Re: "Juvenile cowbirds sneak out at night" - RE: [cayugabirds-l] Cowbirds
Thanks, Anne, for clearing that up. It’s much less bizarre that the fledglings, after being old enough fly well, move out of the host territory at dusk to roost, but still fascinating because it’s not clear why they should leave if they are only going back again in the morning. Maybe they don’t know the boundaries, or maybe it’s a bit of exploration, seeking out places where they might feed on their own later on. When they return by day to the host territory, do they continue to be fed by the hosts? - - Dave Nutter > On Apr 12, 2020, at 10:14 AM, AB Clark wrote: > the FLEDGLINGS (juveniles that have left the nest and are flying, at about > 10-20 days old) are often leaving on their own, at dusk, to ROOST (sit in the > dark) away from their foster-parents territories, but still returning to > those territories in daytime. > -- Cayugabirds-L List Info: http://www.NortheastBirding.com/CayugabirdsWELCOME http://www.NortheastBirding.com/CayugabirdsRULES http://www.NortheastBirding.com/CayugabirdsSubscribeConfigurationLeave.htm ARCHIVES: 1) http://www.mail-archive.com/cayugabirds-l@cornell.edu/maillist.html 2) http://www.surfbirds.com/birdingmail/Group/Cayugabirds 3) http://birdingonthe.net/mailinglists/CAYU.html Please submit your observations to eBird: http://ebird.org/content/ebird/ --
Re: "Juvenile cowbirds sneak out at night" - RE: [cayugabirds-l] Cowbirds
“Young Cowbirds won’t you come out tonight? Come out tonight? Come out tonight And dance by the light of the moon.” Those who dwell among the beauties and mysteries of the earth are never alone or weary of life. Rachel Carson. > On Apr 12, 2020, at 4:47 PM, Magnus Fiskesjo > wrote: > > > Thanks! Yes Indeed it seems that in the 2015 study, cowbird youngsters > (*fledglings*) were *spending the night away* from their slave parents and > then return *not* to the *nest* but to the foster parents' location -- for > more slave feeding. This scenario does make more sense, yes, so it may well > be I misremembered about the *nest* part. The *fledglings* going out on their > own would also resolve, perhaps, John Confer's points of doubt about body > temperature. > > But note, that we are not up to date, yet -- the 2015 publication was > apparently superseded by new research which expanded, to discover the > "teenager party" as reported in Living Bird, I believe some time in 2017-2019 > -- that is, about young cowbirds *not* sitting in the dark (which makes > little or no sense, to me, at least! why would they do that?), but hanging > out with young cowbird peers which would enable them to build cowbirdness. To > me it looks like this additional discovery was not yet made in 2015 -- so in > that study they mistakenly concluded that the young cowbird was sitting alone > in the dark, instead of going to his peer party. > > If I do find it again, I'll forward it. > > --If anyone on this list has a digital copy already, please post a copy. > > Many thanks again, over and out for now, > Magnus > -- > Magnus Fiskesjö, PhD > Associate Professor, Department of Anthropology, Cornell University > McGraw Hall, Room 201. Ithaca, NY 14853, USA > E-mail: magnus.fiske...@cornell.edu, or: n...@cornell.edu > > From: AB Clark [anneb.cl...@gmail.com] > Sent: Sunday, April 12, 2020 10:14 AM > To: Magnus Fiskesjo > Cc: John Confer; CAYUGABIRDS-L > Subject: Re: "Juvenile cowbirds sneak out at night" - RE: [cayugabirds-l] > Cowbirds > > At the risk of making this a longer-than-wanted discussion, I will briefly > answer—and then retreat! > > I just read Magnus’ report on Louder et al’s study from U Illinois and > downloaded the actual paper and here is the story. No one is leaving at 3 > am! Or flying out of a nest as a nestling. Too much fine grained > terminology is leading to misunderstandings, but it is a fascinating paper. > > SO—the question that the researchers were interested in was whether actual > biological mothers of young cowbirds were somehow leading their own > fledglings away from the Host-parents territory. The answer is NO. But the > FLEDGLINGS (juveniles that have left the nest and are flying, at about 10-20 > days old) are often leaving on their own, at dusk, to ROOST (sit in the dark) > away from their foster-parents territories, but still returning to those > territories in daytime. > > The confusions come in because they put the little radios on the cowbird > young on about the last day when they were still in their host-nests as > NESTLINGS, but the observations they report were all on FLEDGLINGS, young > that had left their nests, never to return. In Icterids, nestlings do not > leave flighted, but they can flutter and can cling and climb with strong well > developed legs. From what I remember, young cowbirds develop a little faster > than some. So maybe they fly as early as 5-6 days after fledging—I have to > check. > > But it is during the later FLEDGLING stage, out of the nests and mobile, that > they start to disappear off foster-territory in the evening. Sunset isn’t > dark, so they can still move easily; apparently motivated by whatever gets a > cowbird to become a cowbird, they often left to roost alone, during the next > 3 weeks of still being associated with foster-parents during the day. And > their non-doting cowbird mothers don’t have anything to do with it, because > they were also being tracked by radios and triangulating receiver towers, and > mom-cowbirds were not present during these movements. > > Did it bring juvenile cowbirds into contact with other cowbirds? Apparently > not, at that stage. But the “go away, young man/cowbird” urge was already > present. > > > So thanks, Magnus, for bringing our attention to this really interesting > report! (I can send it to anyone who wants to read it!) > > Anne > > Anne B Clark > 147 Hile School Rd > Freeville, NY 13068 > 607-222-0905 > anneb.cl...@gmail.com<mailto:anneb.cl...@gmail.com> > > > > On Apr 11,
