July 7, 2010

Bird News

Filed under: Adaptation, Animals

We hear over and over that climate change is now so rapid that ecosystems all over the world are in peril as they attempt to cope with changes to the environment. This view of “delicate” ecosystems is at odds with the reality of the long climate history of the Earth. The climate has warmed in the past, cooled in the past, and many of these changes were quite rapid. Delicate ecosystems would have disappeared long ago and the most robust systems would have survived.

Birds are particular well-suited to move as conditions change. Somewhere deep in their DNA is a memory of changes in the past and how to cope with those changes. Four articles have appeared recently reminding us that birds are fully capable of responding to change in climate.

Europeans have been observing bird behavior for centuries, and in the Volga-Kama region of the Tatarstan Republic of Russia, observations go back to 1811 AD. The Tatarstan skylarks migrate south for the winter and their return is a traditional harbinger of spring in Northern, Central, and Eastern Europe. A team of scientists from Tatarstan Republic and the United Kingdom examined the long record of return dates of the skylark and noticed that they have been arriving earlier and earlier over the past three decades (11 days earlier since the late 1970s). Askeyev et al. showed that the trend in bird behavior occurred when the March air temperatures in the region have increased by 3.7ºC. The climate changes, the birds respond. C’est la vie. We note that the birds don’t appear to be victims of changes in temperature – they’ve appropriately adapted their behavior to fit ever-changing conditions.


Tatarstan skylark (Alauda arvensis)

A similar story can be found in a recent article in the Journal of Ornithology in which attention was placed on climate change and the Great Reed Warbler in Poland. Dyrcz and Halupka collected breeding data on the birds over a study period extending from 1970 to 2007; the birds were studied near fish ponds in southwestern Poland that are part of the “Stawy Milickie” nature reserve. They noted that over the study period, the May to July (the months of egg laying) temperatures in the area had increased by 2.2ºC. As the temperatures warmed, the birds moved up egg laying by nearly two weeks. They note that “We did not detect any effect of ambient temperature on clutch size, length of laying period, nest losses and production of fledglings per nest.” They conclude “In summary, it seems that so far the Great Reed Warbler has adapted well to climate change by shifting the timing of breeding, but not changing other parameters of breeding biology. The studied population does not benefit from climate warming (as was found in Bavaria), but apparently does not suffer. Hence, the results of this study do not confirm the prediction…that long-distance migrants would suffer due to climate change.”

Great Reed Warbler (Acrocephalus arundinaceus)

A similar study was carried out in eastern Poland dealing with four different varieties of sedentary birds, which because they do not migrate, they might be more vulnerable to changes in climate. Wesołowski and Cholewa studied the birds within Poland’s Bialowieza National Park (BNP) which provides nearly pristine conditions in terms of little anthropogenic alterations. They collected data on the various birds over the period 1975 to 2007, and they indeed found a significant warming during the spring of over 1ºC. The authors caution that “However, it must be stressed that the climate in the Bialowieza region seems to be fluctuating without a clear warming trend when investigated over a longer time period. Two warmer than average periods were discernible within a 215 year series (1780–1995), namely years 1820–1870 and the current time period from 1970 onwards.” They too found that the birds breed earlier as spring temperatures warm, and they state “As all the bird species studied in BNP were phonologically plastic and strongly responded to rising spring temperatures by breeding earlier, they were behaviourally and physiologically equipped to adjust phenotypically and are probably able to adjust to much stronger climate warming than observed at present.” Once again, the birds are found to be well-equipped to handle changes in climate.

A fourth recent study on birds and climate changed was conducted by three scientists from New York and their results appeared in Global Change Biology. Zuckerberg et al. state that “We used the New York State Breeding Bird Atlas, a statewide survey of 5332 25 km2 blocks surveyed in 1980–1985 and 2000–2005, to test several predictions that the birds of New York State are responding to climate change.” They noted that the New York area warmed over 1ºC between the two survey periods and accordingly, they predicted that the birds would have moved poleward and to higher elevations. The three scientists report “As expected, we found all bird species (n = 129) included in this analysis showed an average northward range shift in their mean latitude of 3.58 km.” However, they found “Counter to our predictions, and the results from other studies and models, we did not find a general pattern of species moving to higher elevations.”

All of these studies remind us that the birds have been around a very long time, they have experience massive changes in climate over the eons of their existence, they have learned how to adapt to warmer and colder conditions - they are not going to sit idly by and become victims of the global warming.

References:

Askeyev, O.V., T.H. Sparks, and I.V. Askeyev. 2008. Earliest recorded Tatarstan skylark in 2008: Non-linear response to temperature suggests advances in arrival dates may accelerate. Climate Research, 38, 189-192.

Dyrcz, A., and L. Halupka. 2009. The response of the Great Reed Warbler Acrocephalus arundinaceus to climate change. Journal of Ornithology, 150, 39-44.

Wesołowski, T., and M. Cholewa. 2009. Climate variation and bird breeding seasons in a primeval temperate forest. Climate Research, 38, 199-208.

Zuckerberg, B., A.M. Woods, and W.F. Porter. 2009. Poleward shifts in breeding bird distributions in New York State. Global Change Biology, 15, 1866-1883.




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