Oct 112019
 

Grassland birds and aerial insectivores among the hardest hit

When I was a teenager in the 1960s, the Peterborough Field Naturalists made an annual June visit to Harry William’s farm near Millbrook. This was not your average nature outing. You were expected to arrive no later than 4:00 am. Why, you may ask? To take in the dawn chorus as the world would reawaken to a cacophony of bird song. Upon arriving, the most dominate  voices were those of the whip-poor-wills. They were deafening. In fact, as former club president, Martin Parker, recalls, “It was so loud your head throbbed.” Once the whip-poor-wills quieted down, other species began to sing. They were always right on cue, each at its own designated time. First came the thrushes, followed in order by the sparrows, the buntings, the warblers, and then field birds like meadowlarks. You were buffeted by a continual wave of sound. The challenge was trying to pick out and identify the different voices competing for airtime.

Fast forward to 2019. When you walk outside at dawn, even in wilderness areas, the relative silence is eerie. Yes, birds are still singing, but the boisterous wall of sound is gone. Parker agrees. “I find the dawn chorus at my cottage getting quieter and quieter every year.”

An alarming report

According to a study published this September in Science magazine, North America has lost nearly three billion birds over the last five decades. Take a moment to let that number sink in. Stated another way, about one-third of the total bird population we had in 1970 has disappeared. The study looked at 50 years of data gathered by volunteers who carry out annual bird censuses like the Breeding Bird Survey, provincial and state breeding bird atlases, and the Christmas Bird Count. Scientists also looked at data from 143 weather radars, which pick up the millions of birds migrating in the spring and fall through the sky. The decline was there before their very eyes. Although the drop in bird populations has been known for a long time,  the authors of the study were stunned by the scale of the loss.

This is not so much a story of extinction – although that may soon be the reality for some species – but rather the story of a “great thinning”, in which once-abundant birds have declined to a fraction of their former numbers. It should serve as a stark warning. As Ken Rosenburg, the study’s lead author said, “Birds are so interwoven with everything else (in nature) that if we’re seeing this loss and degradation in birds, we can be pretty sure it’s happening with other groups, and that it’s a symptom of a much larger problem with the environment that will ultimately affect people.”

A good case in point is the world-wide decline in insects. We need look no further than the windshields of our cars. No longer are they splattered with dead moths, butterflies and other insects like they once were. Insects, of course, sustain birds.

 The worst declines

Three bird groups in particular have taken the brunt of the downturn. Canada has lost 40 percent of its shorebirds and nearly 60 percent of its grassland and aerial insectivore populations. These groups also make up 80 percent of all bird species that have been newly assessed as threatened or endangered in Canada.

Let’s look at grassland species. These include familiar birds such as killdeers, meadowlarks and bobolinks. A grassland can be a prairie, a field that is no longer being farmed, or even a hayfield. Bobolinks, which love to nest in hayfields, have plummeted by 88 percent. One reason is that hayfields are often mowed during the breeding season, which destroys the nests. Grassland birds are also threatened by changing agricultural practices such as intensification, removal of hedgerows, and inputs of pesticides.

Along with the Renfrew area, the Kawarthas has the highest nesting densities of bobolinks in Ontario. I asked Dr. Erica Nol, professor of biology at Trent University, what could be done to help this species recover. She said, “Working with farmers to set aside hayfield reserves on their farms would be a useful strategy. The fields don’t have to be large and, of course, the farmers would need to be compensated. Many grassland species wouldn’t be here if it wasn’t for farmers.”

Aerial insectivores – birds that feed on the wing by catching flying insects – have declined by 59 percent across Canada. This group includes swallows, martins, whip-poor-wills, nighthawks, chimney swifts, and flycatchers. The precipitous drop in barn swallow numbers has been most noticeable. Any farmer over the age of 50 can attest to the large flocks of swallows that once nested in barns and lined telephone wires. Cottagers of a certain age will remember how common they were in boathouses.

