Non-native species are rarely beneficial and introducing them or allowing them to become established is often detrimental to ecosystems that have built up over tens of thousand of years (just think of the havoc that rats and mice are having on bird populations on small islands) and one species that is currently jumping ship in ports across the world is the House Crow, which has been given the scientific name of Corvus splendens: the ‘Glossy Crow’. For those of you thinking that having a ‘Glossy Crow’ in their neighbourhood might not be such a bad thing, read on…
One of the first “ticks” that birders from Europe and the US will get on a trip to the Indian sub-continent is the House Crow Corvus splendens. Bold, noisy, abundant and almost totally unafraid of people House Crows fill a similar ecological niche to the more northerly Carrion Crow Corvus corone, but have spread out from rural habitats and are now found in every city, often scrabbling in large flocks through piles of garbage at the sides of roads.
Chennai, southern India
In many parts of India House Crows are regarded as beneficial because of their scavenging habits – but in other parts of the world they’re not so welcome. Considered by some to be overly aggressive and detrimental to indigenous bird populations, this intelligent bird is expanding its range considerably. For example, ships passing through the Suez Canal, “possibly warships returning from the Gulf War“, provided an opportunity for the House Crow to reach Europe. The first European record was from Gibraltar in March 1991, and a small breeding colony has since become established in Holland.
Introduced or self-introduced House Crows are now common in Israel, South Africa, Malaysia, Singapore…the list goes on and on. Whilst the following excerpts are by no means intended to be an exhaustive survey, they perhaps give some indication of why the addition of House Crow to the national bird list might not always be seen as a cause for rejoicing…
www.gisp.org/casestudies/S E Asia:
As an avian invader, the Indian House Crow is undesirable for a host of reasons. It is an aggressive and opportunistic feeder, and has a devastating impact on indigenous bird populations by eating eggs and chicks, and mobbing other birds that might compete with it. It threatens the local wildlife by preying heavily on frogs, lizards, small mammals, fish, crabs and insects. The crow was introduced to Malaysia as a biocontrol agent of rhino beetles in oil palm estates.It affects agricultural productivity by stripping fruit trees in orchards and decimating grain crops, eating chicks of domestic poultry, and has even been known to peck out the eyes of sheep and pigs. It is unafraid of humans, and may enter houses to steal food, dive-bomb people walking past the nest, and frighten children by snatching food from their hands. House Crows have also been blamed for causing power cuts in some areas, as they often construct nests out of wire in electric pylons.
The House Crow is not an indigenous bird of Singapore. Its natural distribution extends from South Asia which covers Pakistan, India and Sri Lanka to southern China and some parts of Indochina that include southern-western Thailand (Madge & Bum, 1994). This crow has become widespread by introduction or self-introduction to many countries around the Indian Ocean and other parts of the world. In the 1920s, an attempt to introduce the House Crow in Singapore was unsuccessful (Bucknill & Chasen, 1927). The present established population in Singapore probably originated from introduced birds that were probably transported by ships from India and Sri Lanka in 1940s (Hails & Jarvis, 1987; Madge & Bum, 1994).
National Geographic, January 2007:
“Ripping apart garbage bags, rummaging through leftovers, scavenging at food stands, crows have earned the enmity of sanitation- obsessed Singaporeans. The tiny Asian island nation is infamous for its strict rules to promote cleanliness, including a ban on most chewing gum in public places.
And when it comes to crows, neatness isn’t the only concern, as dive-bombings have been known to leave Singaporeans smarting…”
Corvus splendens, the Indian House Crow, is an exotic bird, which is rapidly becoming semi-localised in cities along the east coast of Africa. It has become a major problem in countries such as Mozambique, Kenya, Tanzania, Malaysia and Mauritius. The first ever report of its presence in South Africa was in 1972, when a flock of 60 birds was situated at Sodwana Bay. It’s emergence in Durban has come at a time when most Durbanites are aware of the problems created by the Indian Myna infestations. Although there are relatively large numbers of house crows in the Metro area (and further afield), it is still possible to control their numbers effectively, although at this stage total eradication would be preferred.
The Indian House Crow (Corvus splendens) first appeared in Eilat in 1976 (Paz, 1987) where about 300 individuals are living presently, and is occasionally seen north of Eilat along the Arava Valley.
For more information visit Colin Ryall’s extensive House Crow Monitor.
Additionally, there is a fascinating post on James Wolstencroft’s wonderful blog, Birdman, consisting of email exchanges about the population of House Crows on the Tanzanian coast (where the birds were introduced by British civil servants who apparently hoped they would help keep the streets clean).
UPDATE on MEBirdNet by Keith Betton: July 2009 – ‘Alien invasive House Crow Corvus splendens has been successfully removed from the island of Socotra. “Eradication of the House Crow from Socotra has removed the risk posed to our native fauna”, said Nadim Taleb – the National coordinator for the GEF, Governance and Biodiversity Mainstreaming Project. This news follows ten years work by the Environment Protection Authority (EPA) and Socotra Archipelago Conservation and Development Programme (SCDP). House Crow arrived on Socotra in 1996 and built up a breeding population of over 10 pairs which posed a threat to native biodiversity. Numerous attempts to trap them failed but an imaginative scheme to control their numbers was successful. Children were paid a reward for bringing a nest containing young to the Socotra Archipelago Conservation and Development Programme. The last birds were killed by a marksman this spring. “The Invasive Species Control Group freed Socotra from the invasive House Crow”, said Omar Al Saghier, National Coordinator for GEF-Small Grant programme. “We now wish them success in their efforts to work alongside local communities to eradicate invasive plants”. The work was undertaken by the Invasive Species Control Group, the EPA and SADP using GEF-Small Grant programme funds.” ‘
For a really good example of a leucistic House Crow and an amusing discussion have a look at Daisy O’Neill’s post on the excellent Bird Ecology Study Group (BESG) website (and my thanks to Daisy for allowing me to reproduce one of her photos below, and to YC Wee for acting as go-between!). The BESG site also has some interesting observations on House Crow behaviour at http://besgroup.talfrynature.com/category/crows/.
Leucistic House Crow, Penang, Malasia. Copyright Daisy O’Neill
All photographs on this page © Charlie Moores, except image above © Daisy O’Neill