unimaginative2
Senior Member
Where have all the barn swallows gone?
NICOLE BAUTE
DAVE CARTER, GUELPH MERCURY
Antonio Salvadori catches a barn swallow in a net in a barn in the Guelph area yesterday as part of a barn swallow study he's conducting.
The Record
GUELPH (Jun 1, 2007)
Antonio Salvadori bends a tiny metal band with a pair of needle-nose pliers. The barn swallow in his hand is still, and it barely fights as Salvadori lifts her tiny leg and slides on the band before releasing her into the open air.
"OK, baby, off you go," he said, turning to make a note on a clipboard in the trunk of his car.
Salvadori is tracking barn swallows in 15 barns in Guelph and Wellington County, part of an early effort to determine why the barn swallow population in Ontario has declined by 35 per cent in the last 20 years.
The shocking figure is one of many gathered during a five-year province-wide survey the Ontario Breeding Bird Atlas, 2001 to 2005 currently being summarized at the University of Guelph for fall publication.
"It's not a mystery so much,"said Salvadori when asked about the declines. "With changing environments, the populations are suffering. There's no doubt about it."
A full-time bird bander, the retired professor was one of 2,500 volunteers collectively logging 150,000 hours of fieldwork during the study.
When the startling numbers for barn swallows started to come in, Salvadori set to work on his own in the Guelph area, planning to follow the birds closely over a long period of time in hopes of finding some answers.
So far, he has none. In some barns, like the big, beige one he worked at yesterday afternoon, it's obvious the swallows are flourishing. But elsewhere he has seen some troubling signs.
"I've been to some farms where some farmers are actively destroying the nests of some swallows" because they're pests, he said..
"Is that causing the phenomenal decline that's taking place?"he asks."I don't know."
The barn swallow is one of six species of swallows small, flying-insect-eating, "open country"birds common in Guelph and southwestern Ontario that have experienced significant population declines in the last 20 years.
Since the last Ontario Breeding Bird Atlas survey, from 1981 to 1985, cliff swallows experienced roughly a 50 per cent population decline. Bank swallows and purple martins are close behind them with 45 and 46 per cent declines, and rough-winged and tree swallows are down 29 and 17 per cent, respectively.
Project co-ordinator Mike Cadman explains the numbers are not based on population figures, which would be nearly impossible to track, but rather on the "possibility of finding the bird in 20 hours of effort."
While the survey doesn't seek to answer why this is happening, Cadman and his colleagues are aware of many possible reasons.
He said before human habitation, these birds nested solely in cliffsides, sand banks and hollow trees.
But when we arrived, with our barns and birdhouses, gravel pits and picnic shelters, new nesting spots flourished for many of the bird species in southern Ontario, and their populations grew.
The interdependence that followed was fine until humans started changing their architectural and farming practices.
"Over time we've come in and cleared most of North America, we've opened up habitats for those birds and artificially helped their populations expand," Cadman explains.
"They become so dependent on these structures. And when we change these structures, of course, it leads to big problems for the birds."
For example, fewer old-style barns with big, open doors might leave swallows circling for new place to roost, if they can find one.
To further explain the phenomenon, Cadman refers to the chimney swift, aptly named for its penchant for nesting in chimneys. Its population has declined by 46 per cent in the last 20 years, which Cadman attributes, quite simply, to changes in chimneys. People cap or close them up, leaving the chimney swifts homeless.
Grassland birds such as the upland sandpiper and the bobolink are also experiencing a significant population decline. Cadman said this could be because of the ongoing conversion of meadows and grasslands into field crops, resulting in a significant decline in the flying insect populations necessary for their survival.
Cadman said this may also be influencing the swallow populations. Likewise, fewer livestock farms means fewer locales with a jackpot of insect feasts.
Another culprit could be crop pesticides, which may kill flying insects, the weeds that nourish flying insects, or the birds themselves.
Or it could be climate change, which has already caused one hurricane that sent birds back north to our chilly country before the weather had changed.
The possibilities are endless.
Cadman said he hopes the forthcoming book, expected to be published in September, will be the beginning of extensive research on these birds, their habitats and their livelihood.
