Woodland and Parkland Rooks: A Habitat Checklist for Birdwatchers

A rookery is one of the most generous sights in British birdwatching. The birds do the advertising for you: big stick nests bunched high in the crowns of a few tall trees, a racket of kaah-ing overhead, and a steady stream of dark shapes dropping down to feed on the fields beyond.

Because rooks nest together, and often do so close to towns, country parks and farmland, they are unusually easy to study. You need no hide, no licence and no five o'clock start. What follows is a checklist for anyone visiting woodland or parkland who wants to know whether a site is likely to hold rooks, and what is worth recording once it does.

Start with the landscape, not the birds

Rooks need two things within easy reach of each other: tall trees to nest in, and open ground to feed on. Parkland and the fringes of woodland supply exactly that combination. A rookery deep inside a dense, dark wood is unusual; a rookery in a line of mature trees along a parkland drive, with grazed pasture on one side and a playing field on the other, is entirely typical.

So the first question is not "are there rooks here?" but "would rooks choose this place?" Look for open-grown trees with broad crowns, gaps in the canopy, and short grass or bare soil within a few hundred metres. If the trees are there and the ground beneath them is grazed, mown or cultivated, you are in with a chance.

The habitat checklist

Work through this on site. The more boxes you tick, the more likely you are to find a rookery — or to explain why one has gone.

• Tall, mature trees, roughly 15–25 m, with sturdy forks and broad crowns.
• Species that hold nests well: ash, sycamore, oak, beech, Scots pine, lime, poplar and surviving elms. Rooks are not fussy, but they like big timber.
• Open-grown or edge trees — along an avenue, a field boundary, a shelter belt or the outside of a wood — rather than trees hemmed in by a closed canopy.
• Open ground close by: pasture, arable stubble, playing fields, golf courses, village greens. Short sward matters more than sheer size.
• Workable soil. Rooks probe with that pale bill, so damp loam suits them better than baked clay or deep, tussocky grass.
• Continuity. Rookeries are traditional, and many are used for decades. Old nests and the white-washed ground beneath them are evidence of history as well as current use.
• A separate winter roost, sometimes in conifers, sometimes in a town centre, often shared with jackdaws.

Reading the trees

Once you are standing under a probable rookery, look up rather than across. Rook nests are bulky affairs of sticks and twigs, lined with roots, soil and wool, and they sit high in the crown, in the outer branches where a fork gives some purchase.

How many, and where

Two or three nests in a tree is common; a large ash or sycamore can carry ten or more. Nests often cluster on one side of the tree, frequently the sheltered side, and the same trees tend to be reused year after year while neighbouring trees are ignored.

New nests and old ones

Freshly built nests look dark, tidy and solid, and the birds will still be adding to them. Last year's nests are bleached by weather, ragged at the edges and often half-collapsed. Counting old and new separately gives you a far better picture of what the colony is actually doing.

A simple calendar for rookery visits

1. Late January and February: nest building begins at many sites. Watch for birds carrying sticks and for noisy, excitable groups around the trees.
2. March and April: incubation. One bird often sits while its partner feeds nearby or returns to swap places.
3. April and May: chicks in the nest. Adults move constantly to and from the colony with food, and the noise peaks.
4. Late May onwards: young fledge. Activity at the trees falls away and flocks begin feeding further out.
5. June to August: many rookeries fall quiet, though the nests stay visible in the canopy.
6. Autumn and winter: communal roosts, often some distance from the breeding site, with large daytime flocks on stubbles and pasture.

The practical lesson: if you want to count nests, go before the leaves are out. Once a tree is in full leaf, half your birds are hidden.

What to record when you find one

• Date, time and weather, including how much leaf cover there is.
• A grid reference for the centre of the rookery, so someone else can find it.
• The number of nests, counted from at least two vantage points so you do not tally the same tree twice.
• How many trees are in use, and their species.
• Approximate nest height and position in the crown.
• Evidence of occupation: birds sitting, sticks being carried, food passes, fresh droppings below.
• Numbers of rooks present, and whether they are in the trees or feeding nearby.
• The nearest open feeding ground, and what it is — pasture, stubble, playing field.

Rook or crow? Two quick checks

Adult rooks have a bare, greyish-white patch of skin at the base of the bill; carrion crows are feathered right down to it. Rooks also look shaggier, with a peaked crown and baggy feathering around the legs, and they are almost always in company — feeding in loose flocks on the ground or moving about in noisy groups.

Juvenile rooks are the trap. Young birds have feathered faces and can look strikingly crow-like, so check for adults nearby and for the crowd rather than trusting a single bird. In flight, the steady wingbeats and the kaah call of a rook are a good deal more relaxed than the clipped caw of a crow.

Making a half-hour count count

A single visit gives you a snapshot; three visits give you a season. If you find a rookery, try to

Photo: Wolfgang_Hasselmann / Pixabay