Post by Eaglehawk on Jan 20, 2020 3:33:25 GMT
Swamp Sparrow - Melospiza georgiana
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Passeriformes
Family: Passerellidae
Genus: Melospiza
Species: Melospiza georgiana (Latham, 1790)
The swamp sparrow (Melospiza georgiana) is a medium-sized sparrow related to the song sparrow.
Description
Adults have streaked rusty, buff and black upperparts with an unstreaked gray breast, light belly and a white throat. The wings are strikingly rusty. Most males and a few females have a rust-colored caps. Their face is gray with a dark line through the eye. They have a short bill and fairly long legs. Immature birds and winter adults usually have two brown crown stripes and much of the gray is replaced with buff.
Distribution
Swamp sparrows breed across the northern United States and boreal Canada. The southern edge of their breeding range coincides largely with the Line of Maximum Glaciation. A small number of morphologically distinct birds inhabit tidal marshes from northern Virginia to the Hudson River Estuary. This subspecies (M. g. nigrescens) winters in coastal marshes of the Carolinas and differs from the two inland swamp sparrow subspecies in having more black in a grayer overall plumage, larger bill, different songs, and a smaller average clutch size.
Geographical distribution of Swamp sparrow. Breeding Migration Year-round Nonbreeding
Breeding
Their breeding habitat is marshes, including brackish marshes, across eastern North America and central Canada. The bulky nest is attached to marsh vegetation, often just above the ground or surface of the water with leaves or grass arching over the top. The female builds a new nest each year and lays an average of four eggs per clutch. Females give a series of chips as they leave the nest, probably to ward off attacks by their mate or neighboring males.
While swamp sparrows can be found year-round in small numbers on the southern edge of their breeding range, individuals are probably all migratory, primarily migrating to the southeastern United States.
Diet
Swamp sparrows generally forage on the ground near the water's edge, in shallow water or in marsh vegetation. In winter, their diet is principally fruit and seeds, while during the breeding season their diet is mainly arthropods.
The song of the swamp sparrow is a slow monotone trill, slower than that of the chipping sparrow. A male can have a repertoire of several different trills. The common call note is a loud chip reminiscent of a phoebe.
This bird's numbers have declined due to habitat loss in some parts of its range.
Male sparrows are less intimidated by the songs of aging rivals
by Robin A. Smith, Duke University
As they get up in years, male swamp sparrow songs don't strike fear like they used to. Credit: Robert Lachlan, Queen Mary University of London
Few singers reach their sunset years with the same voice they had in younger days. Singing sparrows are no different. Duke University-led research reveals that elderly swamp sparrows don't sound quite like they used to—nor do they strike the same fear in other males who may be listening in.
Humans are remarkably good at guessing a person's age just by hearing their voice. But this is the first time the phenomenon has been demonstrated in wild animals, said Duke biology professor and study co-author Steve Nowicki.
The findings were published on January 7 in the journal Behavioral Ecology.
During the early spring, a male swamp sparrow stakes out a breeding territory and threatens any male who dares to trespass on his turf. If a potential rival enters another male's territory and starts to sing, the resident male says "Get out!" by singing back with a rapid weet-weet-weet and flying toward the intruder. Eventually, if all else fails, he attacks.
Previous research by this team showed that male swamp sparrows reach their peak as vocalists at age two, and start to decline after that, singing less frequently and less consistently as they get older.
To find out if other males take note of such changes, the team set up a speaker in the territories of 35 male swamp sparrows in a Pennsylvania marsh and played them 5-minute audio clips of stranger males recorded at age two and again at age 10.
The team measured the birds' responses, noting how closely each male approached the speaker. They found that males approached seven feet closer when they heard a potential rival's song recorded at age two than at age 10. This suggests that males are more aggressive towards younger-sounding rivals.
Males in their prime pose an obvious threat: if a resident male isn't assertive, there's a good chance that the other guy could steal his mates, said first author Matthew Zipple, a doctoral student at Duke. But apparently the song of a 10-year-old—a centenarian in bird years—doesn't warrant getting as worked up over.
If decreases in song quality in later life reflect the inevitable consequences of physical decline, the researchers believe that such changes could indicate to other males that a once-formidable male is no longer a match.
Whether song changes after mid-life make males more or less attractive to females is still unknown. "One interesting question would be, is the equation a little different from the female's point of view?" Nowicki said.
Males accumulate genetic mutations in their sperm as they age that could make them less desirable mates. On the flip side, Nowicki said, "The mere fact that he's lived this long means he must be doing something right."
phys.org/news/2020-01-male-sparrows-intimidated-songs-aging.html
Journal Reference:
Matthew N Zipple et al, Sounds of senescence: male swamp sparrows respond less aggressively to the songs of older individuals, Behavioral Ecology (2019). DOI: 10.1093/beheco/arz218
Abstract
Age-related changes in assessment signals occur in a diverse array of animals, including humans. Age-related decline in vocal quality in humans is known to affect perceived attractiveness by potential mates and voters, but whether such changes have functional implications for nonhuman animals is poorly understood. Most studies of age-related change in animal signals focus on increases in signal quality that occur soon after the age of first breeding (“delayed maturation”), but a few have shown that signal quality declines in older individuals after a mid-life peak (“behavioral senescence”). Whether other individuals are able to detect this senescent decline of assessment signals has not previously been tested. Here we use playback experiments to show that wild male swamp sparrows (Melospiza georgiana) respond more aggressively to songs from 2-year-old males as compared with songs from the same males when they are 10 years old. Senescence in signals that, like birdsong, affect reproductive success through intrasexual competition or mate choice may be of evolutionary significance.
academic.oup.com/beheco/advance-article-abstract/doi/10.1093/beheco/arz218/5697305?redirectedFrom=fulltext
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Passeriformes
Family: Passerellidae
Genus: Melospiza
Species: Melospiza georgiana (Latham, 1790)
The swamp sparrow (Melospiza georgiana) is a medium-sized sparrow related to the song sparrow.
