Rook Corvus frugilegus

Footprints and Tracks

Paws and feet

Rooks feet are typical of perching birds, with one long toe pointing backwards and three toes pointing forwards. The toes all have sharp claws. Adult foot size is estimated in the range of 95 to 100 mm long, although there is little information available on this. If you can help with this clue, we would be pleased to hear from you > contact.

You are most likely to find footprints where rooks have been searching for seeds or grubs on pastures with damp bare soil.

Can be confused with:

Rook footprints can be confused with the footprints of other perching bird species of similar size. Magpies are the most similar in size and most likely to forage in similar places.

Dens and nests

Rooks can form large breeding colonies of several hundred birds, called rookeries, where (in New Zealand) they live from approximately August to mid-December. They generally build their rookeries in large isolated tall trees such as pine or eucalyptus. Both the rookeries and the nests are an easily recognised sign that rooks are present. The nest is typically a large untidy platform of twigs, lined internally with smaller twigs.

Can be confused with:

Rook nests could potentially be confused with nests of some shag species since they also nest communally in large trees. However, the fishy smell of a shag colony will distinguish it from that of a rookery and shags are more likely to nest close to waterbodies and the sea. Lone rook nests could be confused with those built by magpies which make nests in a similar way.

Vegetation Damage

Understorey (less than 3m)

Rooks can pull up large clots of dirt when digging in grassland looking for grubs or seeds. Large bare patches in grassland with holes poked in to the ground may be caused by rooks (if these occur in your locality).

Can be confused with:

Other species that cause similar field damage include pūkeko pulling up seedlings; pigs furrowing; birds such as blackbirds, thrushes, magpies, seabirds and wading birds also sometime dig for invertebrates in fields. Weka can cause extensive ‘grubbing’ in pasture and kiwi also use their beaks to search for invertebrates and leave round holes. Unless sighted in the act, it is difficult to determine the particular species.

Fruits and Flowers

Rooks eat small amounts of fruit and have also been observed caching walnuts. If you find some nuts or seeds in a hole in the ground covered with grasses then you may have found a rook cache.

Can be confused with:

Rook damage to fruits and flowers can be confused with damage caused by other fruit and flower eaters, such as birds, possums and rats.

Kill Sign

Fur, feathers or scales (vertebrate)

Birds

Rooks may eat nestlings of other bird species, especially small birds and ground-nesting birds. No information could be found to describe what rook predation looks like or how it differs from other predators.

Mammal

Rooks may also eat small mammals, such as mice and may feed on already dead larger mammals. No information could be found to describe what rook predation or mammal feeding sign looks like or how it differs from other predators. Small mammals, such as mice, are probably swallowed whole, so it is unlikely that evidence is left behind. 

Lizards and frogs

Rooks can eat lizards and frogs. Not much field sign will be found because these species would be swallowed whole.

Note: some regurgitated bones may be present in rook crop castings.

Can be confused with:

Predation of other predatory and omnivorous birds, including pellets that other bird species regurgitate. Beak pecking marks on animal remains killed by larger prey or carrion could be hard to attribute to a specific bird species. Mammal predation is usually different to that caused by birds. Remember, too, that animal remains might have been scavenged.

Insects or snails (invertebrate)

The most obvious sign of rooks feeding on invertebrates is the damage they can inflict on pasture when digging for grubs. See more on this under rook damage to vegetation understorey. Little information could be found on the remnants left behind after a rook has eaten invertebrates or snails. It is possible that, like other birds, rooks peck holes in snail shells to extract the snail. Other invertebrates are likely to be swallowed whole, so no field sign will be found.

Can be confused with:

Pasture damage caused by other bird species or pigs. Sign left by other birds is likely to be similar.

Eggs

Rooks will eat the eggs of other bird species, especially of small birds and ground-nesting birds, although little is documented about characteristic signs of the egg predation. Rooks probably peck a hole in the egg.

Can be confused with:

A number of bird species prey on eggs by pecking holes in the shell and eating the contents. Mammals such as rats, stoats and possums tend to push their snouts into an egg, so the broken fragments point inwards but these often remain partially attached to the shell (or shell membrane). Remember, too, that egg remains might have been scavenged.

Other Clues

Distribution

In New Zealand, rooks are common on the east coast of the North Island from Hawke’s Bay south. They were common on Banks Peninsula but pest control has severely reduced their numbers there, and they may be completely eliminated from there.  There are reports of scattered colonies or single birds throughout New Zealand and juvenile and adult birds can disperse widely.

Sound

Rooks make a characteristic “caw’ or ‘kaah’ call, or occasionally a higher pitched ‘kiow’. These are given both in flight and while perched. Listen to audio recordings of their typical calls at New Zealand Birds Online.

Can be confused with:

Rook calls could possibly be confused with those of sulphur-crested cockatoos where their distribution overlaps (sulphur-crested cockatoos occur in New Zealand on the west coast of the North Island, Banks Peninsula and the Catlins in the South Island) but will be distinctive elsewhere.

Body covering

Rooks have glossy black feathers with a purple or green sheen.

Can be confused with:

Tūī also have glossy black feathers with a purple or green sheen.  Rook feathers will mostly be larger than tūī feathers. A black feather found on pasture could belong to a variety of bird species. Reportedly people can confuse variable oystercatcher and flying black shags for a rook.