Having worked with several dozens of both D. couperi and D.m erebennus,in both the field and captivity, over the past 30 years and currently having 5.6 within my collection, I feel confident saying the behavior Steve has described is the exception, not the norm.
Actually, one of the most defensive displays I have ever witnessed by a Drymarchon spp.was that of a large male D. couperiI happened upon in South dade Co. many years ago. Also, I am aware of Zoo Atlanta once having a large male D. couperi, which was maintained within a large, walk-in enclosure complete with gopher tortoise burrows and gopher tortoises. Apparently, most keepers dreaded entering the enclosure, as the Indigo would literally shoot out of one of the enclosure's burrows and chase anyone entering the enclosure...
Best regards,
Jeff

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Jeff Snodgres
University of Arkansas
snodgresjeffreys@uams.edu
501.603.1947