Migration Patterns and Conservation Needs of the American Snout

Conservation Issues American Snouts - generalists using many nectar sources Somewhat limited in host plant utilization to Hackberry but this genus of 60 – 70 species is widespread in temperate regions of Northern Hemisphere American Snout conservation usually not of concern General concern about habitat loss and use of pesticides

Seasonal Migration & Irregular Local Eastern Migrants - Range from southern California to the eastern U.S. as far north as NYC - Survives only mild winters - Overwinters in the southern part of their range and repopulates more northern areas each spring. - Also local irruptions and migrants in East – ex. July 1984 - 800 recorded in Ontario.

SW US - Epic American Snout migrations The American Snout is known for huge irruptions and mass migrations at irregular intervals in the Southwest, usually July through October. Two examples of many: August 1966 – Snout migrants were so numerous that street lights turned on in Tucson, Arizona September and early October, 1971 – Hundreds of Snouts invaded Franklin County, Kansas. Three and four individuals could be netted in a single swing. Researchers felt that these snouts probably originated in Texas.

Texas Tops All Stories! - September 1921 – An estimated more than 6 billion American Snouts passed over a 250 mile front - Perhaps 25 million per minute - This flight lasted 18 days. - A clue? 36.4 inches of rain fell in an 18-hour period a few weeks earlier.

Drought cycles in the arid SW US Spiny Hackberry (Celtis pallida) has adapted to unpredictable climate cycles by arresting development during extreme drought and then responding to significant summer rain by a flush of new leaves. Nectar producing plants also respond to rain events by producing new flowers American Snouts may adapt to drought conditions by entering diapause waiting for a flush of new growth.

Factors Triggering American Snout Migrations in the SW - Drought followed by heavy rain - Strong pulse of new foliage - Adult American Snout population exploiting the window of optimal condition. - Drought caused lower predation levels - Resulting defoliation over a wide area triggers regionwide dispersal