We are already well aware of the negative impacts of neonicotinoid pesticides on bee populations, but now the link between these pesticides and bird health is becoming clearer.  A recent study done by Dr. Marc Bélisle of the University of Sherbrooke  found that barn swallows fare less well in areas of intensive agriculture where pesticides such as neonicotinoids are applied. Not only do the young have a harder time surviving, but adult birds suffer from lower body weight.

As for shorebirds like plovers and sandpipers, long-distance migrants have declined most steeply. Many of these nest in the Arctic and overwinter in Central and South America. Shorebirds depend on coastal areas and inland wetlands for breeding, migration, and wintering. Vital shorebird habitat is being lost to coastal development and suffers from human disturbance such as dogs running free on the beach. Key to their conservation is protecting migration stopover and wintering sites.

When it comes to forest-dwelling birds, the picture is more nuanced. Although more forest birds have increased (e.g., blue-headed vireo, pileated woodpecker) than decreased in the past 20 years, there are still many woodland species that are declining. The drop in warblers – often the most popular species with birders – is especially sad. As a group, they are down by 600 million. The cerulean warbler has been especially hard hit.

If you were to point to one reason for bird decline, it is loss of habitat. This is a problem not only on breeding grounds, but also during migration and where the birds spend the winter,  often in Latin America. This highlights the need for strong international conservation action.

The impact of climate change is also an increasing concern. The new superstorms, fueled by our warming oceans, can have a huge impact on birds and insects. Wildlife in Puerto Rico was devasted by hurricane Maria – even the bees. There is also a growing fear that long-distance migrants, which are declining faster than resident species, will not be able to adjust their migration schedules to coincide with the shifting peak abundance of their far away food sources. This effect is known as “decoupling” and is already a cause of seabird decline. Rising sea levels will also reduce available habitat for coastal nesting birds.

It’s not all bad news, however. Some bird groups are actually faring better. Since 1970, geese and duck populations have more than doubled, as have birds of prey like hawks and falcons. Big birds in general seem to be faring well, too, with 11 of Ontario’s 12 heaviest birds showing a marked increase in the past 20 years. Among these are the sandhill crane and the wild turkey.

Waterfowl in particular have benefited from investments in habitat conservation by government, non-government and industry organizations. Raptors have rebounded from their precarious population levels of 50 years ago thanks to the ban on the indiscriminate use of DDT.  When we understand the problem and act together, conservation works.

What to do?

As with climate change, individual action is important, but new laws and the investment of public money are key. Conservation charities can’t do it alone. Anyone voting with conservation in mind can’t help but be impressed with the Liberals commitment to protect 25 percent of Canada’s ocean waters and land by 2025 and to plant two billion trees by 2030. Both of these policies will greatly benefit birds and other wildlife. I fear, however, that a Conservative government would make deep cuts in the conservation and habitat protection budget in their rush to lower the deficit. Money for protected areas and endangered species is always seen as low hanging fruit for cost savings by fiscal conservatives.

Individuals can be part of the solution, too, by donating to conservation groups like Bird Studies Canada, buying bird-friendly shade-grown coffee, keeping cats indoors, planting shrubs and wildflowers in your yard, and making windows bird-safe (see Bird Friendly Homes at allaboutbirds.org). The most effective product to apply on windows is “Feather Friendly” dotted tape, which is sold at the Avant-Garden Shop in Peterborough.

The success in bringing back waterfowl and raptor populations is proof that conservation and legislation can work. I dream of the day when our fields and forests will once again reverberate with the variety and intensity of bird song that I knew as a teenager all those years ago on the William’s farm.

What to watch for this week 

We are fortunate that the peak colour of most red and sugar maples will coincide this year with Thanksgiving Weekend. Be sure to get out and enjoy the show. Two near-by areas with a great colour display are Gooderham, north of Buckhorn, and Chandos Lake, east of Apsley.