Presentation Title

Preferences of Cavity Nesting Bees in Portland

Abstract

Little is known about the diverse life histories of our many native bee species, although many are threatened by habitat loss through urbanization. For example, few studies have examined the role of nest height or cavity size in attracting our lesser known native cavity-nesting bees. To remedy this paucity of data, we set up cavity nest boxes across fourteen locations in the greater Portland area and erected wooden posts with nest blocks at 3 different heights (0.5, 1.5, and 2.3 meters). To accommodate a diversity of bee species, cavity diameters ranged in size from 3.0 to 10.0 mm. From these nests, we collected data to determine nest occupancy, nest diameter size preferences, and percent bee and wasp occurrence rates. The overall nest height occupancy rates greatly varied amongst the fourteen locations, but overall the 2.3 m height had the greatest percent occupancy. Although the bees and wasps from the nests collected in 2019 have not yet emerged we estimate that the nests will yield about 68% bees and 32% wasps. Lastly, the greatest occupancy rates were observed in the two smallest cavity diameters, 3.0 and 4.5 mm. Nesting preference data will be used to better inform residents of greater Portland how best to provide nesting habitat for cavity nesting bees, and the solitary wasps that use similar nesting sites.

Subjects

Habitat assessment, Animal ecology, Wildlife biology

Persistent Identifier

https://archives.pdx.edu/ds/psu/33816

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Preferences of Cavity Nesting Bees in Portland

Little is known about the diverse life histories of our many native bee species, although many are threatened by habitat loss through urbanization. For example, few studies have examined the role of nest height or cavity size in attracting our lesser known native cavity-nesting bees. To remedy this paucity of data, we set up cavity nest boxes across fourteen locations in the greater Portland area and erected wooden posts with nest blocks at 3 different heights (0.5, 1.5, and 2.3 meters). To accommodate a diversity of bee species, cavity diameters ranged in size from 3.0 to 10.0 mm. From these nests, we collected data to determine nest occupancy, nest diameter size preferences, and percent bee and wasp occurrence rates. The overall nest height occupancy rates greatly varied amongst the fourteen locations, but overall the 2.3 m height had the greatest percent occupancy. Although the bees and wasps from the nests collected in 2019 have not yet emerged we estimate that the nests will yield about 68% bees and 32% wasps. Lastly, the greatest occupancy rates were observed in the two smallest cavity diameters, 3.0 and 4.5 mm. Nesting preference data will be used to better inform residents of greater Portland how best to provide nesting habitat for cavity nesting bees, and the solitary wasps that use similar nesting sites.