Hey everybody!
If you're looking for the IL Migration Report, it has been migrated to a separate blog which you can access and bookmark here: http://ilmigration.blogspot.com
Now, the focus of this blog will return to general ornithology.
Happy birding!
Sunday, 5 May 2013
Sunday, 14 April 2013
Preparing for Migration
Hey Everybody!
Though interest in bird migration in general has always been part of birding, interest in forecasting migration and understanding the weather that affects it seems to be growing these days, especially as technology becomes more pervasive. So, to feed your curiosity, the IL Ornithological Society and IL Young Birders have decided to begin our own regional BirdCast-type project. Daily, I will be delivering a report both of what migration has played out in the past 24 hours, and what to expect in the next 24 hours. I will send out the first of these emails later this evening as the sun sets and the first migrants start moving. First, I wanted to share with you all some resources for understanding migration live with the use of Radar.
So without further adieu, here are some resources I use to track migration and weather. These are going to be my best friends in the coming months, and if you want to follow migration, they should be yours too:
Overall tutorials about migration, Radar Ornithology, and related topics can be found at the following sources. I encourage you to use them if you're interested:
Finally, the Cornell Lab et al. have a website called BirdCast (http://birdcast.info), which posts weekly forecasts and analysis.
That's all the introductory stuff, folks. I know it's a lot, but we only need to do this once. I guess I just like sharing too much. Keep an eye out for my first migration report. It should be relatively exciting tonight compared to the past few days.
Though interest in bird migration in general has always been part of birding, interest in forecasting migration and understanding the weather that affects it seems to be growing these days, especially as technology becomes more pervasive. So, to feed your curiosity, the IL Ornithological Society and IL Young Birders have decided to begin our own regional BirdCast-type project. Daily, I will be delivering a report both of what migration has played out in the past 24 hours, and what to expect in the next 24 hours. I will send out the first of these emails later this evening as the sun sets and the first migrants start moving. First, I wanted to share with you all some resources for understanding migration live with the use of Radar.
So without further adieu, here are some resources I use to track migration and weather. These are going to be my best friends in the coming months, and if you want to follow migration, they should be yours too:
- http://weather.rap.ucar.edu/ - Monitor radar, surface winds, and higher altitude winds. This is probably the most valuable resource, as you can track the reflectivity and velocity live as well as back in the past 6 days. It's awesome.
- http://www.aos.wisc.edu/
weather/wx_obs/Nexrad.html - Simpler radar display. Look for blue, donut-shaped forms that appear after sunset. These are birds. - http://www.intellicast.com/
National/Surface/Mixed.aspx - Just what I use for surface analysis. Look for fronts pointing north. If you look now, there's a warm front moving due north, which is driven by a nearby low-pressure system. Low pressure systems spin counterclockwise, so we will always experience southerly winds when east of a low pressure system.
Overall tutorials about migration, Radar Ornithology, and related topics can be found at the following sources. I encourage you to use them if you're interested:
- http://birdcast.info/forecast/
understanding-birds-and-radar/ - http://virtual.clemson.edu/
groups/birdrad/ - http://www.njaudubon.org/
SectionOases/ HowNEXRADseestheatmosphere. aspx
Finally, the Cornell Lab et al. have a website called BirdCast (http://birdcast.info), which posts weekly forecasts and analysis.
That's all the introductory stuff, folks. I know it's a lot, but we only need to do this once. I guess I just like sharing too much. Keep an eye out for my first migration report. It should be relatively exciting tonight compared to the past few days.
Saturday, 6 April 2013
Give 'em a Day and the World Will Know
A Spotted Redshank, an ABA Code 4, appeared in Goose Pond Fish and Wildlife Area in southern Indiana recently, and conveniently ended many of our wintertime birding blues. Tens of birders have gone to the chase, with people from at least 5 states appearing almost as suddenly as the bird itself to add it to their life lists, their overall experience with birds, and maybe even just for the thrill of the chase. The bird is stunningly rare, and its appearance in the center of the continent is mind-blowing to say the least, but something else mirrors my amazement with the bird: its first appearance was two days ago, and yet birders from around the entire east are already gravitating towards this bird. This bird, while providing too an example of the wonders of wandering shorebirds, provides an example of the effect the information revolution has had on even the outdoorsy and nature-oriented pursuit that is birding.