RE: "Juvenile cowbirds sneak out at night" - RE: [cayugabirds-l] Cowbirds
Thanks! Yes Indeed it seems that in the 2015 study, cowbird youngsters (*fledglings*) were *spending the night away* from their slave parents and then return *not* to the *nest* but to the foster parents' location -- for more slave feeding. This scenario does make more sense, yes, so it may well be I misremembered about the *nest* part. The *fledglings* going out on their own would also resolve, perhaps, John Confer's points of doubt about body temperature. But note, that we are not up to date, yet -- the 2015 publication was apparently superseded by new research which expanded, to discover the "teenager party" as reported in Living Bird, I believe some time in 2017-2019 -- that is, about young cowbirds *not* sitting in the dark (which makes little or no sense, to me, at least! why would they do that?), but hanging out with young cowbird peers which would enable them to build cowbirdness. To me it looks like this additional discovery was not yet made in 2015 -- so in that study they mistakenly concluded that the young cowbird was sitting alone in the dark, instead of going to his peer party. If I do find it again, I'll forward it. --If anyone on this list has a digital copy already, please post a copy. Many thanks again, over and out for now, Magnus -- Magnus Fiskesjö, PhD Associate Professor, Department of Anthropology, Cornell University McGraw Hall, Room 201. Ithaca, NY 14853, USA E-mail: magnus.fiske...@cornell.edu, or: n...@cornell.edu From: AB Clark [anneb.cl...@gmail.com] Sent: Sunday, April 12, 2020 10:14 AM To: Magnus Fiskesjo Cc: John Confer; CAYUGABIRDS-L Subject: Re: "Juvenile cowbirds sneak out at night" - RE: [cayugabirds-l] Cowbirds At the risk of making this a longer-than-wanted discussion, I will briefly answer—and then retreat! I just read Magnus’ report on Louder et al’s study from U Illinois and downloaded the actual paper and here is the story. No one is leaving at 3 am! Or flying out of a nest as a nestling. Too much fine grained terminology is leading to misunderstandings, but it is a fascinating paper. SO—the question that the researchers were interested in was whether actual biological mothers of young cowbirds were somehow leading their own fledglings away from the Host-parents territory. The answer is NO. But the FLEDGLINGS (juveniles that have left the nest and are flying, at about 10-20 days old) are often leaving on their own, at dusk, to ROOST (sit in the dark) away from their foster-parents territories, but still returning to those territories in daytime. The confusions come in because they put the little radios on the cowbird young on about the last day when they were still in their host-nests as NESTLINGS, but the observations they report were all on FLEDGLINGS, young that had left their nests, never to return. In Icterids, nestlings do not leave flighted, but they can flutter and can cling and climb with strong well developed legs. From what I remember, young cowbirds develop a little faster than some. So maybe they fly as early as 5-6 days after fledging—I have to check. But it is during the later FLEDGLING stage, out of the nests and mobile, that they start to disappear off foster-territory in the evening. Sunset isn’t dark, so they can still move easily; apparently motivated by whatever gets a cowbird to become a cowbird, they often left to roost alone, during the next 3 weeks of still being associated with foster-parents during the day. And their non-doting cowbird mothers don’t have anything to do with it, because they were also being tracked by radios and triangulating receiver towers, and mom-cowbirds were not present during these movements. Did it bring juvenile cowbirds into contact with other cowbirds? Apparently not, at that stage. But the “go away, young man/cowbird” urge was already present. So thanks, Magnus, for bringing our attention to this really interesting report! (I can send it to anyone who wants to read it!) Anne Anne B Clark 147 Hile School Rd Freeville, NY 13068 607-222-0905 anneb.cl...@gmail.com<mailto:anneb.cl...@gmail.com> On Apr 11, 2020, at 10:02 PM, Magnus Fiskesjo mailto:magnus.fiske...@cornell.edu>> wrote: Thanks. Yes it's curious and hard-to-believe and I think that's why I remember so clearly reading about this in the Lab of O's Living Bird member's magazine, but as I said, can't find that article online--perhaps it is only in their printed version which I must have read 2017 or later. AllAboutBird account is much earlier, 2009, and does not bring up what must be some NEW research ( https://www.allaboutbirds.org/news/if-brown-headed-cowbirds-are-reared-by-other-species-how-do-they-know-they-are-cowbirds-when-they-grow-up/ ). Regardless, just now a friend sent me this 2015 report below, which mentions the SAME strange observations that I believe I read in Living Bird -- with
