Via Eurekalert
Smithsonian scientists find declining rainfall is a major influence for migrating birds
Instinct and the annual increase of daylight hours have long been thought to be the triggers for birds to begin their spring migration. Scientists at the Smithsonian Conservation Biology Institute, however, have found that that may not be the case. Researchers have focused on how warming trends in temperate breeding areas disrupt the sensitive ecology of migratory birds. This new research shows that changes in rainfall on the tropical wintering grounds could be equally disruptive. The team’s findings are published in scientific journal Proceedings of the Royal Society B, March 30.
Many of the bird species that breed in the temperate forests, marshes and backyards of North America spend the winter months in the tropics of the Caribbean, and Central and South America. Insects are the primary food for many birds during the winter, and rainfall largely determines the amount of insects available. Climactic warming, however, is causing declining and more variable rainfall cycles in many areas, affecting the availability of insects and delaying when birds leave for their northern breeding grounds. To examine this, the Smithsonian scientists focused on American redstarts (Setophaga ruticilla), a member of the warbler family, at a non-breeding site in Jamaica where they conduct long-term studies.
“American redstarts were a perfect species for this study since they defend exclusive territories throughout the non-breeding period until they depart for spring migration and most return back to the same territory the following year,” said Pete Marra, research ecologist at the Smithsonian Conservation Biology Institute’s Migratory Bird Center. “These behaviors made it relatively easy to keep track of individual birds over multiple years and document changing spring departures. Each individual was fitted with a unique combination of colored leg bands.”
Precipitation in Jamaica is highly seasonal, with consistent rainfall from September to November and a pronounced dry season from January to March. The scientists observed the redstarts in their non-breeding territories for five years during the dry season. They paid special attention to the annual variation in dry season rainfall. The correlation between the amount of insects in a bird’s territory and the timing of its departure suggested to the team that annual variation in food availability was an important determining factor in the timing of spring migration. Had the redstarts relied on internal cues alone to schedule their spring departure, they would have all left their winter territories at the same time each year.
“Our results support the idea that environmental conditions on tropical non-breeding areas can influence the departure time for spring migration,” said Colin Studds, a postdoctoral fellow at the Smithsonian Conservation Biology Institute’s Migratory Bird Center and lead author of the study. “We found that the same birds changed their spring departure from one year to the next in relation to the amount of rainfall and food in March.”
During the past 16 years, the dry season in Jamaica has become both increasingly severe and unpredictable, leading to an 11 percent drop in total rainfall during the three-month annual drought. Making the future even more dire, climate models predict not only increased warming on temperate breeding areas but also continued drying in the Caribbean.
A critical question for the scientists is whether this variation in the onset of spring migration carries consequences for the birds. Delaying departure could be beneficial if food resources are low and the individual has not yet stored enough energy to migrate. However, delaying departure could affect arrival time to its breeding territory and result in less time to successfully reproduce. “Because American redstarts return to the same site to breed each year, arriving later may make it harder for them remain to remain in synch with their breeding cycle,” Studds said.
Climate models predict for Jamaica …….. hold it. Climate models are utterly useless in regional predictions given their accuracy. I thought that this was generally agreed by all?
“Climactic warming, however, is causing declining and more variable rainfall cycles in many areas”
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Article:
As Predicted, Global Warming Fuels More Tropical Rainfall
Scientists had predicted that global warming ought to increase rainfall in the tropics. Now NASA researchers say it has.
Scientists assembled a 27-year global record of rainfall from satellite observations and ground-based instruments and found that the rainiest years between 1979 and 2005 occurred primarily after 2001.
The wettest year in the record was 2005, followed by 2004, 2003, 2002 and 1998.
The patterns observed in the record showed that increases in rainfall were concentrated over tropical oceans, while there was a slight decrease over land.