The curtain opens at 9:30 AM on Thursday, March 28th. The Indiana Birding listserv is enjoying the perks of the long-delayed springtime arrivals, and suddenly, a short and concise email about a Spotted Redshank at Goose Pond pops up nonchalantly, making followers of Indiana birding aware of Indiana's first mega-rarity of 2013. In less than an hour, a series of forwards, re-tweets and shares bring the news across the east and probably further, and the web of information continues to grow. More people know about it with each hour, and by the end of the day, people are planning the chase for the next day or even that night. It's still Thursday the sun has barely set, and a northern Illinois birder, for example, is preparing to drive halfway there that night, fruitlessly attempt to sleep in a motel, and drive down to it early Friday morning. I know that many of us can get lost in our various forms of technology and start to believe that this is normal, that this is expected, but taking a step back and looking at the greater scheme of things, this is truly miraculous.
What makes this even more mind-blowing is that we're talking about an activity that focuses exclusively on nature in the outdoors. With an activity like birding, one wouldn't immediately associate the use of today's technology to such sophistication with the pursuit, but with further investigation, one would realize that birding is made of an extremely, almost unbelievably, connected bunch of people. Birding, through the years, has developed a system of codes, etiquette, and language to be used with modern technology. Birders use a myriad of blogs, email listservs, Twitter, almost every function of Facebook, and leave traces almost everywhere they go on the internet. Through these media, birders' sightings and ideas make up one of the most publicly accessible, scientifically relevant, and under-appreciated conglomerates of information in existence, and yet it goes on unnoticed right under the noses of the media and the majority of the public. Amazing!
It's this connectedness that made all the additions to the life lists and experience of a variety of birders possible, and that's pretty darn cool. It's one of the shining examples of the benefits of social media, and it does and doesn't surprise me that it doesn't attain more notice. Regardless, for those of you who can remember a time when the birding community was connected by a loose network of people who had each other's phone numbers, you can really appreciate the change social media has made. In this way, though social media is often blamed for disconnecting people from nature and the outside world (not without merit), it has also been instrumental in connecting people all over the country to nature, be it for the first time, or as an enhancement to one's previous experience. This is something I really appreciate, and I hope you all do too.
Just a few thoughts from out my way. Happy birding!
The curtain opens at 9:30 AM on Thursday, March 28th. The Indiana Birding listserv is enjoying the perks of the long-delayed springtime arrivals, and suddenly, a short and concise email about a Spotted Redshank at Goose Pond pops up nonchalantly, making followers of Indiana birding aware of Indiana's first mega-rarity of 2013. In less than an hour, a series of forwards, re-tweets and shares bring the news across the east and probably further, and the web of information continues to grow. More people know about it with each hour, and by the end of the day, people are planning the chase for the next day or even that night. It's still Thursday the sun has barely set, and a northern Illinois birder, for example, is preparing to drive halfway there that night, fruitlessly attempt to sleep in a motel, and drive down to it early Friday morning. I know that many of us can get lost in our various forms of technology and start to believe that this is normal, that this is expected, but taking a step back and looking at the greater scheme of things, this is truly miraculous.
 |
| A shot of the Spotted Redshank by Ryan Sanderson http://www.flickr.com/photos/ryanjsanderson/8603462831/ |
What makes this even more mind-blowing is that we're talking about an activity that focuses exclusively on nature in the outdoors. With an activity like birding, one wouldn't immediately associate the use of today's technology to such sophistication with the pursuit, but with further investigation, one would realize that birding is made of an extremely, almost unbelievably, connected bunch of people. Birding, through the years, has developed a system of codes, etiquette, and language to be used with modern technology. Birders use a myriad of blogs, email listservs, Twitter, almost every function of Facebook, and leave traces almost everywhere they go on the internet. Through these media, birders' sightings and ideas make up one of the most publicly accessible, scientifically relevant, and under-appreciated conglomerates of information in existence, and yet it goes on unnoticed right under the noses of the media and the majority of the public. Amazing!
