing and surrounded by natural vegetation is key. Count yourself lucky if you spot a cup-nest made from mud and mosses in the corner of your garage or under an eave at your house- a phoebe nest will give you hours of entertainment as you watch the parents tend to their 2 broods each summer (but be sure to keep your distance), and just think of the pest control services that one pair of Phoebes will give you over the course of a year!
If you want to encourage more phoebe's around your property (and everyone should!), keeping waterways flowing and surrounded by natural vegetation is key. Count yourself lucky if you spot a cup-nest made from mud and mosses in the corner of your garage or under an eave at your house- a phoebe nest will give you hours of entertainment as you watch the parents tend to their 2 broods each summer (but be sure to keep your distance), and just think of the pest control services that one pair of Phoebes will give you over the course of a year!
More Reading:
Wolf, Blair O. 1997. Black Phoebe (Sayornis nigricans), 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/268
All About Birds for Black Phoebe, Say's Phoebe, and Eastern Phoebe
The website of the Hauber Lab
Croston, R. & Hauber, M. E. (2012) The Ecology of Avian Brood Parasitism. Nature Education Knowledge 3(10):56
Wolf, Blair O. 1997. Black Phoebe (Sayornis nigricans), 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/268
All About Birds for Black Phoebe, Say's Phoebe, and Eastern Phoebe
The website of the Hauber Lab
Croston, R. & Hauber, M. E. (2012) The Ecology of Avian Brood Parasitism. Nature Education Knowledge 3(10):56