They are variously known as suicide birds and grill birds (owing to their propensity to be smashed by vehicular grills). These are the finches of winter, and primarily they are Pine Siskins.
Pine Siskins seem to crave salt, and highway maintenance provides salt in abundance (to melt snow on the roads). So, flocks of finches settle on the highways and feed, temporarily ignoring the danger. Along comes the traffic; the finches panic and lift off. Inevitably, some of them don’t leave quickly enough and become road kill.
That any little birds are mashed by traffic is sad. However there is an interesting pattern to be seen here. The deaths do not appear to be random, but are skewed towards inept birds. In 2017, a study was made of data assembled over many years by a taxidermist. He had listed organ weight and the cause of death of 3521 birds across 251 species. An analysis showed that birds killed in traffic had relatively smaller brains. While this may seem to be natural selection at work, these deaths are hardly desirable.
In this instance, Pine Siskins have alighted beside the highway to feed on salt.
At the first sign of a threat, the birds take to the air, but some do not react quickly enough to escape being smashed by oncoming traffic.
Around where the siskins had been feeding on the highway there were many dead birds. Some were on the pavement; others had been tossed by the traffic onto adjacent snowbanks. Sigh.
A side note: I have sometimes read comments by birders who wonder why birds in a flock never collide. (Strangely, they don’t ask if birds collide, they assume an answer and ask for an explanation.) Actually, birds in a flock often seem to collide, however they recover quickly and carry on. Here, three panicky siskins are in a aerial pileup.
Hi Alistair: I’d always thought that the various species of birds on our winter highways were mainly looking for gravel or grit, spread by MOTI to help with traction. This grit is used to help grind food, such as seed and buds, in their gizzard, and when most of the world is covered in snow and ice, the highways are a ready source. I wasn’t aware that the road salt itself was the main (?) attraction. I think it was a flock of crossbills getting hit up near Apex this morning. Sad.
Kim, I used to think it was grit they were after also. But, all the authoritative birding websites say it is salt they crave. So, I asked a friend at YRB (the folks tending the highways here) what they used. It turns out that spread a mixture of gravel and salt, so that didn’t tell me anything.
If drivers are alert enough, and they should be looking far enough ahead, a quick honk of the horn will usually startle the flock in time to avoid hitting the birds.
Dave, so what conclusion can we draw from the fact that dead finches continue to pile up along the roadway?
Love these photos. We’ve had a flock over here in the Little Slocan. They don’t seem too bright at avoiding my cat, either. Also, a flock of finches, of which 4 so far have hit some windows, despite supposedly detracting decals. Interesting watching a cat eat a frozen bird she’s found the next day. She’d make mincemeat (a Christmas treat) out of that roadkill.
Vicki, usually it is ravens that carry off the finch corpses from along the road.
This is a common occurrence on the Callaghan Road to Whistler Olympic Park. Every year WOP blitzes social media asking people to watch out for Pine Siskins on the road, slow down, honk your car horn and give the Pine Siskins an opportunity to fly away.
Susi, do you suppose that the WOP’s admonition works? Or is it merely designed to satisfy an administrative directive to address the problem?