Declining rainfall, bugs, and birds

Via Eurekalert

Smithsonian scientists find declining rainfall is a major influence for migrating birds

This is a male American redstart. Credit: Dan Pancamo

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.

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anna v

Such presumption that correlation is causation, as always in these climate studies.
We have migrating swallows in my area of Greece. They leave in October and return in the spring. Tradition has it that they return in March, even folk poems say so. I have not seen my first swallow yet. Does that mean it has been wet in Egypt?
Storms can destroy swarms. One October, driving in Crete I had to stop because the road surface was alive with swallows drying in the sun. A storm had passed and threw them to the ground. The ones that were over the sea would have drowned.
I would think that the birds would gauge the weather, probably sensing highs and lows, and time their departure with that. Storms can really drown them in the sea . There would be a correlation with wetness, they will leave early if it is dry, to get the good weather, which is another possible hypothesis/ factor entering in this correlation.

LeeHarvey

“Making the future even more dire, climate models predict not only increased warming on temperate breeding areas but also continued drying in the Caribbean.”
It sure was lucky that the Beagle happened to land in the only island group on the face of the earth that has variable local conditions, or else Darwin might never have noticed that species are capable of adaptation to geography and climate. [/sarc]

Clive

“Delaying departure could be beneficial ” … Beneficial because it has been so damn cold here in western Canada these past few springs that LBJs and SSBs that arrive early are killed by snow and cold. Snow and cold was so bad last year we lost over 90 percent of our Canada goose crop (eggs and goslings) on the ponds across the road from my house. Hardy geese!
And the robins will get hammered again this weekend by big snow dump!
I liked the old, warmer version of GW much more the colder version of warming … and I know the birds do as well.

LeeHarvey

@anna v:
Are those African or European swallows?

ew-3

My head is spinning.
This report is based on the notion that climate warming is causing declining rain.
But last week someone explained all that extra snow we got this year was because climate warming caused MORE water vapor in the atmosphere which produced more snow.

Mike M

anna v – Good point. Whenever I’m planning a flight the anticipated weather en route is always the deciding go/no-go factor.

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.

Too bad that the birds were not flying sooner because then they could have just blamed global warming directly instead of having to resort to this kind of stretch.

D Caldwell

Wow!
Changes in environmental conditions might cause changes in the behavior of migrating birds.
This is, indeed, incredibly insightful!

Jim G

“Researchers have focused on how warming trends in temperate breeding areas disrupt the sensitive ecology of migratory birds.”
Not unless they are breeding in the heat sink cities. Of course “climate disruptions” can be blamed for changes in rainfall as well. Chalk another one up to CO2. It will never end until we take away the research funding.

Walter Schneider

From the main article:

Climactic warming, however, is causing declining and more variable rainfall cycles in many areas…

Right, can’t have a study like that without mentioning a climax…and the climax is now history?
It sure is a good thing that birds who live on insects know how to get around by flying from a declining source of food to a more plentiful one. I would think that a few hundred kilometers here or there is by far not as much a problem for such birds as is their twice-annual migration of a few thousand kilometers.
Did the study examine that? Perhaps it was just a bit too cozy for the researchers to go into more rainy areas to check that out. After all, they would have become all wet doing that.

Amount of rainfall is a strictly local affair.
http://www.vukcevic.talktalk.net/Oxbridge.htm
Oxford and Cambridge are only 65 miles apart.

George E. Smith

Wow, they say life began on earth 4.5 billion years ago, and so far everything has been fine.
It’s so sad to think that global climate disruption will bring that all to a close.

James Sexton

Declining rainfall?????
Impossible. We were just told this winter a warmer climate means a wetter climate.

Stephen Rasey

This is just a guess, but an educated one, that somehow these birds survived the last ice age and the warming that followed it.
Maybe these ecologists issuing alarms are really Creationists at heart. Perhaps they think the World was created 6000 years ago just as it was in 1940 before we humans commited original sin through postwar industrializaiton. It would explain a lot.

DJ

“…During the past 16 years, the dry season in Jamaica has become…”
And the 16 years before that it was “normal”????
What about the 16 years before that, before that, before that….ad infinitum???
It sounds like we’re basing hysteria on a remarkably brief 16 year period, without mentioning an particular 16 year period in history with similar observations, and once again, the Models are like alarm sirens, but with no quantifiable reference, and no input of land use or other normal climate variation.
A critical question for scientists is whether this variation carries consequences???
Ya think?? The critical question should be how the birds have adapted in the past to shifts that were very likely much more severe, and part of the natural variability of climate.
Then go on to quantify exactly how much of the current change is anthropogenic….IF any.

chris b

An 11% decline in precipitation over 16 years does not sound like anything but normal variability.
If this species is vulnerable to that sort of decline in precipitation it would have been extinct long ago.