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Tropical Atlantic sees weaker trade winds and more rainfall
“Accompanying these changes in wind and ocean temperature is a very significant increase in rainfall, ”
=======================================================
TROPICAL WARMING BRINGING MORE FLOODS
A satellite study of tropical rains since 1980’s has shown a trend of more frequent flash floods and tropical downpours confirming computer model predictions of more cloudbursts due to human-made burning of fossil fuels.
Results of the study have been published in the journal Science and revealed extreme soakings were greater than most predictions.
The findings were based on a study of the tropical oceans, where satellites can more easily record rainfall. These trends were likely to be matched over land
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You just can’t win………………………………………………………….
Polistra says
Very funny-I’m now book-marking your blog.
The Smithsonian study is bogus. They obvious did not take the time to check their facts:
METEOROLOGICAL SERVICE JAMAICA
CLIMATE BRANCH
PRELIMINARY MONTHLY RAINFALL SUMMARY FOR
FEBRUARY 2011
A comparison of the old 30 year mean (1951-80) with the 1971-2000 mean by the
Meteorological Service has shown that the island’s rainfall patterns and values have not changed significantly for the current thirty-year (1971-2000) period. The main changes noted are that of wetter dry periods and drier wet periods. This has however not affected the overall rainfall pattern for the island.
http://www.metservice.gov.jm/documents/documents/RainfallSummaryFebruary2011.pdf
In contrast, here is what the Smithsonian “scientists” wrote:
“During the past 16 years, the dry season in Jamaica has become both increasingly severe and unpredictable, leading to an 11 percent drop in total rainfall during the three-month annual drought. Making the future even more dire, climate models predict not only increased warming on temperate breeding areas but also continued drying in the Caribbean.”
Notice that Jamaica says the dry periods are getting wetter, while the Smithsonian says the dry periods are getting dryer.
This is garbage.
We know little or nothing about what precipitates bird migration or how the birds navigate.
There’s a lot of speculation but very little evidence.
Whether or not the food supply for the birds is present upon their migratory arrival is simply happen-stance. Prime birds will survive. Less than prime birds will die.
It’s called ‘Nature’.
Fred Berple
Why would one let the truth get in the way of a lucrative narrative?
Polistra…
“…It’s an indecreasing floodrought…”
Can I use that????
Here is some peer reviewed research on bird migrations and climate change.
Bird migrations longer
Bird migrations shorter
Bird migrations disturbed
I suppose after the few NH winters things might be getting back to normal.
Maybe the birds can try out California or Hawaii where global warming has brought a great deal of rain. And at least in Hawaii, insects.
BTW. The relationship between rain and insects is not direct. You need substantial rain fall, say a quarter to an inch, with an intervening dry spell of 3 days to a week. More rain can indirectly kill larvae. Nor does the total rain matter much.
“The scientists observed the redstarts in their non-breeding territories for five years during the dry season.”
“………… arriving later may make it harder for them (remain) to remain in synch with their breeding cycle,” Studds said.
Five years of individual bird study at both ends and it only “MAY” make it harder. Well did it or did it not?How much delay was there on average over the five years. Did you note if one or two did have a bad time of it up north? Do all studies in climatology these days (or horrors! all sciences) start off with a presumption that has to be upheld. This study should have said, “So far the jury is still out on our hypothesis and we don’t yet know if anything other than instinct and the annual increase of daylight hours are the triggers for birds to begin their spring migration. We scientists at the Smithsonian Conservation Biology Institute have (not) found that that may not be the case.”
This is all in a day for a University TA but the Smithsonian needing this critique!
What is happening to the great USA?
The Smithsonian scientists studied one particular subspecies of birds for 5 years, in a geographically very specific area of Jamaica, specifically during the 3 month long Jamaican dry season.
They found that the little birds departure flight schedule from Jamaica is more consistent when it rains more and their bug food is plentiful. It may be more variable when it is drier and bug food is in short supply in Jamaica.
From this, and a supporting cast of computer climate models (Ugh..), they conclude that AGW is ‘making the birdies future more dire’ because it may screw up their departure timing to travel from Jamaica up to their summer breeding grounds in the temperate forests and marshes of Wisconsin. To say this is ‘a stretch’ is a profound understatement!
