Stone the crows: A red list warning for rooks?

Birdlife International has released a new edition of its European Red List of Birds. A threat level is assigned to each species. Seabird wildfowl and wader numbers are falling in Europe; one in five species is now at risk of extinction.

A change in the status of one bird will raise eyebrows in Ireland. The rook, known as the ‘crow’ here, has been moved from the ‘least concern’ category to ‘vulnerable’.

There is little sign that Irish rooks are in trouble. According to Birdwatch Ireland’s latest Garden Bird Survey report, it was the 16th-commonest visitor to our gardens last winter, being recorded by 65% of survey participants, nor had there been a change in numbers since the previous winter.

But things are not so rosy for rooks elsewhere. “About half of the [European] population is experiencing decline,” the list editor notes. Numbers have fallen in France, the Netherlands, Poland, and European
Russia. Persecution and destruction of nesting sites are blamed for the decline.

‘Rook’, from the Old English ‘hroc’, is an imitation of the bird’s call. This moderately large member of the crow family has a slightly scruffy, “baggy trousers” profile and a longish black bill. Adult faces are bare. Generalist feeders and scavengers, rooks
frequent open ground in the vicinity of trees. Busy roads attract them; spilled cereal and the carcasses of birds and small mammals killed by vehicles are a food source.

Foraging only on the ground, rooks eat mainly earthworms, grain and scraps.

It was mainly to deter this species that scarecrows were invented. Gregarious by disposition, rooks like to feed in groups.

Tolerant of other species, they will associate with their corvid relative, the jackdaw, but keep a respectful distance from the grey-bodied hooded crow.

Roosting, likewise, is highly communal. Towards dusk in winter, bands of rooks are a familiar sight travelling “as the crow flies” across country to their roosts.

Thousands may gather. A roost in the Grampians had 65,000 rooks and jackdaws in 1971. Although not in the starling murmurations league, their noisy flight displays at dusk are spectacular none the less.

Nesting is also communal. Irish rookeries, high in trees, tend to have about 40 nests, but several hundred have been recorded.

Like most members of the crow family, rooks are monogamous, at least seasonally. Some pairs remain intact for life, partners even perching together in roosts.

Gregariousness has its downside. Cuckolding is widespread among colonially nesting species; a male may work tirelessly to feed an adulterer’s chicks.

Delinquency, another curse of urban living, is rife. Rooks will raid an unattended nest, plundering it for building materials.

It is not surprising that to ‘rook’ means to steal.

There’s another downside to rookeries — bullying. Farmers trapping rooks in Co Tyrone decades ago were persuaded to keep their captives in henhouses, rather than kill them, so that we could ring and release the birds later.

Dominant rooks were fat and strong when we weighed them. Others, prevented by their betters from feeding on the abundant food provided in the sheds, were on the verge of starvation. That such an intelligent, resourceful bird is in trouble anywhere is odd.

• Birdlife International, European Red List of Birds, October 2021.