Re: "Juvenile cowbirds sneak out at night" - RE: [cayugabirds-l] Cowbirds
At the risk of making this a longer-than-wanted discussion, I will briefly answer—and then retreat! I just read Magnus’ report on Louder et al’s study from U Illinois and downloaded the actual paper and here is the story. No one is leaving at 3 am! Or flying out of a nest as a nestling. Too much fine grained terminology is leading to misunderstandings, but it is a fascinating paper. SO—the question that the researchers were interested in was whether actual biological mothers of young cowbirds were somehow leading their own fledglings away from the Host-parents territory. The answer is NO. But the FLEDGLINGS (juveniles that have left the nest and are flying, at about 10-20 days old) are often leaving on their own, at dusk, to ROOST (sit in the dark) away from their foster-parents territories, but still returning to those territories in daytime. The confusions come in because they put the little radios on the cowbird young on about the last day when they were still in their host-nests as NESTLINGS, but the observations they report were all on FLEDGLINGS, young that had left their nests, never to return. In Icterids, nestlings do not leave flighted, but they can flutter and can cling and climb with strong well developed legs. From what I remember, young cowbirds develop a little faster than some. So maybe they fly as early as 5-6 days after fledging—I have to check. But it is during the later FLEDGLING stage, out of the nests and mobile, that they start to disappear off foster-territory in the evening. Sunset isn’t dark, so they can still move easily; apparently motivated by whatever gets a cowbird to become a cowbird, they often left to roost alone, during the next 3 weeks of still being associated with foster-parents during the day. And their non-doting cowbird mothers don’t have anything to do with it, because they were also being tracked by radios and triangulating receiver towers, and mom-cowbirds were not present during these movements. Did it bring juvenile cowbirds into contact with other cowbirds? Apparently not, at that stage. But the “go away, young man/cowbird” urge was already present. So thanks, Magnus, for bringing our attention to this really interesting report! (I can send it to anyone who wants to read it!) Anne Anne B Clark 147 Hile School Rd Freeville, NY 13068 607-222-0905 anneb.cl...@gmail.com > On Apr 11, 2020, at 10:02 PM, Magnus Fiskesjo > wrote: > > > Thanks. Yes it's curious and hard-to-believe and I think that's why I > remember so clearly reading about this in the Lab of O's Living Bird member's > magazine, but as I said, can't find that article online--perhaps it is only > in their printed version which I must have read 2017 or later. AllAboutBird > account is much earlier, 2009, and does not bring up what must be some NEW > research ( > https://www.allaboutbirds.org/news/if-brown-headed-cowbirds-are-reared-by-other-species-how-do-they-know-they-are-cowbirds-when-they-grow-up/ > ). > > Regardless, just now a friend sent me this 2015 report below, which mentions > the SAME strange observations that I believe I read in Living Bird -- with > minor differences: this report mentions chicks as nightly departing foster > nests after sunset, not 3am, BUT returning only at dawn; also, it says the > nightly escape is solitary, NOT to congregate with other young cowbirds in a > 'teenager party' as I remember from Living Bird (which also said that the > field congregation was only revealed to Science after new tracking that was > launched only once researchers had found that the cowbird chick they > monitored was missing from its nest at night! So, maybe the 'teenager party' > was only found out after simultaneously tracking several youngsters?) > > Anyhow, here goes: > > https://www.sciencedaily.com/releases/2015/11/151102152607.htm > > Science News > > Juvenile cowbirds sneak out at night > Date:November 2, 2015 > Source:University of Illinois at Urbana-Champaign > > A new study explores how a young cowbird, left as an egg in the nest of a > different species, grows up to know it's a cowbird and not a warbler, thrush > or sparrow. > > The study, published in Animal Behaviour, reveals that cowbird juveniles > leave the host parents at dusk and spend their nights in nearby fields, > returning just after daybreak. This behavior likely plays a role in the > cowbirds' ability to avoid imprinting on their host parents. > > "If I took a chickadee and I put it in a titmouse nest, the chickadee would > start learning the song of the titmouse and it would actually learn the > titmouse behaviors," said Matthew Louder, who conducted the study as a Ph.D. > student with Illinois Natural History Survey avian ecologist Jeff Hoover and > INHS biological surveys coordinator Wendy Schelsky. "And then, when it was > old enough, the chickadee would prefer to mate with the titmouse, which would > be an