 |
| A Stream of Communication |
It's this connectedness that made all the additions to the life lists and experience of a variety of birders possible, and that's pretty darn cool. It's one of the shining examples of the benefits of social media, and it does and doesn't surprise me that it doesn't attain more notice. Regardless, for those of you who can remember a time when the birding community was connected by a loose network of people who had each other's phone numbers, you can really appreciate the change social media has made. In this way, though social media is often blamed for disconnecting people from nature and the outside world (not without merit), it has also been instrumental in connecting people all over the country to nature, be it for the first time, or as an enhancement to one's previous experience. This is something I really appreciate, and I hope you all do too.
Just a few thoughts from out my way. Happy birding!
Tuesday, 5 March 2013
Where Do Birds Go During Blizzards?
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| Cold, barren, bird-less... |
Before we take pity on the birds, we must remember that millions of years of adaptation have morphed these creatures into a form wherein they are highly able to eek out a living in the winter. But what does this mean? In nature, any adaptation is always a compromise, a balance, between the new and the old, as the new develops from the old. For most songbirds, the old behavior is to cover larger areas in search of every morsel of food in every nook and cranny to reap the greatest benefits from their territory. For example, Baltimore Oriole pairs maintain a territory around the size of a football field during the breeding season. While doing this, they must defend their territory from intruders and themselves from predators. But this old way of behavior must change entirely for the winter, and especially during a snowstorm.
Our first factor in winter survival is that food is far less evenly distributed, with some areas being supplied with super-abundant food, while others have no available food at all. With food sources fewer and farther in between, songbirds have to find these isolated food sources to supply their daily energy needs. This breaks down the breeding season concept of territory. Now that resident songbirds no longer have to defend territory containing nests, they can roam more freely in search of reliable food sources. Once they find them, the bird is more likely to stay there because constantly searching for food requires much more energy in the cold, which is the second factor in adapting to survival in the winter. With more energy used to stay warm, it makes more sense to stop wandering and stay put in areas that will reliably provide food for a sustained period of time, e.g. feeders or large areas packed fruiting plants. That's where the initial adaptation is.
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| European winter feeding flock http://www.flickr.com/photos/remarkable-trees/6858760461/ |
The breeding season could be said to tear birds apart, and then the challenge of surviving winter, especially snowstorms, brings them back together. It would be accurate to summarize this process by saying that once the territorial boundaries of breeding songbirds break down, and food sources become more difficult to find, songbirds adapt their behavior to cluster together in social feeding flocks, and remain tight around food rich areas. That's all it is: an adaptation of behavior to survive in the winter.
With more birds clustered tightly in specific areas, this leaves greater areas of perfectly desirable habitat, well, bird-less because they lack reliable food sources. And voila!! The perfect recipe for making it seem like resident songbirds "disappear" in a snowstorm, and the winter overall.
Winter is a perfect time to see this strategy in survival--how staying alive requires an exact formula that results from millions of years of adaptation in similar conditions. That's not to say that songbirds are never found alone in the winter, because they are. That's not to that songbirds don't die in the winter, because they do, but the majority survive in an average winter, and there's a reason for that.
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| Stunning winter Cardinal by Daniel Behm http://www.flickr.com/photos/30604643@N03/6535533013/ |
Saturday, 5 January 2013
A Thought-trip to a Fading Paradise
Remember back to the cool and humid days of spring, when all areas were bursting with lush, green life and blazing new colors. When life was exploding at the seams and taking on all forms and sounds. Let's forget the CBC's, Gull-watching, and face-numbing lake scanning of this season for a while, and think back to the little bundles of energy that we call the neotropical migrants. This time of year, they often become an out-of-sight, out-of-mind-type situation. We simply forget about them in place of gulls, finches, ducks and owls. But never fear, they are definitely still in existence. They are far south, deliberating territories and mingling with tropical residents that many of us have never heard of.
