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2010 Map of Nuttall's Lotus in Oceanside & Carlsbad, Encinitas, Mission Bay, and Imperial Beach.

Surveys for the endangered least Bell's vireo (Vireo bellii pusillus) were conducted at the San Luis Rey River Flood Control Project area in the city of Oceanside, San Diego County, California, between 1 April and 15 July 2007. Three protocol surveys were conducted during the breeding season and supplemented by weekly territory monitoring visits. One hundred and eight least Bell's vireo territorial males were identified; all but three males were paired. The vireo population in the project area declined by 9% (11 territories) from 2006, the largest drop observed in five years. Overall there was a net increase of five territories in the channel where exotic and native vegetation removal has occurred (Treated) and a net loss of 16 territories in the Untreated sites where vegetation removal will not occur (Untreated), suggesting that factors other than vegetation removal may have contributed to the 2007 decline. Factors contributing to the vireo decline may include drier conditions, reduced habitat quality, and human disturbance. The majority of vireo territories (70%) occurred in habitat characterized as Willow Riparian. Ten percent of birds occupied habitat co-dominated by willows (Salix spp.) and cottonwoods (Populus fremontii), and 20% of territories were found in Riparian Scrub, dominated by mule fat (Baccharis salicifolia) and/or sandbar willow (S. exigua). Most vireo territories (63%) were established in habitat where 50 to 95% of the vegetation cover was native species while 37% of the territories were in habitat vegetated almost entirely (>95%) by native species. Giant reed (Arundo donax) was the most common exotic species within territories followed by black mustard (Brassica nigra), poison hemlock (Conium maculatum) and tamarisk (Tamarix ramosissima). Nesting activity was monitored in 97 territories. Pair success from both treatments was comparable; 82% (50/61) of Treated pairs vs. 87% (27/31) of Untreated pairs were successful in fledging young from at least one nest. Nest success (number of nests fledging at least one young/total number of nests found) of pairs breeding in the channel (Treated) did not differ statistically from that of pairs breeding in the Untreated sites (49%; 60/122 vs. 59%; 32/54). Successful and failed nests within Treated and Untreated sites did not differ statistically in average nest height, height of the host plant, or the distance the nest was placed from the edge of the host plant. Eighty to ninet

Surveys for the endangered least Bell's vireo (Vireo bellii pusillus) were conducted at the San Luis Rey Flood Control Project Area (Project Area) in the city of Oceanside, San Diego County, California, between 1 April and 15 July 2008. Three protocol surveys were conducted during the breeding season and supplemented by weekly territory monitoring visits. A total of 130 least Bell's vireo territorial males were identified; 117 were confirmed as paired, four were confirmed as single males, and nine were not confirmed as paired. Six transient vireos were detected during surveys. The least Bell's vireo population at the San Luis Rey Flood Risk Management Project Area increased by 20% (22 territories) from 2007, to achieve the highest number of territories ever detected at this site. We evaluated the impact of ongoing channel vegetation clearing and giant reed (Arundo donax) eradication that has occurred in the river channel since 2005 on the Project Area vireo population by comparing vireos in the river channel (Channel), where vegetation treatment has occurred, with sites outside of the river channel (Untreated), where vegetation treatment has not occurred. While the total number of territories in 2008 at Untreated sites outside of the river channel rebounded to the same number as in 2006, the number of territories in the Channel, increased by 11 territories since 2006. Therefore, despite major habitat changes between 2005 and 2008 within the Channel, vegetation removal did not appear to have a negative impact on the abundance of vireos in 2008. The majority of vireo territories (64%) occurred in habitat characterized as willow riparian. Sixteen percent of birds occupied habitat co-dominated by willows (Salix spp.) and cottonwoods (Populus fremontii), and 20% of territories were found in riparian scrub, dominated by mule fat (Baccharis salicifolia) and/or sandbar willow (S. exigua). Most vireo territories (61%) were established in habitat where 50 to 95% of the vegetation cover was native species, 38% of the territories were in habitat vegetated almost entirely (>95%) by native species, and one territory was placed in habitat where 5 to 50% of the vegetation cover was native. The most common exotic species within territories was A. donax followed by black mustard (Brassica nigra), poison hemlock (Conium maculatum) and tamarisk (Tamarix ramosissima). Nesting activity was monitored in 102 territories. Pair success was slightly higher fo