NICOLE BAUTE
DAVE CARTER, GUELPH MERCURY
Antonio Salvadori catches a barn swallow in a net in a barn in the Guelph area yesterday as part of a barn swallow study he's conducting.
The Record
GUELPH (Jun 1, 2007)
Antonio Salvadori bends a tiny metal band with a pair of needle-nose pliers. The barn swallow in his hand is still, and it barely fights as Salvadori lifts her tiny leg and slides on the band before releasing her into the open air.
"OK, baby, off you go," he said, turning to make a note on a clipboard in the trunk of his car.
Salvadori is tracking barn swallows in 15 barns in Guelph and Wellington County, part of an early effort to determine why the barn swallow population in Ontario has declined by 35 per cent in the last 20 years.
The shocking figure is one of many gathered during a five-year province-wide survey the Ontario Breeding Bird Atlas, 2001 to 2005 currently being summarized at the University of Guelph for fall publication.
"It's not a mystery so much,"said Salvadori when asked about the declines. "With changing environments, the populations are suffering. There's no doubt about it."
A full-time bird bander, the retired professor was one of 2,500 volunteers collectively logging 150,000 hours of fieldwork during the study.
When the startling numbers for barn swallows started to come in, Salvadori set to work on his own in the Guelph area, planning to follow the birds closely over a long period of time in hopes of finding some answers.
So far, he has none. In some barns, like the big, beige one he worked at yesterday afternoon, it's obvious the swallows are flourishing. But elsewhere he has seen some troubling signs.
"I've been to some farms where some farmers are actively destroying the nests of some swallows" because they're pests, he said..
"Is that causing the phenomenal decline that's taking place?"he asks."I don't know."
The barn swallow is one of six species of swallows small, flying-insect-eating, "open country"birds common in Guelph and southwestern Ontario that have experienced significant population declines in the last 20 years.
Since the last Ontario Breeding Bird Atlas survey, from 1981 to 1985, cliff swallows experienced roughly a 50 per cent population decline. Bank swallows and purple martins are close behind them with 45 and 46 per cent declines, and rough-winged and tree swallows are down 29 and 17 per cent, respectively.
Project co-ordinator Mike Cadman explains the numbers are not based on population figures, which would be nearly impossible to track, but rather on the "possibility of finding the bird in 20 hours of effort."
While the survey doesn't seek to answer why this is happening, Cadman and his colleagues are aware of many possible reasons.
He said before human habitation, these birds nested solely in cliffsides, sand banks and hollow trees.
But when we arrived, with our barns and birdhouses, gravel pits and picnic shelters, new nesting spots flourished for many of the bird species in southern Ontario, and their populations grew.
The interdependence that followed was fine until humans started changing their architectural and farming practices.
"Over time we've come in and cleared most of North America, we've opened up habitats for those birds and artificially helped their populations expand," Cadman explains.
"They become so dependent on these structures. And when we change these structures, of course, it leads to big problems for the birds."
For example, fewer old-style barns with big, open doors might leave swallows circling for new place to roost, if they can find one.
To further explain the phenomenon, Cadman refers to the chimney swift, aptly named for its penchant for nesting in chimneys. Its population has declined by 46 per cent in the last 20 years, which Cadman attributes, quite simply, to changes in chimneys. People cap or close them up, leaving the chimney swifts homeless.
Grassland birds such as the upland sandpiper and the bobolink are also experiencing a significant population decline. Cadman said this could be because of the ongoing conversion of meadows and grasslands into field crops, resulting in a significant decline in the flying insect populations necessary for their survival.
Cadman said this may also be influencing the swallow populations. Likewise, fewer livestock farms means fewer locales with a jackpot of insect feasts.
Another culprit could be crop pesticides, which may kill flying insects, the weeds that nourish flying insects, or the birds themselves.
Or it could be climate change, which has already caused one hurricane that sent birds back north to our chilly country before the weather had changed.
The possibilities are endless.
Cadman said he hopes the forthcoming book, expected to be published in September, will be the beginning of extensive research on these birds, their habitats and their livelihood.