Let us descend on a hot and humid forest, shining with green just after a short rain shower. Alien sounds are blasting out of the forest. We hear the unearthly song of the Screaming Piha, the movie sound-effect calls of the Crested Oropendola, and the buzzy call notes of the rainbow of Tanagers (e.g. Paradise Tanager to the right) within an endless series of feeding flocks and leks. The forest is adorned with a huge variety of birds. But these birds are not our focus. Not the singing, nor the dancing, nor the displaying. We must focus on the inconspicuous, tiny passerines whose only vocalizations are nonbreeding call notes. In the middle of a pleasant morning's birding in the midst of this assortment, we realize that these birds are fighting for their lives against each other and their environment; one that is rapidly changing behind their backs.
The battle begins in the late summer, thousands of miles back in the North American boreal forest, when a hormonal shift causes the birds to feed frantically on anything they can find, and fatten up. After exponential growth in body weight, the bird, we'll say a young female Black-throated Green Warbler, gets the jitters, and when the right weather presents the opportunity, she instinctively rides the winds off to south (a miracle in itself). By September, she's survived the leap-frogging across patches of green over hundreds of American miles, and the long-haul, non-stop, over the Gulf of Mexico that make up her migration, and has made it to a decent forest stand in Central America. She is finally able to begin making a living in her first nonbreeding season.
Even before humans were around, first-year female songbirds did not have forest ecology in their favor. They are at the bottom of the passerine social hierarchy; in addition to competition between species for resources like food and territory, our female must compete with aggressive adult males, cunning adult females, and other youngsters as desperate and inexperienced as herself. As a result of this hierarchy, she ends up with some of the lowest quality forest available, pushed all the way to the dry and nutrient-deficient forest edge, a landscape quite alien to her. With the addition of human life, what was once a sprawl of rainforest that provided plenty of remaining territory for her has been replaced with a sprawl of farmland and rural communities. With so much of the necessary nonbreeding habitat destroyed, our female is now subject to new challenges to which she is not adapted. She experiences a sparsity of the food that would be easily found deeper in the jungle. Now in a more open area, she comes into contact with new predators in greater numbers, and is more vulnerable to them under the scattered cover. And possibly worst of all, she comes into contact with neurotoxic pesticides. Many countries in Central and South America do not have the bans on dangerous pesticides that we do in the United States. Organochlorides and other neurotoxins used to defend crops from insect infestation have wiped out unbelievable numbers of flocking migrants such as Swainson's Hawks and Dickcissels. Our young female, five inches long at .3 ounces, barely stands a chance. Even if she isn't taken by them, pesticides often disrupt migrants' navigational senses. More vagrants for birders, but not good news for birds.
Facing malnourishment, predation, and neurotoxic pesticides, young passerines especially face an enormous problem in their wintering grounds. Many of their original high quality wintering grounds no longer exist, so more birds from the North American breeding population must make due with the smaller amount of high quality habitat; it's no wonder that more and more of the population is being pushed to the margins of their habitat. In some highly fragmented places, only the strongest adult males are getting the highest quality habitat. This puts a worrysome percentage of the breeding population in quite a precarious position. It's no wonder that it's becoming increasingly difficult to find Acadian Flycatchers, Wood Thrushes, and Cerulean Warblers!