Description
Adults have streaked rusty, buff and black upperparts with an unstreaked gray breast, light belly and a white throat. The wings are strikingly rusty. Most males and a few females have a rust-colored caps. Their face is gray with a dark line through the eye. They have a short bill and fairly long legs. Immature birds and winter adults usually have two brown crown stripes and much of the gray is replaced with buff.
Distribution
Swamp sparrows breed across the northern United States and boreal Canada. The southern edge of their breeding range coincides largely with the Line of Maximum Glaciation. A small number of morphologically distinct birds inhabit tidal marshes from northern Virginia to the Hudson River Estuary. This subspecies (M. g. nigrescens) winters in coastal marshes of the Carolinas and differs from the two inland swamp sparrow subspecies in having more black in a grayer overall plumage, larger bill, different songs, and a smaller average clutch size.
Geographical distribution of Swamp sparrow. Breeding Migration Year-round Nonbreeding
Breeding
Their breeding habitat is marshes, including brackish marshes, across eastern North America and central Canada. The bulky nest is attached to marsh vegetation, often just above the ground or surface of the water with leaves or grass arching over the top. The female builds a new nest each year and lays an average of four eggs per clutch. Females give a series of chips as they leave the nest, probably to ward off attacks by their mate or neighboring males.
While swamp sparrows can be found year-round in small numbers on the southern edge of their breeding range, individuals are probably all migratory, primarily migrating to the southeastern United States.
Diet
Swamp sparrows generally forage on the ground near the water's edge, in shallow water or in marsh vegetation. In winter, their diet is principally fruit and seeds, while during the breeding season their diet is mainly arthropods.
The song of the swamp sparrow is a slow monotone trill, slower than that of the chipping sparrow. A male can have a repertoire of several different trills. The common call note is a loud chip reminiscent of a phoebe.
This bird's numbers have declined due to habitat loss in some parts of its range.
Male sparrows are less intimidated by the songs of aging rivals
by Robin A. Smith, Duke University
As they get up in years, male swamp sparrow songs don't strike fear like they used to. Credit: Robert Lachlan, Queen Mary University of London
Few singers reach their sunset years with the same voice they had in younger days. Singing sparrows are no different. Duke University-led research reveals that elderly swamp sparrows don't sound quite like they used to—nor do they strike the same fear in other males who may be listening in.
Humans are remarkably good at guessing a person's age just by hearing their voice. But this is the first time the phenomenon has been demonstrated in wild animals, said Duke biology professor and study co-author Steve Nowicki.
The findings were published on January 7 in the journal Behavioral Ecology.
During the early spring, a male swamp sparrow stakes out a breeding territory and threatens any male who dares to trespass on his turf. If a potential rival enters another male's territory and starts to sing, the resident male says "Get out!" by singing back with a rapid weet-weet-weet and flying toward the intruder. Eventually, if all else fails, he attacks.
Previous research by this team showed that male swamp sparrows reach their peak as vocalists at age two, and start to decline after that, singing less frequently and less consistently as they get older.
To find out if other males take note of such changes, the team set up a speaker in the territories of 35 male swamp sparrows in a Pennsylvania marsh and played them 5-minute audio clips of stranger males recorded at age two and again at age 10.
The team measured the birds' responses, noting how closely each male approached the speaker. They found that males approached seven feet closer when they heard a potential rival's song recorded at age two than at age 10. This suggests that males are more aggressive towards younger-sounding rivals.
Males in their prime pose an obvious threat: if a resident male isn't assertive, there's a good chance that the other guy could steal his mates, said first author Matthew Zipple, a doctoral student at Duke. But apparently the song of a 10-year-old—a centenarian in bird years—doesn't warrant getting as worked up over.
If decreases in song quality in later life reflect the inevitable consequences of physical decline, the researchers believe that such changes could indicate to other males that a once-formidable male is no longer a match.
Whether song changes after mid-life make males more or less attractive to females is still unknown. "One interesting question would be, is the equation a little different from the female's point of view?" Nowicki said.
Males accumulate genetic mutations in their sperm as they age that could make them less desirable mates. On the flip side, Nowicki said, "The mere fact that he's lived this long means he must be doing something right."
phys.org/news/2020-01-male-sparrows-intimidated-songs-aging.html
Journal Reference:
Matthew N Zipple et al, Sounds of senescence: male swamp sparrows respond less aggressively to the songs of older individuals, Behavioral Ecology (2019). DOI: 10.1093/beheco/arz218
Abstract
Age-related changes in assessment signals occur in a diverse array of animals, including humans. Age-related decline in vocal quality in humans is known to affect perceived attractiveness by potential mates and voters, but whether such changes have functional implications for nonhuman animals is poorly understood. Most studies of age-related change in animal signals focus on increases in signal quality that occur soon after the age of first breeding (“delayed maturation”), but a few have shown that signal quality declines in older individuals after a mid-life peak (“behavioral senescence”). Whether other individuals are able to detect this senescent decline of assessment signals has not previously been tested. Here we use playback experiments to show that wild male swamp sparrows (Melospiza georgiana) respond more aggressively to songs from 2-year-old males as compared with songs from the same males when they are 10 years old. Senescence in signals that, like birdsong, affect reproductive success through intrasexual competition or mate choice may be of evolutionary significance.
academic.oup.com/beheco/advance-article-abstract/doi/10.1093/beheco/arz218/5697305?redirectedFrom=fulltext