Cool, pleasant autumn weather has enveloped the Front Range cities and early fall colors adorn the South Platte Valley. Though winter ducks have yet to arrive, resident waterfall have begun to congregate in larger, mixed flocks, abandoning their tendency to remain in family groups during the breeding season. This behavior offers several advantages throughout the colder months, including a cooperative search for food and better protection from predators.
On my visit to South Platte Park yesterday, the mixed flocks included gadwalls, American wigeon, mallards, common mergansers, blue-winged teal and pied-billed grebes. Other sightings included double-crested cormorants, Canada geese, an osprey, great blue herons, black-crowned night herons, ring-billed gulls, belted kingfishers and a lone sora, not to mention the common woodland birds.
Activity will dramatically increase in the Valley over the coming weeks as migrant and winter waterfowl move southward from the Arctic tundra and Canadian prairies. It is then that the mingling season will reach its full potential and birders will search the congregations for rare vagrants, caught up in the excitement of migrating flocks.
