Saturday, July 11

We all come home to roost


Rooks roost high on trees. – Photo by Florence Chew

WHETHER, after a hard day’s work, earning our keep, we travel back to our homes by car, bus, or motorbike, we breathe a sigh of relief to return to our nests. Our homes, like bird-nests, provide us with a sense of security. Birds, like us, often travel in swarms during rush hours at the end of the day after many hours hunting for sustenance. They feel safety in flying in large conglomerations to reach their nests. This, I have observed amongst rooks and starlings in the UK and hornbills and swiftlets in Sabah and Sarawak.

A clamour of rooks

Rooks (Corvus frugilegus) are really large crows but with a black violet sheen plumage. They feed on insects, worms, and grain. The most gregarious of all European crows, they build their nests on tall trees and live as a commune in rookeries. Their large, untidy nests are made of dried twigs and lined with mosses and feathers. Pairs of birds renovate the same nests season after season and some nests are considered to be several centuries old!

The rookery opposite my house, in a small wood, houses about 500 pairs of birds. Larger rookeries may hold several thousand pairs. Local farmers believe that when rooks desert their rookery this presages a food shortage.

The expression ‘as the crow flies’ specifically applies to the direct straight line flight of these birds. Even the nautical term ‘the crow’s nest’, which is a masthead, lookout barrel on an early 19th century sailing ship, depicts the height of the rook’s nest in surveying the world around it.

These birds have long had a special reputation for foretelling the weather: if tumbling through the air or flying very low, rain is predicted but, if seen flying high, then fine weather is almost guaranteed. Their distinctive cries of ‘kah’ alert me at dusk to see my feathered friends coming home to roost in large numbers to their high tree nests.

A murmuration of starlings

Whilst, recently driving, at dusk, with a Malaysian friend across the Somerset levels – an area of lowland prone to hectares of floodwater in winter – we saw thousands of starlings wheeling around the skies. Their flight patterns were three dimensional as they swirled in corkscrew-fashion. Such a spectacle is known as a murmuration of starlings.

The starling (Sturnus vulgaris) has glossy blue-black plumage with a purple and green sheen and a yellow beak. Its favourite food is the leather jacket – the larva of the cranefly. These birds are often seen amongst cattle and feed on the insects disturbed by the grazing animals. They also perch on the backs of sheep, picking the ticks off.

In Somerset, the local word for this bird is ‘sheep stare’. It is reckoned that, with increasing intensive cultivation dependent upon chemical pesticides, the total population of starlings is rapidly diminishing.

Certainly gregarious by nature, they are sometimes seen in really vast flocks, settling on buildings or trees to roost. They have become more urbanised and omnivorous in their eating habits and, like pigeons, their excretion over stone work has led to the deterioration of the facades of buildings. Expert mimics, some ornithologists, in cities, have heard these birds mimic car-alarms.

Swiftlets in a nest in Mulu National Park. – Photo by Bernard Dupont

A flight of swiftlets

Twenty years ago, I was leaving Niah caves at twilight when I witnessed thousands of swiftlets returning to their nests on the cave walls and at the same time there was an exodus of thousands of bats into the darkening sky. It was like a commuter’s rush hour and surprisingly there were no collisions unlike thousands of travellers moving in opposite directions at London’s or Tokyo’s underground stations. Both the cave bats and cave swiftlets; the latter of the species, Aerodramus, are insectivores and also possess echolocation in making their ways back to their respective roosts and nests in caves.

Swiftlets are not confined to Southeast Asia but are exclusively found in subtropical and tropical regions. With very short legs with only four claws on each, they easily cling on to near vertical surfaces at the top of cave walls. It was only at the Bau caves that I have ever looked into a nest to see a clutch of two small eggs. In my visit to Niah caves that I saw, out of season illegal guano collectors bagging swiftlet and bat droppings, and nimble climbers on precarious bamboo, makeshift scaffolding collecting swiftlets’ nests by candlelight. I shut my eyes in fear. Such caves are not the ideal places for the fainthearted or those with sensitive stomachs. Whatever the intrinsic nutritional value of bird-nest soup, I have only sampled it once and then many moons ago. Such nests are made by the monogamous swiftlets’ saliva in binding together bits of twig, grass and feathers. I was totally amazed by these birds’ agile, aerodynamic acrobatics.

A ‘host’ of hornbills

Unfortunately, I cannot find a collective noun for a group of hornbills in flight so I have suggested a ‘host’. My first memories of viewing hornbills in flight was along the banks of the Kinabatangan River in Eastern Sabah. By day a host took off from their nesting places, in search of ripe fig fruit, before returning to their roosts, undoubtedly well fed, at dusk It was on a boat ride there that I became interested in hornbills and it was no surprise to me that, later in life in visiting Sarawak, I discovered that the Rhinoceros hornbill (Buceros rhinoceros) is the official state animal of Sarawak.

A Rhinoceros Hornbill nips at a peanut. – Photo by Thomas Quine

Unlike other birds, their first and second neck vertebrae are fused, in order for them to support their heavy bills. To see a hornbill feeding is quite spectacular for whilst using the tip of its bill to pick at fruit, its tongue is too short to shovel its food down its craw to swallow. So, this bird throws the fruit back into its throat through a series of distinctive head jerks. It’s almost like humans gargling with mouthwash!

It was the former early 20th century curator of Sarawak Museum, Robert Shelford, in his book of 1916 entitled, ‘A Naturalist in Borneo’ that best reminded me of my first sighting of a host of hornbills. He wrote, “I heard a peculiar rushing noise made by hornbills as they fly … and from various directions, I could see numbers of these birds winging their way to a huge Ficus (fig) tree that was close in fruit to (my) camp.” This, he witnessed on an expedition to Penrissen.

Each and every species whether bird, animal, or human quietly or loudly vocalise on returning to their nests and homes to feed their families and then relax before repeating the same ritual day in day out. Alas, may I assure younger readers that the thought of retirement from work is no better for there are daily targets to seek, reach, and meet.