The New Mexico Rare Arthropod Resource

Very little is known about the habitats and ecology of Perdita cara. In the Sevilleta National Refuge, the habitat is Chihuahuan Desert grassland (Kazenel et al. 2020). The Texas records were also taken within the Chihuahuan Desert. Species of Perdita are almost all oligolectic (Michener 2007). As such, their emergence is usually timed to coincide with the floral bloom period of their host plants (Wilson and Carril 2016). In Texas, this species was collected in early May, on Mesquite (Prosopis spp.), a tree in the pea family (Fabaceae) (Timberlake 1968), but host plant specificity is unknown.

Though the nesting habits of this species are unknown, Perdita generally nest in the soil, in branching that each ending in a single cell, which is more or less horizontal (Michener 2007). A few species nest gregariously, with females nesting in close proximity to one another (Wilson and Carril 2016). Other species are communal nesters, with more than one female sharing a nest entrance (Michener 2007), yet others are more solitary. Instead of covering nest cells in a water proof coating, like other species in the family Andrenidae do, Perdita cover only the spherical ball of pollen provisioned for larvae in a coating (Wilson and Carril 2016). Many species are specific about the soil type they choose to nest in (Wilson and Carril 2016). Adult emergency seems to be dependent on humidity levels which indicate significant rain events above ground, at least for desert species (Wilson and Carril 2016).

This species is found in the southwestern United States, where it has been collected at very few sites. It is known only from several localities within the Sevilleta National Wildlife Refuge, in New Mexico, and one locality in West Texas (Timberlake 1958, Chesshire et al. 2023). It is unclear if it has been recorded in Texas since 1954.

There are no conservation actions in place for this species. It is known to occur in at least on protected area, the Sevilleta National Wildlife Refuge, though it is not removed from the main threat of severe drought in this refuge. Research is needed to verify the species remains extant. In addition, a better understanding of the distribution, population size and trend, habitats and ecology, and threats is needed for this species.

The threats to this species are not well understood, though drought is likely the main threat. The Southwestern U.S. saw its driest 22-year period from 2000 to 2021, since at least 800 CE (the time period used in previous climatic reconstructions) (Williams et al. 2022). Droughts are projected to become more prolonged, severe, and common in the region under future climate change scenarios (USGCRP 2018). Drought may negatively impact bee species by reducing floral resource availability (Phillips et al. 2017). In addition, declines observed in Perdita species at one site the Chihuahuan Desert have been attributed to small body size of these bees, and associated sensitivity to heat and desiccation (Kazenel et al. 2024).

The population size and trend are not known for this species. Since the 1950s it has only been recorded from the Sevilleta National Wildlife Refuge, so it could be quite rare (Timberlake 1958).

• Williams, A.P., Cook, B.I. and Smerdon, J.E. . 2022. Rapid intensification of the emerging southwestern North American megadrought in 2020–2021. Nature Climate Change 12: (232-234).
• Timberlake P.H.. 1958. A revisional study of the bees of the genus Perdita F. Smith, with special reference to the fauna of the Pacific Coast (Hymenoptera, Apoidea) Part III. University of California Publications in Entomology 14: (303-410).
• Kazenel, M.R., Wright, K.W., Griswold, T., Whitney, K.D. and Rudgers, J.A.. 2024. Heat desiccation tolerances predict bee abundance under climate change. Nature 628: (342-362).
• Kazenel, M.R., Wright, K.W., Bettinelli, J., Griswold, T.L., Whitney, K.D. and Rudgers, J.A.. 2020. Predicting changes in bee assemblages following state transitions at North American dryland ecotones. Scientific Reports 10: (708).
• Phillips, B.B., Shaw, R.F., Holland, M.J., Fry, E.L., Bardgett, R.D., Bullock, J.M. and Osborne, J.L.. 2017. Drought reduces floral resources for pollinators. Global Change Biology 24: (3226-3235).
• Wilson, J.S. and Carril, O.M. 2016. The Bees in Your Backyard: A Guide to North America's Bees. Princeton University Press, Princeton, NJ .
• USGCRP. 2018. Impacts, Risks, and Adaptation in the United States: Fourth National Climate Assessment, Volume II. U.S. Global Change Research Program , Washington, DC, USA : (1515).
• Michener, D.C.. 2007. The Bees of the World. The Johns Hopkins University Press, Baltimore : (953).
• ITIS. 2024. Integrated Taxonomic Information System (ITIS). 2024. https://www.itis.gov/
• Chesshire, P.R., Fischer, E.E., Dowdy, N.J., Griswold, T.L., Hughes, A.C., Orr, M.C, Ascher, J.S. Guzman, L.M, Hung, K-L.J., Cobb, N.S. and McCabe, L.M.. 2023. Completeness analysis for over 3000 United States bee species identifies persistent data gap. Ecography e06584: (13-Jan).