before 2000, a population of feral chickens lived in the bushland. this population was boosted by local residents, who would leave chickens from their semi-rural properties on the galston side of the gorge at the bottom of the valley. steps were taken by hornsby shire council to eradicate this population, however the chickens seem to have bounced back and can often be seen wandering around the parking spaces at the base of the gorge.