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Observations Requested for U.S. Fish and Wildlife Service Synthesis

Do you restore oak savanna in the Midwest? If you've noted complex interactions occurring as a result, Pauline Drobney, Prairie and Savanna Zone Biologist with the US Fish and Wildlife Serve, is interested in hearing your observations. Drobney and fellow wildlife biologist Rebecca Esser are working on a handbook for identifying and restoring oak savannas.  "The best indicators of condition and ecological health are those involving multiple taxa and abiotic conditions," notes Drobney. "They indicate processes are working. I'd like to find ways for savanna managers to be able to look for discrete signs of increasing health or degradation."

One example was recently shared on the Iowa Native Plants list serve by Sibylla Brown, who has noted Edwards' hairstreak butterflies in frequently burned oak dominated systems in southern Iowa:

According to Cech & Tudor’s Butterflies of the East Coast, '"Edwards' hairstreaks are confined to low-growth scrub oak habitats with nearby ant colonies (principally, if not exclusively Formica integra)." The ants tend and protect Edwards’s larvae in exchange for sweet secretions.  The ant colonies are located not just where Edwards’s occur, but also where they can obtain an uninterrupted supply of ‘honeydew’-both during and after the Edwards’s brief larval period. The presence of tenant larval treehoppers and scale insects-which ants also attend-is thus important.  Attendant ants construct conical, ant hill-like shelters at the base of host trees, where older Edwards’ caterpillars rest during the day  At night, the caterpillars emerge to feed, escorted by protector ants.

If you have an observation to share, feel free to add a comment below, or contact Pauline Drobney.