But all is not lost...or at least not yet. The efforts of scientists are providing us with the information we need to properly conserve our beloved neotropical migrants, and the message is starkly clear: neotropical migrants absolutely need large areas of untouched, high quality forest to survive. No buts. There still are some sufficient areas, and luckily not all young passerines will experience what our hypothetical female has, but to preserve these areas, action is needed immediately. After all, once a rainforest is gone, nutrients are gone with it, and aridlands take their place, making it extremely difficult to reestablish the forest. Fully shade-grown coffee industries and the efforts of numerous conservation organizations are crucial to the cause of the neotropical migrant, but as always more is needed. The long-term, gradual decline in the population even when we have made a great effort in the States to preserve their breeding habitat has shown that Houston, we have a problem, and specifically one outside of the North American Continent. It is not a comforting message.
So the next time you see a neotropical migrant, say, a young female Black-throated Green Warbler, think of the grand cycle and natural drama it has participated in. Think of the tens of thousands of miles it has flown, and all of the challenges it has faced. Think of how lucky that individual is to be living. It is sometimes said that 40% of the North American breeding songbird population has been lost since the 50's, with some species' populations nose-diving a frightening 80%. With the obstacles many young birds face in the tropics, it really is amazing that populations keep chugging along. So all I ask is not to take them for granted. We are blessed with the avifauna of our time, and it's a travesty to think that they may not exist for future generations.
Overall, the best we can do is to keep learning. Any observations of the birds are scientifically relevant; the more we know about them, the better we can protect them. So after we've endured the painful yet rewarding time that is winter birding and spring comes around, be sure to get out there and find some warblers! But then again, I don't have to tell you to do that, do I?
 |
| Paradise Tanager by Nathan Rupert |
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| Young female Black-throated Green Warbler by Arthur Morris |
The battle begins in the late summer, thousands of miles back in the North American boreal forest, when a hormonal shift causes the birds to feed frantically on anything they can find, and fatten up. After exponential growth in body weight, the bird, we'll say a young female Black-throated Green Warbler, gets the jitters, and when the right weather presents the opportunity, she instinctively rides the winds off to south (a miracle in itself). By September, she's survived the leap-frogging across patches of green over hundreds of American miles, and the long-haul, non-stop, over the Gulf of Mexico that make up her migration, and has made it to a decent forest stand in Central America. She is finally able to begin making a living in her first nonbreeding season.
Even before humans were around, first-year female songbirds did not have forest ecology in their favor. They are at the bottom of the passerine social hierarchy; in addition to competition between species for resources like food and territory, our female must compete with aggressive adult males, cunning adult females, and other youngsters as desperate and inexperienced as herself. As a result of this hierarchy, she ends up with some of the lowest quality forest available, pushed all the way to the dry and nutrient-deficient forest edge, a landscape quite alien to her. With the addition of human life, what was once a sprawl of rainforest that provided plenty of remaining territory for her has been replaced with a sprawl of farmland and rural communities. With so much of the necessary nonbreeding habitat destroyed, our female is now subject to new challenges to which she is not adapted. She experiences a sparsity of the food that would be easily found deeper in the jungle. Now in a more open area, she comes into contact with new predators in greater numbers, and is more vulnerable to them under the scattered cover. And possibly worst of all, she comes into contact with neurotoxic pesticides. Many countries in Central and South America do not have the bans on dangerous pesticides that we do in the United States. Organochlorides and other neurotoxins used to defend crops from insect infestation have wiped out unbelievable numbers of flocking migrants such as Swainson's Hawks and Dickcissels. Our young female, five inches long at .3 ounces, barely stands a chance. Even if she isn't taken by them, pesticides often disrupt migrants' navigational senses. More vagrants for birders, but not good news for birds.