Dave Wendt

“The scientists observed the redstarts in their non-breeding territories for five years during the dry season. ”
Five years? Well that’s all settled then. This paper suggests precipitation patterns in Jamaica may be just a tad more complicated than these folks seem to assume.
http://people.uncw.edu/gambled/2008gamblecurtis.pdf

Teresa

Wow. Its almost like over thousands of years mother nature may have evolved a system where the birds will not migrate to their breeding grounds as quickly and therefore may have reduced winter #’s when drought may reduce the available food the next winter. Something must be done to overcome this immediately or we will lose traction of humans can control everything on the planet.

Dr. Dave

“Making the future even more dire, climate models predict not only increased warming on temperate breeding areas but also continued drying in the Caribbean.”
__________________________________________________
I was waiting for the global warming hook and they didn’t disappoint. Twenty years ago this would have just been an interesting biological observation. Today it can be passed off as a “significant finding” because of the threat of global warming. Then they had to repeat was “climate models predict”. Perhaps I’m cynical, but bird watching in Jamaica during the winter doesn’t seem like a bad gig. Obviously “more study is needed”.
You just know that AGW was worked into the grant proposal for this study.

DesertYote

So the birds have evolved the ability to sync their life cycle with a varying climatically regime. Why would they have done that? Either they anticipated mankind changing thins, or (now don’t laugh) maybe the climatic regime is naturally variable.

Algebra

Climactic warming?

DesertYote

BTW “Smithsonian” and “Scientist” don’t belong in the same sentence.

jack morrow

Gosh-another “team” finding of a dire problem due to (term now not used) global warming. It never ends. No humming birds in my area of S. Ala. yet. Is it wet or dry in S. America where they migrate from or do they know the weather up in the states is still too cold for them yet. A friend of mine sailing in the middle of the Gulf of Mexico had a flock of them rest on her sailboat masts on their way somewhere in the fall . They must have been taking a shortcut across the Gulf instead of going across Central America. I propose a new study(fully funded of course) to look into the path of humming birds and I think somewhere in the Keys would be a great place for “team” headquarters and only a 5 year study for the “team” to start sounds about right.

Robert M

“Making the future even more dire, climate models predict not only increased warming on temperate breeding areas but also continued drying in the Caribbean.”
Really, a model predicts increased warming, and continued drying? Well it must be true… Until is isn’t, but then of course a new model will surface that predicted that very thing the whole time…
Of course, all the money spent on demonizing a trace gas, that if it was eliminated would kill us all is beside the point. I wonder how many studies there have been about the harm that progressive policies cause by diverting resources away from real world problems.

ferdberple

Billions of tax dollars down the drain to show migratory birds can predict climate better than climate models.
These migratory birds produce huge volumes of CO2 in relation to their size during their annual migrations. We need to tax this CO2 and thereby reduce the unnecessary migration, to slow the rate of climate change in Jamaica.
Like people, birds should not be allowed to cross borders without passports and proof of resources. They are fair-weather freeloaders. Traveling here without permission and taking the food from our local birds. It is high time someone built a fence and kept them back where they belong.

It’s an indecreasing floodrought! Run! Stand still! Go backwards! Go south! Go north! Burrow deeper! Fly higher! Turn inside out! Apply the precautionary principle and do everything at once while doing nothing at all!

Philip Finck

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?

Latitude

“Climactic warming, however, is causing declining and more variable rainfall cycles in many areas”
———————————————————————————————–
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.
=======================================================
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
=====================================================
You just can’t win………………………………………………………….

jack morrow

Polistra says
Very funny-I’m now book-marking your blog.

ferdberple

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.

Stephen Brown

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’.

Rob R

Fred Berple
Why would one let the truth get in the way of a lucrative narrative?

DJ

Polistra…
“…It’s an indecreasing floodrought…”
Can I use that????

Jimbo

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.

pat

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.

Gary Pearse

“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!

Stephan

What is happening to the great USA?

Mac the Knife

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.

Tenuc

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!

Jimbo

Making the future even more dire, climate models predict not only increased warming on temperate breeding areas but also continued drying in the Caribbean.

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

Jimbo

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.

James Allison

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.

BigWaveDave

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]

u.k.(us)

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.”

Mac the Knife

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!

alan

“climate models predict”…bla,bla,bla,bla. It’s worse than we thought.

el gordo

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.

Jimbo

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)

ShrNfr

This research is for the birds.

ChrissyStarr

@LeeHarvey
“Huh, Uh, I don’t know that!” (gets cast off into the gorge of eternal peril)

LeeHarvey says:
April 1, 2011 at 12:29 pm
@anna v:
Are those African or European swallows?

Sorry, I can’t resist.

http://www.youtube.com/watch?v=4b4bGAoVR7g