(Rallus obsoletus levipes)
Construction is currently underway to replace the bridge over the San Diego River on West Mission Bay Drive, and this construction could have impacts on Light-footed Ridgway’s Rails
(Rallus obsoletus levipes) that inhabit and breed in the riparian habitat adjacent to and upstream from the bridge. The construction company building the bridge has been tasked with implementing a predator control program to offset impacts of construction to these federally- and state-endangered birds.
The Light-footed Ridgway’s Rail is a secretive marsh bird found primarily in coastal salt marshes, but can also be found in brackish and freshwater cattail or bulrush marshes in southern California. Various factors (e.g., habitat quality and small populations) are thought to limit abundance of these rails throughout their range, however, efforts such as habitat restoration and predator management have been implemented at known breeding locations to attempt to improve populations.
As Light-footed Ridgway’s Rails are reclusive and typically place their nest in dense marsh vegetation it is unlikely that avian nest predators (e.g. corvids) would be problematic during the nesting period. However, many mammalian mesopredators have been documented preying on nests of Light-footed Ridgway’s Rails, including: California ground squirrels (Otospermophilus beecheyi), rats (Rattus sp.), long-tailed weasels (Mustela frenata), gray foxes (Urocyon cinereoargenteus), striped skunks (Mephitis mephitis), Virginia opossums (Didelphis virginiana), feral cats (Felis catus), and domestic dogs (Canis familiarus). Certain avian predators (e.g. diurnal raptors, owls, and herons) have been reported to prey on Light-footed Ridgway’s Rail chicks, fledglings and adults, though the frequency at which this occurs is less well known.
In October 2018, the Institute for Wildlife Studies was contracted to conduct predator management around the bridge construction project site to reduce local predator populations and provide a higher likelihood of successful breeding attempts by Light-footed Ridgway’s Rails at this location. The predator management is slated to continue until bridge construction is complete.