Facing malnourishment, predation, and neurotoxic pesticides, young passerines especially face an enormous problem in their wintering grounds. Many of their original high quality wintering grounds no longer exist, so more birds from the North American breeding population must make due with the smaller amount of high quality habitat; it's no wonder that more and more of the population is being pushed to the margins of their habitat. In some highly fragmented places, only the strongest adult males are getting the highest quality habitat. This puts a worrysome percentage of the breeding population in quite a precarious position. It's no wonder that it's becoming increasingly difficult to find Acadian Flycatchers, Wood Thrushes, and Cerulean Warblers!
 |
| Tropical Rainforests of the world. Rainforests yield the most biodiversity, but there are certainly other biomes that house neotropical migrants. |
So the next time you see a neotropical migrant, say, a young female Black-throated Green Warbler, think of the grand cycle and natural drama it has participated in. Think of the tens of thousands of miles it has flown, and all of the challenges it has faced. Think of how lucky that individual is to be living. It is sometimes said that 40% of the North American breeding songbird population has been lost since the 50's, with some species' populations nose-diving a frightening 80%. With the obstacles many young birds face in the tropics, it really is amazing that populations keep chugging along. So all I ask is not to take them for granted. We are blessed with the avifauna of our time, and it's a travesty to think that they may not exist for future generations.
Overall, the best we can do is to keep learning. Any observations of the birds are scientifically relevant; the more we know about them, the better we can protect them. So after we've endured the painful yet rewarding time that is winter birding and spring comes around, be sure to get out there and find some warblers! But then again, I don't have to tell you to do that, do I?
 |
| To read more about this subject, I highly recommend Bridget Stutchbury's Silence of the Songbirds, as one blog post can only touch the tip of this iceberg. Her narrative ability makes the book a joy to read, and brings the reader to an incredibly intimate understanding of these neotropical migrants. |
Sunday, 16 December 2012
How to protect your kids from brood parasites: Talk to them!
Let's do some science, shall we?
Lots of birds have problems with brood parasites, such as the cowbirds of the new world and cuckoos of the old world. Most brood parasites have adapted a faster incubation period and a faster growth period, so that they can hatch before the parasitized bird's actual eggs and either push them out of the nest, or just take all the food so the other chicks starve. However they do it, there are various solutions that birds have adapted to avoid this problem. Some kill the parasite's egg, some abandon their nest, but by far one of the most unique solutions are that of the Fairy-wrens, a fascinating group of songbirds native to Australia that could be described as chickadees plus hummingbird-level color.
A recent study has revealed that fairy-wren mothers begin communicating with their offspring before they have even hatched. During incubation, female Fairy-wrens give a sort of incubation call that, when the chicks hatch, will become a vocal password for food. Without this vocal password, the chicks will not be fed. She gives this call repetitively late in her offspring's incubation period, and is embedded in their brains when they hatch. This vocal password, then, is their begging call and is unique to each nest, so mothers always know which chicks are actually theirs, or at least which chicks they incubated. Mothers use these
Let's go through this:
The female lays and and begins incubating her eggs. The eggs typically take about 15 days to hatch, so the female waits until day 10 to start giving her incubation calls, both so that her embryonic offspring can actually hear her, and so that she doesn't spend the entire incubation period giving her nest away to predators. Timing is where the tables are turned for the early hatching bronze-cuckoos' (see left) chicks that frequently parasitize fairy-wrens' broods: bronze-cuckoos hatch after 12 days rather than 15, so they don't get nearly as much time within the egg to learn the vocal password. Without the correct vocal password, the fairy-wren parents will not feed the chick, so the brood parasite never gets fed, while the actual fairy-wren chicks, hatching three days later with the correct begging calls, are given all the food. Case closed, end of story. Suddenly, the early hatching habits of the bronze-cuckoo that were once an adaptation become a HUGE disadvantage. Cool stuff, right?
This discovery leads to a few questions, too. First off, if Fairy-wrens learn their begging calls during incubation, do they have any begging calls genetically programmed? The answer, it turns out, is no; Fairy-wren chicks develop with a blank slate, and learn everything in the egg. The significant implication here is well put by one of the researchers:
"These findings demonstrate that traits that appear to be innate, such as nestling begging calls, may actually be learned. Knowing this adds to our understanding of evolution and also has many practical implications, particularly for captive breeding and conservation biology."
