Black kites: get close to HK’s most familiar raptor


A new book about HK’s wildlife shows us another side to the city

The black kite is Hong Kong’s most familiar raptor; frequently sighted soaring and screeching amongst the skyscrapers. Now, as Hong Kong eases into winter, large flocks of black kites migrate from their Northern homes to our waters. In this exclusive excerpt from ‘The Hong Kong Naturalist: A Photographic Guide to our Extraordinary Animals’ we find out more about them… 

The black kite is widespread throughout Southeast Asia and has a distribution that spreads over four continents. Probably the worlds the most common bird of prey, up to 12 subspecies have been described, though around seven are confirmed. The Hong Kong Birdwatching society has a Kite Research Group that meets every month at sunset to count kites. During the summer they limit their counts to Guilford Road, the New Yau Ma Tei Typhoon Shelter and Sai Kung.  As winter approaches Black kites numbers swell from the couple of hundred resident youths and elderly (either too young or old to make the journey) to around two thousand birds. This makes the task of counting slightly more daunting, but surveys are continued and depended on manpower sometimes expanded to other areas, like Stanley and Yau Tong. The task becomes particularly difficult around their main roosts on the forested slopes of the Peak and Stonecutter’s Island as hundreds swirl around riding the thermal waves. The best time to watch kites at these hotspots is during the evening as they return to their roosts. 

Often referred to as a black kite, the black-eared kite (milvus migrans lineatus) is the technical name for this subspecies. Despite their name, no black kite is actually coloured black; in fact they are all streaky brown, with a forked tail and finger like feathers. Typically weighing half a kilo, with an impressive metre and a half wingspan, females are slightly larger than their male counterparts. Both scavengers and opportunistic hunters, kites are not picky eaters. They feed on a diet of snakes, lizards, rodents, fish, carrion and refuse. If live prey is spotted they tuck in their wings, dive and stretch their talons to grab their meal. In Australia kites have been spotted hovering near forest fires, snatching escaping prey. One account even suggests, kites, or ‘fire hawks’ as they are known to Aborigines, pick up smouldering sticks and drop them further to spread the fire. This means they can take advantage of the subsequent exodus of frightened rodents and reptiles. Pirates of the air, kites are not afraid to steal fellow raptors meals from their grasp. However, their eyesight is not flawless, we’ve witnessed one carrying off a little boys shoe! Often hunting near the sea, feeding on dead fish and refuse, means they must have a toxin laden diet. In Japan black-eared kites  get rid of the excess mercury in their system by accumulating the poison in their feathers, then shedding them. Hong Kong kites probably use a similar process. 
Perhaps 30 pairs breed each year, although there has been no survey of nests in Hong Kong.  Kites start breeding around December and stop before the hot, sticky summer months. Acrobatic displays are performed to woo potential mates. This messy aerial courtship involves loud calling, flapping slowly,  diving, and the occasional locking of talons, tumbling down together. Some pairs may choose to nest alone, but kites are social birds and usually form large loose groups, where nests can be mere metres apart. After paring the male frequently mates with his partner. Although kites are monogamous for the season, females are happy to have fleeting affairs with other passing males. As a result, males returning from foraging trips will copulate with the female again to ensure it is his sperm that fertilizes his partners eggs. If a male is at home with his partner, he will also aggressively defend his territory against frequent trespassers. 
Both sexes help build their nest, mostly high up in the trees of Hong Kong. Kites are also known to build nests on cliff ledges, buildings or even pylons. Nests are strategically placed to avoid rainfall and wind. Built using sticks and twigs, their nests are also adorned with softer materials, like rags and plastic. A study in Spain suggests that kites decorate their nests with bright materials, particularly favouring white plastic, to signal their strength and to deter trespassers. Kites are honest, only using this signaling technique if they are in their prime (from ages 10 to 12) and strong enough to fend off attacks. 
Although both partners take part in nest building, incubation and care of chicks is primarily undertaken by the mother kite. The typical clutch size is 2 or 3 eggs; incubation lasts for approximately a month, before chicks hatch. Kites are particularly caring parents. Another study in Spain found that in comparison to red kites, black kites fed their young more and kept a closer eye on their nest. As well as this, in experimentally altered nests parents prioritized feeding smaller chicks and tried to reduce aggression between brothers and sisters. In stark contrast, siblings are not protective towards each other. Instead, they fight for food and cainism often occurs, where a younger chick commits siblicide by killing their younger brother or sister. 
Black kite’s feathers emerge quicker than other medium sized raptors and so can stand on two legs at an earlier growth stage. Baby kites start moving onto branches and flying month and a half after hatching. This is indicates to their parents they are getting ready to leave the nest, which occurs anywhere from a mere 2 weeks to another month and a half. Generally it is the offspring’s decision to fly the nest. However, if the parents need to migrate the family breaks up quicker than usual. Young kites are left behind and remain in Hong Kong for a year, before gaining enough strength to make their own journey back to Northern China.  
Kites are lucky in Hong Kong, they have plenty of other mates to play and socialize with. Evidence of play has not been officially confirmed by scientists. Nonetheless, people often recount experiences of Kites picking and dropping up sticks with each other or alone. One of the main reasons why there are plenty for these birds is they have few natural predators. The Eurasian Eagle Owl is one of these predators and does live in Hong Kong, although its numbers are scarce. The owls pluck baby kites from nests and also attack older birds. Other reasons for mortality are parasites from their diet of fish and kites predilection to perch on electric wires. In Africa they are considered an air hazard. Despite this, they are a species of least concern on the IUCN list and certainly in Hong Kong they are thriving. A permanent part of Hong Kong’s ever changing landscape, with even a beer named after them, these birds are here to stay. 
This is an excerpt from ‘The Hong Kong Naturalist: A Photographic Guide to our Extraordinary Animals’, which combines great photographs with features on animals, plus how to find, watch and photograph them in Hong Kong.
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