 By Geoffrey Geupel |
One year ago, on October 10, 1995- within hours of containment
of the massive Mount Vision fire - PRBO biologists donned bright yellow
fire suits and hard hats and paid our first post-fire visit to the once
lush riparian valleys of Point Reyes National Seashore. In fly-overs at an altitude of 1000 feet, fire assessment team members had reported that most riparian areas in the burn appeared relatively unscathed. Our on-the-ground visits were some of the first to relay that the understory, the most important habitat for breeding songbirds, was devastated: many stretches in Muddy Hollow and Coast Camp were over 90% burned. The promise of regeneration, however, was present in the form of small patches of riparian habitat that had miraculously escaped the flames. Because the wind-fanned flames had moved extremely rapidly, burning some 9000 acres in just 24 hours on the second day of the fire, they burned different areas at different intensities. This left a mosaic on the land that included some relatively small unburned riparian patches. During the blaze, these had acted as refugia for numerous creatures, especially mobile ones like songbirds. |
In the weeks immediately after the fire, these patches were literally inundated with birds. Birds of all types persisted in them: Wrentits and White-crowned Sparrows from the coastal scrub; nuthatches and woodpeckers from the bishop pine forests; and even yellowthroats and Marsh Wrens from nearby burned marshes. Our data from bird censuses and regular mist-netting backed up our first impressions: the abundance and diversity of birds in these riparian patches in the months following the fire were higher than in nearby watersheds outside the burn area. A general consensus among ornithologists, though, was that the fire's real impact would occur this spring, when the breeding season began. During the nesting cycle, selective pressures exert a powerful force on most landbirds. For species that build open-cup nests, the average rate of nest success across North America is only 42%. When birds attempt nesting in degraded or disturbed habitats, their success drops to less than 20%: fewer than two out of ten nests attempted will fledge young, and this is too low a success rate to maintain a stable population. |
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