If Australians think the coronavirus lockdown has been tough, spare a thought for the crows.
That is the view of one reader who says that a lack of roadkill – caused by reduced traffic on local roads at the height of the pandemic – had resulted in the crows going hungry.
The reader phoned to give an account of a vast flock of crows descending on his property at Ouse to fight over the carcass of a single rabbit. He said the flock numbered at least 100 birds.
“They were fighting, squabbling over the tiny carcass,” the farmer said. “I went to investigate and, yes, it was merely a rabbit, which by now had been picked to bits. There was only a pile of fur left.”
The reader said that earlier that day he had taken a drive on the Lyell Highway running through the village and had noticed the lack of roadkill. In turn, there had been a lack of crows, which are usually commonly seen on all Tasmanian roads, feeding on roadkill.
By coincidence, the account of hungry crows – or forest ravens, to give them their proper name – came shortly after I had read a scientific study of the impact of roads and road-building on wildlife.
The study was not so much about roadkill but about the actual roads themselves, and how they were altering the biological landscape. Was traffic noise, for instance, drowning out the mating and territorial calls of birds, and therefore affecting breeding success.
A team of British and American researchers and experts from two British ornithological organisations say many highway developments have had an adverse, sometimes devastating, impact on wildlife but most studies have been on a small scale. And the scientists say it can only get worse. The global road network spans more than 45 million lane-kilometres in length and this is expected to reach 70 million lane-kilometres by 2050. At the same time, the number of vehicles is expected to double.
As a basis for their research, published in the Journal of Applied Ecology, the scientists studied 51 of the most common and widespread breeding bird species in Britain to establish how roads might affect them. They looked at areas where bird counts had been conducted, comparing traffic volume on roads within a five-kilometre radius. Other factors known to affect bird populations were taken into account, including agricultural intensity, human population, habitat and climate.
Although the scientists conceded their study had limitations, it was found that roads certainly had an impact on bird populations, on a scale comparable to that of agricultural activities.
Their work highlighted the need for mitigation of roads, particularly in areas important for avian biodiversity. This could include efforts to reduce impacts of road noise and collisions, such as reduced speed limits or quieter road surfaces in sensitive areas.
Reading the list of birds impacted by roads, it was interesting to see one avian family thriving in the habitat of the highway when traffic is flowing – the corvids, or crows.