Persico, L. and Meyer, G. 2009. Holocene beaver damming, fluvial geomorphology, and climate in Yellowstone National Park, Wyoming. Quaternary Research 71: 340-353.
Persico and Meyer (2009) used beaver-pond deposits and geomorphic characteristics of small streams to assess long-term effects of beavers and climate change on Holocene fluvial activity in northern Yellowstone National Park, which feat was accomplished by comparing the distribution of beaver-pond deposit ages to paleoclimatic proxy records in the region (approximately 44.9°N, 110.5°W). This work revealed that gaps in the beaver-pond deposit record from AD 1000 to 1300 were "contemporaneous with increased charcoal accumulation rates in Yellowstone lakes and peaks in fire-related debris-flow activity, inferred to reflect severe drought and warmer temperatures [our italics]." They also report that the lack of evidence for beaver activity during this period "is concurrent with the Medieval Climatic Anomaly," and they say that the severe droughts of this period "likely caused low to ephemeral discharges in smaller streams, as in modern severe drought [our italics]," implying that the Medieval Warm Period was likely just as dry and warm as it has been throughout the last few decades.