Birds of Marlpit Community Garden July 2016
A number of species of the crow family (Corvidae) have been prominent in the Garden recently.
Flocks of rooks fly over, and carrion crows and jackdaws have been feeding in the grassy areas near the lake.
Rooks are difficult to distinguish from carrion crows, both being black birds of around the same size (about 45 cm) but if you get a good enough view you should be able to see the pale, bare skin on the front of the face of the rook. You will also see it’s ‘baggy trousers’, with the plumage looser where the legs join the body. One thing to beware of is juvenile rooks, who lack the pale skin on the face. The voice (kaaa) is slightly higher pitched and less guttural than the carrion crow (kraa) .
Rooks feed mainly on earthworms and insect larvae, but like most crows will take a wide variety of foods, including cereal grains, fruit, acorns, small mammals and birds and carrion. They can frequently be seen on motorways feasting on road kill.
One of the main characteristics of rooks is their sociability. They stick together in flocks, and breed together in tree top colonies known as rookeries. They are not always faithful partners in these communal nesting areas. Polygamy occurs, with older males mating with the females of younger males who are less able to defend them. Despite this, rooks usually pair for life, and pairs spend a lot of time together, vocalising, preening one another and even feeding one another.
Rooks are typically birds of arable farmland, and the population has increased slightly in the past few decades, indicating that it has adapted better to changing agricultural practices than other farmland birds, such as the linnet, yellowhammer, grey partridge and lapwing, whose populations have fallen dramatically. There are now about 1.1 million pairs of rooks in the UK.
Carrion crows are less sociable than rooks, though the old adage that ‘a rook on its own is a crow’ is not entirely true, since non-breeding birds will form small flocks. However, crows always nest singly, building nests out of sticks, usually in trees, but sometimes on buildings, cliff ledges or pylons.
They take a wide variety of food, not just carrion, but also insects, worms, seeds, fruit and scraps. They will also harass birds of prey and even foxes to drive them from their kills.
Crows are amongst the most intelligent of all animals and in Japan they will drop nuts in the traffic at pedestrian crossings, wait for passing cars to crack them open, then go and retrieve them when the lights turn red.
Jackdaws are the smallest member of the crow family in Britain, and like rooks are very sociable. They nest in colonies and stick together in flocks, often feeding alongside rooks on arable land. They eat grains, seeds, berries, insects and other invertebrates, and eggs and young birds.
Like rooks, jackdaws pair for life. However, unlike rooks and crows, they nest in holes, such as chimneys or holes in trees.
Their scientific name, Corvus monedula, comes from the Latin for money ‘moneta’, referring to the jackdaw’s habit of picking up shiny objects such as coins and jewellery.
Even if you can’t judge the size, they are easily distinguished from rooks and crows, even though all three are black, by the grey nape of the neck. There calls are also distinctive, a high pitched ‘jack’, which some people suggest is the origin of the name, although ‘jack’ is also an old English word for small.
The population in the UK is 1.4 million pairs. It rose in the 20th century and continues to rise.