This also means that if a mother's actual offspring are replaced by unrelated offspring during incubation, the mother's actual offspring will not know the correct call to be fed by their actual mother. It all depends on learning the right call. Another obvious question: how do males learn the calls? They don't participate at all in the incubation, but they still know the vocal password, so the female must communicate it in some way. The researchers in Australia had similar questions, and they found that females share the vocal password with their mates through a so-called "solicitation song". This way, there are no loop-holes in the vocal password system. Finally, we'll end with a prediction in the next step in what has now become an "acoustic arms race" between brood parasite and Fairy-wren: in order to survive, Bronze-cuckoos will have to adapt to their smaller window for learning the vocal password, by, well, learning it faster.
Whatever the cuckoo's "counter-solution", it seems the relationship between parasite and parasitized always produces fascinating discoveries. The big question now is if any species here in North America have adapted a similar system. The encroachment of farmland onto what were once eastern woodlands safe from brood parasitism has brought birds like Red-eyed Vireos, a species completely without adaptation against brood parasitism, face to face with Brown-headed Cowbirds, who like open areas more than forests. It will be interesting to see where evolution takes this conflict, and this discovery on these diminutive, color-blasted Australian songbirds gives us new insight into this process.
Have a great day, everyone.
Lots of birds have problems with brood parasites, such as the cowbirds of the new world and cuckoos of the old world. Most brood parasites have adapted a faster incubation period and a faster growth period, so that they can hatch before the parasitized bird's actual eggs and either push them out of the nest, or just take all the food so the other chicks starve. However they do it, there are various solutions that birds have adapted to avoid this problem. Some kill the parasite's egg, some abandon their nest, but by far one of the most unique solutions are that of the Fairy-wrens, a fascinating group of songbirds native to Australia that could be described as chickadees plus hummingbird-level color.
 |
| Internet photo of Superb Fairy-wrens, male and female |
A recent study has revealed that fairy-wren mothers begin communicating with their offspring before they have even hatched. During incubation, female Fairy-wrens give a sort of incubation call that, when the chicks hatch, will become a vocal password for food. Without this vocal password, the chicks will not be fed. She gives this call repetitively late in her offspring's incubation period, and is embedded in their brains when they hatch. This vocal password, then, is their begging call and is unique to each nest, so mothers always know which chicks are actually theirs, or at least which chicks they incubated. Mothers use these
Let's go through this:
 |
| internet photo of a Horsfield's Bronze-cuckoo |
This discovery leads to a few questions, too. First off, if Fairy-wrens learn their begging calls during incubation, do they have any begging calls genetically programmed? The answer, it turns out, is no; Fairy-wren chicks develop with a blank slate, and learn everything in the egg. The significant implication here is well put by one of the researchers:
"These findings demonstrate that traits that appear to be innate, such as nestling begging calls, may actually be learned. Knowing this adds to our understanding of evolution and also has many practical implications, particularly for captive breeding and conservation biology."
This also means that if a mother's actual offspring are replaced by unrelated offspring during incubation, the mother's actual offspring will not know the correct call to be fed by their actual mother. It all depends on learning the right call. Another obvious question: how do males learn the calls? They don't participate at all in the incubation, but they still know the vocal password, so the female must communicate it in some way. The researchers in Australia had similar questions, and they found that females share the vocal password with their mates through a so-called "solicitation song". This way, there are no loop-holes in the vocal password system. Finally, we'll end with a prediction in the next step in what has now become an "acoustic arms race" between brood parasite and Fairy-wren: in order to survive, Bronze-cuckoos will have to adapt to their smaller window for learning the vocal password, by, well, learning it faster.
Whatever the cuckoo's "counter-solution", it seems the relationship between parasite and parasitized always produces fascinating discoveries. The big question now is if any species here in North America have adapted a similar system. The encroachment of farmland onto what were once eastern woodlands safe from brood parasitism has brought birds like Red-eyed Vireos, a species completely without adaptation against brood parasitism, face to face with Brown-headed Cowbirds, who like open areas more than forests. It will be interesting to see where evolution takes this conflict, and this discovery on these diminutive, color-blasted Australian songbirds gives us new insight into this process.
