Friday, January 14, 2011

Bosque Predators

The Sandhill Cranes and Snow/Ross's geese feed on specially-grown fields of maize around the refuge. Multi-species flocks comprised of Red-winged Blackbird, Yellow-headed Blackbird and Brewer's Blackbird swarm over the left-over grains, while Northern Harriers and Red-tailed Hawks sail overhead. Rows of corn are periodically flattened to allow the birds access to a steady and controlled food source throughout the winter. The more dominant cranes appear to access the freshly knocked-down cobs, where outbreaks of aggression and general social interactions are more frequent. Having access to the best feeding sites may come at a cost though. Coyotes lurk in the cover of the standing corn. Several times during my visits near the farm deck, a peaceful scene of feeding geese became a snowstorm of wings as the Snow and Ross's Geese erupted into the air in a spectacular and coordinated fashion. Up to three coyotes were trying their luck and twice I saw them get a meal by successfully grabbing a goose. There were many false alarms when the geese would half-heartedly take to the air but then quickly re-settle. On the occasions that a goose was taken, the whole flock did not return for hours. The cranes on the other hand, while still responsive to the presence of the coyotes, were far less keen to fly off. While they lack the immediate speed and agility of the geese they would flap a few feet to a safe retreat before turning and facing the Coyotes and on one occasion formed a wide semi-circle around a coyote, almost like a coordinated mob of the mammal. A few hundred long, sharp bills pointing its way was enough to make it think again and it retreated back into the corn.

The second obvious predator was the Golden Eagle, often two birds hunting together. The arrival of this species would often cause the blast-off of thousands of geese as they soared over a much wider area with the sky becoming a confusing, swirling mass of individual flocks. The power of this raptor became very clear one day when one dropped from the sky with such speed that it sent a goose thundering towards the ground as it lost is grip on the initial impact. The goose appeared to be dead after hitting the ground and the eagle came down for its meal, attended by Common and Chihuahuan Ravens and Red-tailed Hawks.

1 comment:

Nicole MacP said...

Wow, that would have been something to see... The photo with the Cranes and Coyote is a story in itself, awesome image!