A concentrated migration flight of the majority of the Redstarts may expose their numbers to catastrophic risk from single events like tropical storms. A more distributed over time migration may in fact be quite beneficial to population stability and over all breeding success!
It could equally be argued that, if AGW was a real phenomena, the summer breeding season in the temperate forests and marshes of Wisconsin (and all of the norther tier states and Canada) would be beneficially extended, allowing the little birdies to be more successful in their breeding and fledging of many more Redstarts!
Additionally, 5 years of data is an insufficient baseline to draw any meaningful conclusions about regional variations in Jamaican weather on the breeding success and long term population stability of Redstart migrations from Jamaica to Wisconsin.
Finally, all of the hyperbole embedded in this study can be adequately summarized as simply ‘Evolution In Action’. If the little Redstarts are adaptable (and I’m betting they are!), they will continue to adapt to regional variability in weather and continue to be successful breeders in the northern marshes and temperate forests. If they can not adapt, they will become extinct, as 99.9% of all animals that ever existed on the planet have over the last millions of years of earthly biosphere evolution.
Think of it as Evolution In Action, because that is exactly what it is. The weather, climate, atmosphere, oceans and land masses on this dynamic planet are constantly and naturally changing. There is no Perfect Stasis. There is no Ideal Condition. There is only continual change. All of the animal species and all other biota on this planet must continually adapt to these natural environmental changes…. or perish. That’s the way it works, naturally.
The endless pseudo-scientific drivel continues. Looks like the Smithsonian is yet another bastion of science that has fallen by the wayside. Don’t these people realise just how foolish these sort of conclusions make them look!
The thing that has kept this farce going on for so long is lovely research funding, power hungry politicians and greedy scammers investing in carbon projects.
Climate models and climate scientists also predict drywet.
Sahel to get less rain
Sahel to get more rain
Sahel may get more or less rain
UK may get more droughts
UK may get more rain
Stephen Brown says:
April 1, 2011 at 2:22 pm
This is garbage.
…………………….
It’s called ‘Nature’.
Perhaps survival of the fittest is more apt. Birds have been around much longer than humans and can adapt.
The more funding that goes into climate science the more nonsense we get churned out. These people go out to the field looking for evidence to confirm their beliefs. This has become a religion and it’s a travesty.
Does the extra CO2 in the atmosphere make air denser? If so then the redstarts migratory flight times will likely be affected. Surely further vital research needs to be done on this.
Now that we have shown how bad global warming can be by looking at whats happening to the birds in Jamaica, ‘mon. we need to see if there are similar effects in Amsterdam and Lisbon, too. [/sarc]
What do I know, but:
http://identify.whatbird.com/obj/558/overview/American_Redstart.aspx
Shows of a map of the birds migratory extent, which includes a lot more than Jamaica, and includes this excerpt:
“Due to the extensive population of this species of bird, it has received an evaluation rating of Least Concern.”
polistra says:
April 1, 2011 at 1:54 pm
Thanks! That put a big grin on my face, this fine Friday afternoon! Really – too funny!
“climate models predict”…bla,bla,bla,bla. It’s worse than we thought.
During the long drought in Australia the birds stayed away, but now that the rains have returned they are here in abundance.
http://www.abc.net.au/local/audio/2011/03/28/3175810.htm
We are simply amazed by their inbuilt knowledge on the subject of when and where to breed.
I wonder why the Smithsonian scientists studied Jamaica? Would it have anything to do with its great beaches? Crystal clear waters? Rum? Warmth? Carefree semi-holiday? Why didn’t they look at birds in Chad? I picked the wrong career. ;O)
This research is for the birds.
@LeeHarvey
“Huh, Uh, I don’t know that!” (gets cast off into the gorge of eternal peril)
Sorry, I can’t resist.
http://www.youtube.com/watch?v=4b4bGAoVR7g