http://animalradio.com:80/September2007.html 
Laura Dodson, Argyle Civic Association

Research shows that pigeon flocks cannot be eliminated through methods such as trapping, poisoning or other conventional means. The flock will grow back to the same size or larger as their numbers are removed. The birds mate for life in the same home and live for up to 15 years.
After months of research, investigation and meetings with City of Los Angeles officials, the Argyle Civic Association contacted PETA (People for the Ethical Treatment of Animals) for assistance with the pigeon problem. PETA, the world's largest and most important animal rights group, strongly advises against the feeding of pigeons and other wild animals.
PETA provided the resources on using advanced new methods of reducing the size of the flock. One method in particular looked promising: OvoControl™
OvoControl™ is a birth control method for birds and was registered with the United States EPA in May of 2007. The technology has been developed by Innolytics LLC, a hatch-control company based in Rancho Santa Fe, California. OvoContol™ is administered to the birds via a special "treat" which is distributed to the pigeons from rooftop dispensers. The active ingredient, nicarbazin, interferes with the development of the vitaline layer separating the egg white and yolk. This membrane is vital to the viability of the egg and without it the egg cannot develop or hatch. Originally developed to control populations of resident Canada geese, the method has also been successfully tested on feral pigeons under the guidance of the USDA Experiment Station in Gainesville, FL. http://argylecivic.org    Hear Laura Dodson Animal Radio®