Neighbourhood Bully in a Size of a Crow

The House Crow (Corvus splendens) has been reportedly seen attacking Singaporeans and even other animals. Some people suffered from scratches on their faces or head when the crows dive at them. In the most recent case, STOMPer Ong witnessed a series of crow attacks on passerby along Choa Chu Kang Street 1 on 1st April 2010 . ( see video at http://tinyurl.com/whats-going-on-crows-attack) House crows were caught harassing other birds too. Allan Teo and Tang Hung Bun observed a House crow harassing Black-Shouldered Kites (Elanus caeruleus) and White-Bellied Sea Eagles (Haliaeetus leucogaster).  Other small animals may also be attacked by these aggressive House Crows. Gloria Seow witnessed a Common Fruit Bat (Cynopterus brachyotis) being attacked by about six House Crows.
 
A Common Fruit Bat attacked by six House Crows http://besgroup.blogspot.com/2006/04/house-crow-and-bat.html

A Common Fruit Bat attacked by six House Crows http://besgroup.blogspot.com/2006/04/house-crow-and-bat.html

 
 
A House Crow harassing three juvenile Black-Shouldered Kites http://besgroup.blogspot.com/2007/01/harassment-of-black-shouldered-kites.html

A House Crow harassing three juvenile Black-Shouldered Kites http://besgroup.blogspot.com/2007/01/harassment-of-black-shouldered-kites.html

According to most studies, this display of aggressiveness from the House Crows is usually associated to food or nest-defense. However, being in an urban habitat with a dense human population, the House Crow should have be habituated with humans already. So what makes them aggressive and thus publicly labeled as pests or bullies?
 
Bird study in J.D Lockie regarding aggressive behaviour of crows indicated that crows may fight with each other over food. It is stated that during winter there is usually an increase in crow fights because of shortage of food. However, in Singapore where food is abundant and climate is always hot and humid, it does not really account for the House Crows’ aggressive behaviour.
It is most likely due to nest-defense.  A research comparing between rural and urban crows by Department Wildlife Ecology, University of Wisconsin shows that urban crows do display higher aggressiveness when threatened as rural crows are more afraid of humans. So crows may attack Singaporeans out of defense because their nests are nearby.
However, in the same research, it also show that urban crows have higher tolerance to humans than rural crows. Urban crows will not feel threaten easily when humans are near their nests.
This contradicts the reason behind crow attacks. One theory could be that the House Crows are becoming more daring as they become less afraid of humans. Thus, they might pester human for food instead. 
 
 Reference cited:
“What’s going on? Crows attack passerby at Choa Chu Kang” by STOMPer Ong. STOMP-Singapore Seen, 1st April 2010.
” Harassment of Black- shouldered Kites” by A. Teo and Tang H.B. Bird Ecology Study Group, Nature Society (Singapore). 6th January 2007.
“The House Crow and the Bat” by G. Seow. Bird Ecology Study Group, Nature Society (Singapore). 20 APril 2006
 

 

Lockie, J. D.(1956) ‘Winter Fighting in Feeding Flocks of Rooks, Jackdaws and Carrion Crows’, Bird

 
 

 

 

Study, 3: 3, 180 — 19o

 

 

 

Knight, R.L. (1987). Nest Defense Behavior of the American Crow in the Urban and Rural Areas. The Condor. 89: 175-177