"Juvenile cowbirds sneak out at night" - RE: [cayugabirds-l] Cowbirds
Thanks. Yes it's curious and hard-to-believe and I think that's why I remember so clearly reading about this in the Lab of O's Living Bird member's magazine, but as I said, can't find that article online--perhaps it is only in their printed version which I must have read 2017 or later. AllAboutBird account is much earlier, 2009, and does not bring up what must be some NEW research ( https://www.allaboutbirds.org/news/if-brown-headed-cowbirds-are-reared-by-other-species-how-do-they-know-they-are-cowbirds-when-they-grow-up/ ). Regardless, just now a friend sent me this 2015 report below, which mentions the SAME strange observations that I believe I read in Living Bird -- with minor differences: this report mentions chicks as nightly departing foster nests after sunset, not 3am, BUT returning only at dawn; also, it says the nightly escape is solitary, NOT to congregate with other young cowbirds in a 'teenager party' as I remember from Living Bird (which also said that the field congregation was only revealed to Science after new tracking that was launched only once researchers had found that the cowbird chick they monitored was missing from its nest at night! So, maybe the 'teenager party' was only found out after simultaneously tracking several youngsters?) Anyhow, here goes: https://www.sciencedaily.com/releases/2015/11/151102152607.htm Science News Juvenile cowbirds sneak out at night Date:November 2, 2015 Source:University of Illinois at Urbana-Champaign A new study explores how a young cowbird, left as an egg in the nest of a different species, grows up to know it's a cowbird and not a warbler, thrush or sparrow. The study, published in Animal Behaviour, reveals that cowbird juveniles leave the host parents at dusk and spend their nights in nearby fields, returning just after daybreak. This behavior likely plays a role in the cowbirds' ability to avoid imprinting on their host parents. "If I took a chickadee and I put it in a titmouse nest, the chickadee would start learning the song of the titmouse and it would actually learn the titmouse behaviors," said Matthew Louder, who conducted the study as a Ph.D. student with Illinois Natural History Survey avian ecologist Jeff Hoover and INHS biological surveys coordinator Wendy Schelsky. "And then, when it was old enough, the chickadee would prefer to mate with the titmouse, which would be an evolutionary dead end," he said. Louder is now a postdoctoral researcher with East Carolina University in North Carolina and Hunter College in New York. The imprinting process is widespread among birds and other animals, but brood parasites like the cowbird appear to be resistant to imprinting. They will imprint on a different species if confined with that species for an extended period of time in a cage, but the birds don't appear to do so in the wild. Cowbird hosts, such as the prothonotary warblers in this study, have their own habits and habitats, and seldom choose to live where the cowbirds live or eat what they eat. Prothonotary warblers, for example, live in forests and dine on insects and caterpillars. Cowbirds spend most of their adult lives in open fields and prairies, and while they do eat insects, about three-quarters of their diet consists of seeds. "Among other things, cowbirds have got to learn to eat like cowbirds or they're not going to survive very long," Hoover said. The researchers wanted to test the hypothesis that cowbird moms are the ones that lead their offspring out of the forest. There was some support for this idea. A recent study from the same team found that cowbird females don't simply abandon their eggs in another species' nest. They pay attention to whether the young birds survive, sometimes wrecking the nests of birds that kick the cowbird eggs out of their nests. The cowbird females also return to nests where young cowbirds survived to fledging age. Cowbird females are often spotted in the vicinity of cowbird nestlings, Schelsky said, and sometimes respond (with vocalizations, not food) to the nestlings' begging calls. To track the birds in the forest and prairie, the researchers put radio telemetry transmitters on the cowbird nestlings and on adult female cowbirds in the forest where the host parents made their nests. The team took blood from the birds and conducted genetic analyses to match the juveniles (and their radio signals) to their biological mothers. But tracking the birds, even with the radio transmitters, was next to impossible, Louder said. He tried for a year, but was unable to get meaningful data. Then study co-author Michael Ward, a professor of natural resources and environmental sciences at the University of Illinois, came up with a new approach. "He helped construct an automated telemetry system," Louder said. "We put up three radio towers, each with six antennas on it, so you have 360-degree directional coverage. All three towers track
