Ornithologists say that climate change is having a profound effect on bird behaviour and suggest that this phenomenon can act as an early warning system to the dangers posed to Earth.
‘’The fact that birds are changing their behaviour means that climate is changing already,” says Marco Lambertini, chief executive of Birdlife International (BI), a conservation federation working to protect birds and their habitats. ‘’Birds are an excellent early warning system to what is happening to climate.’’
Numerous studies have been tracking the effects of climate change on the survival, migration and reproduction of different bird species. As spring temperatures rise, the breeding of Ficedula flycatcher has been delayed across Europe. The same reason was attributed to earlier breeding by Tree swallows in North America and an opposite tendency in Antarctic sea birds.
“Some are winners, some are losers. Some species will expand, some species will run out of habitat,” said Lambertini, speaking with IPS on the on the sidelines of the annual Bird Watching Conference in Tel Aviv, last month. “But it’s estimated that for each species that benefits, three species will be in trouble,’’ he said.
While climate change related threats to human livelihood might seem clear, the other consequences for man are not too obvious. “We still need to consider the intrinsic value of nature, its spiritual, aesthetic, emotional and recreational values which are as important as its economic value,” said Lambertini.
‘The Economics of Ecosystems and Biodiversity,’ a recently published study aimed at setting a price tag on Earth’s natural assets, considers the avian aspect. Insectivorous birds, according to the study, play an important role in crop production as they regulate insect pests.
“Maybe people are not aware of it, but the situation is quite acute,” says Prof. Marcel Visser, who heads the animal ecology department at the Netherlands Institute of Ecology. “There are already many species which are declining quickly,’’ he told IPS over telephone.
A study by Visser published last year found that 12 out of 24 European bird species studied have decreased their migration distances through the past 70 years. “There’s always a lot of variation. It’s not that all the species change in the same way.”
Another study conducted by Durham University scientists projects that by the end of the century nine out of the 17 European birds studied may actually be undertaking longer journeys northwards.
One key element is food availability. Alterations in weather patterns directly affect the timing of vegetation growth and the birds that feed on it or on the insects they eat. In many cases, bird migrations are no longer synchronised with food abundance.
Other factors that are known to be challenging bird survival on land and sea include prey distribution and shrinking habitats.
“They need to adapt themselves,’’ says Yoram Yom-Tov of the Tel Aviv University, who found some bird species in England to be changing their body weight. “Those who don’t adapt – their numbers decline, those who do – their numbers remain stable or even increase.”
When it comes to projecting the risks birds face, ornithologists avoid numbers. “It all depends on how our climate is going to change. If the temperature is going to rise by two degrees the patterns will be different from when temperature rises by four degrees,” says Visser.
BI currently ranks climate change a distant ninth among the different threats to birds, and issued a formal position on climate change only in June 2008. “Some conservation movements – and BI is probably part of it – have woken up late to the challenge. But I think we are pretty much on course to fight it very hard,” Lambertini told IPS.
Conservation measures targeted at particular bird species are not the way to deal with the threat posed by climate change, says Visser. ‘’The only thing that can be done is reduce greenhouse gas emissions and make sure the temperature doesn’t increase by more than, say, one or two degrees.’’
BI – which has affiliates in more than 100 countries – believes that some mitigation measures are inappropriate. “Badly placed wind farms, unsustainably produced biofuels and harmful irrigation and anti-flood measures are posing new threats and stresses on birds and their habitats too,” a position paper by the organisation reads.
“We don’t object to wind farms. We want wind farms to be located in places which are not impacting biodiversity,” Lambertini explained.
Similarly while sea-level rise poses a threat to both coastal human communities and low-lying ecosystems, inadequate barrier construction could put shore birds at risk. “Flood defence is something that we have to do, but we support prevention rather than firefighting,” says Lambertini. “If we don’t tackle the root problem we will need bigger and bigger defences – it’s not feasible.”
A study published last year by researchers from three universities in Canada and the United States found that male mockingbirds in more variable climates sing more complex tunes.
Mockingbirds sing to attract mates, and the complexity of the chanting may indicate the quality of the singer. But although finer tunes are thought to help the feathered troubadours adapt better to harsher climes, the accelerating rate of change could mean the birds are singing their own requiem.