BIRD SPECIES RESPONSES TO DROUGHT IN TWO SOUTHERN CALIFORNIA COASTAL SAGE SCRUB COMMUNITIES

The extended and extreme droughts that California has experienced in recent years, largely a product of climate change, have adversely affected a wide array of taxa. In the present study, we analyzed long-term data from 1983 to 2014 to assess the influence of drought on bird species in two protected coastal sage scrub habitats in southern California: the Voorhis Ecological Reserve, which lacks a supplemental water source, and the Bernard Field Station, which has a permanent source of supplemental water maintained by staff. We identified several species that exhibited significant increases or decreases in observations during drought. All species that increased in observations during drought were habitat generalists, and several species that decreased in observations during drought were habitat specialists. Most species that increased or decreased in observations during drought were also less likely to be observed at the Voorhis Ecological Reserve, while fewer were less likely to be observed at the Bernard Field Station. Several species that were observed significantly less often during drought were identified by previous studies to be likely to suffer from drought effects. Further, we identified species in our study that were observed less often during drought that are listed as California Bird Species of Special Concern: the cactus wren (Campylorhynchus brunneicapillus), loggerhead shrike (Lanius ludovicianus), northern harrier (Circus hudsonius), and coastal California gnatcatcher (Polioptila californica californica). Via the identification of drought effects across several bird species, our results add to a growing body of work that assists drought mitigation efforts.