|Scientific Name:||Pica nuttalli|
|Species Authority:||(Audubon, 1837)|
|Red List Category & Criteria:||Near Threatened ver 3.1|
|Facilitator/Compiler(s):||Butchart, S., Derhé, M., Ekstrom, J., Sharpe, C J, Symes, A. & Taylor, J.|
This species has been uplisted to Near Threatened on the basis that it has undergone a moderately rapid population reduction owing to mortality caused by West Nile Virus, which caused a crash in its population from which it now appears to be recovering.
|Previously published Red List assessments:||
|Range Description:||Pica nuttalli is endemic to California, USA, occurring west of the Sierra Nevada mountains (del Hoyo et al. 2009). The species's population, estimated at c.180,000 individuals in 2003, is thought to have been reduced by 49% by 2006 (del Hoyo et al. 2009), owing to the impacts of West Nile Virus. Following a low in 2007-2008, the population now appears to be recovering (W. Koenig in litt. 2012).|
|Continuing decline in area of occupancy (AOO):||Unknown|
|Extreme fluctuations in area of occupancy (AOO):||No|
|Estimated extent of occurrence (EOO) - km2:||83500|
|Continuing decline in extent of occurrence (EOO):||Unknown|
|Extreme fluctuations in extent of occurrence (EOO):||No|
|Continuing decline in number of locations:||Unknown|
|Extreme fluctuations in the number of locations:||No|
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||The species's population was estimated at c.180,000 individuals in 2003, but is thought to have been reduced by 49% by 2006 (del Hoyo et al. 2009) owing to West Nile Virus. The population now appears to be in recovery (W. Koenig in litt. 2012), thus the population is placed in the band for 50,000-99,999 mature individuals, which is assumed to equate to c.75,000-150,000 individuals in total.
Trend Justification: Over the last 40 years of the 20th century, Breeding Bird Survey (BBS) and/or Christmas Bird Count (CBC) data indicate that the population of this species was stable (Butcher and Niven 2007), although an analysis of CBC data by Airola et al. (2007) suggests that the species had been increasing on average between 1980/1981 and 2001/2002, while an analysis of CBC data from Califronia’s Central Valley indicates a steady decline of c.10% annually on average between 1995 and 2006. However, the species suffered high levels of mortality and a severe population decline owing to West Nile virus, to which it is highly susceptible (Airola et al. 2007, Crosbie et al. 2008). Following the documented arrival of the virus in California in summer 2003 (Reisen et al. 2004), data have suggesting a decline of 42-49% from 2004 to 2006 (Crosbie et al. 2008). Christmas Bird Count (CBC) data from the Lower Sacramento Valley suggest that numbers of this species declined by 48% between 2004/2005 and 2005/2006, with surveyed numbers in 2005/2006 having declined by 38% compared to the previous 10-year average when accounting for the effects of bad weather (Airola et al. 2007). The population appeared to reach a low in 2007-2008, and since then has shown signs of recovery, although it was still depleted in 2010/2011 compared to data collected since the late 1950s (W. Koenig in litt. 2012). Given that the population appears to have crashed in 2003-2008, and has shown some signs of recovery, it is suspected that the species has undergone a moderately rapid population reduction (25-29%) over the past three generations (21 years).
|Current Population Trend:||Increasing|
|Habitat and Ecology:||This species inhabits oak savanna with large trees scattered among broad expanses of open grassland and pasture (del Hoyo et al. 2009). Over recent decades, it had been increasing in suburban settings, notably in the Sacramento Valley. It forages in cultivated fields and orchards. This omnivorous species feeds on a range of items, including invertebrates, small mammals, bird eggs and nestlings, carrion, food discarded by humans, grains, fruits, nuts and other seeds. Nest-building takes place from December through to March, with egg-laying from March to May (del Hoyo et al. 2009).|
|Continuing decline in area, extent and/or quality of habitat:||Unknown|
|Generation Length (years):||7.1|
|Movement patterns:||Not a Migrant|
|Major Threat(s):||The predominant threat to the species is mortality caused by West Nile Virus, which was first documented in California in 2003 (Reisen et al. 2004). This virus caused a crash in the population until 2007-2008, after which some recovery is evident (W. Koenig in litt. 2012). Prior to 2004, the species was locally abundant in some areas, but declining in others owing to urban development on oak savanna, for example in Salinas Valley and areas south of San Francisco (del Hoyo et al. 2009). Habitat is also being lost to agricultural expansion. In addition, the species is susceptible to poisons used for killing ground squirrels (Sciuridae), and is threatened by summer droughts (which reduce the abundance of large insects), as well as the impacts of Sudden Oak Death (del Hoyo et al. 2009).|
Conservation Actions Underway
This species has been the subject of monitoring through citizen science surveys.
Conservation Actions Proposed
Continue to monitor the species's population trend through regular surveys. Protect areas of suitable habitat.
|Citation:||BirdLife International. 2014. Pica nuttalli. The IUCN Red List of Threatened Species 2014: e.T22705874A61893932. . Downloaded on 29 November 2015.|
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