Have a great day, everyone.
Saturday, 1 December 2012
Nutting's Flycatcher: a Big Year Birder's Dream
A Nutting's Flycatcher--Myiarchus nuttingi--recently made an appearance in the desert oasis of Bill Williams National Wildlife Refuge for the second time this year. This makes Arizona a pretty lucky state: Nutting's Flycatcher is a Code 5 (a.k.a. accidental) species in the ABA Area, meaning that the species has been recorded five or fewer times in the North American continent, and yet it has been recorded twice in the same spot in the same year! It even seems to have overwintered in this wildlife refuge, as it was first found in December of 2011, and was last found March 25th, this year. Basically, it's one of those really rare birds that make ANY Big Year that much better, including Sandy Komito's record setting Big Year of 1998 after which both the book and the movie titled "The Big Year" are based. Nutting's Flycatcher was the first rarity that Komito started with. Image that. January 1st; you start your year with a Code 5. That's good birding man.
But beyond the birding aspect of it, let's look into the biological aspects of this sighting. We'll start with a perennial birding favorite: the range map.
From this fine map--found on Cornell's Neotropical Birds--we can see that Nutting's Flycatchers are not migratory, but can infer that they probably disperse from their breeding territories when the season's brood is raised. We can also see that their range stretches up the western half of Mexico almost to Arizona, so it's not much of a stretch, one would think, for Nutting's Flycatchers to occur in Arizona. Their nonmigratory habits would account for their Code 5 status, though, because the birds just don't move around enough to make them common outside of their range. So what would draw the bird (if it is the same individual) to this wildlife refuge twice? Bill Williams National Wildlife Refuge is described as a rare desert habitat with some of the last stands of native cottonwood-willow forest along the Colorado River. This creates a rich, even lush riparian habitat that would appear attractive to neotropical migrants, and even neotropical rarities. But why didn't the bird just stay where it was? Wouldn't the bird have plenty of habitat in its actual range? There's not an easy answer to these questions as we don't know much about this individual other than its occurrence north-of-range, but the answer may be yes. During the nonbreeding season, a hierarchy develops that dictates which songbirds get which qualities of habitats, with older adult males at the top, younger males and females just below, and young females at the bottom with the lowest quality habitat. As habitat destruction and degradation continues, this hierarchy is pressured for all sorts of species, and the birds at the bottom are getting it worse and worse. This could push some of the individuals on the bottom of the scale out-of-range just to survive, so it would be interesting to see if this individual is a young female. We'll see how long this bird sticks around--we might get some experts on the job.
With every rarity, there are always tons of questions, even beyond identification. IDing Nutting's Flycatchers is a challenge in of itself; they even used to be considered the same species as the more common Ash-throated Flycatcher. Luckily, they give their distinctive callnotes frequently. But beyond that, why the bird is occurring out of range raises all sorts of questions, such as how it behaves differently when in and out of range. Sadly, the likelihood that most of these questions will be answered is slim, but that's one of the best things about birds, and nature as a whole: it puts you in a constant state of inquiry, and that's a big reason why I'll never stop.
To read more about the bird, check here and here.
But beyond the birding aspect of it, let's look into the biological aspects of this sighting. We'll start with a perennial birding favorite: the range map.
With every rarity, there are always tons of questions, even beyond identification. IDing Nutting's Flycatchers is a challenge in of itself; they even used to be considered the same species as the more common Ash-throated Flycatcher. Luckily, they give their distinctive callnotes frequently. But beyond that, why the bird is occurring out of range raises all sorts of questions, such as how it behaves differently when in and out of range. Sadly, the likelihood that most of these questions will be answered is slim, but that's one of the best things about birds, and nature as a whole: it puts you in a constant state of inquiry, and that's a big reason why I'll never stop.
To read more about the bird, check here and here.
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| Internet Photo of the Nutting's Flycatcher. Found here. |
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