Monday, August 18, 2014

Celebrating 15 years of Beavers

Two of 5 new kits enjoy poplar leaves (July 2014)
This month Spring Farm Nature Sanctuary celebrates 15 years of continuous habitation by beavers. The original pair named Morton & Sarah, set up housekeeping here in August of 1999. During the pair's reign they created 6 ponds, several canals and 4 lodges. From 2001 - 2007 Sarah produced over 20 kits, including Julia, the colony's current matriarch. Julia was born in 2007 and was one 4 kits in Sarah's final litter. 
Morton & Sarah 
Sarah with one of the kits (perhaps Julia?) in summer of 2007
A kit wrestles with Morton
Morton still holds the preserve's record for cutting down the largest tree ever tackled by a beaver on the property. The Aspen tree's leafy crown made a perfect "textbook" landing in the stream. Despite popularly held beliefs, beavers often miss the water when they fall trees. Subject to wind and other factors, cut trees just as often fall away from the stream or pond and they sometimes get hung up in other tree branches and fail to hit the ground at all. However, Morton seemed to have unusually good aim and during his tenure he chalked up quite a decent batting average.    
The biggest Quaking Aspen on the property took about a week to fell
The large tree fell with its crown landing in the stream
The Bank lodge originally built by Morton in 1999 is still in use today
The 2nd lodge that Morton built also saw many years of use
Morton's dam on the 2nd Pond became our longest one, measuring over 200'
Not a pond, but a canal used to transport food and materials between ponds
Morton also built the most dams on the property and managed to construct the colony's most distant pond, which pushed close to the preserve's border. Two of the lodges that Morton originally built have been reused nearly every year. Although both have been renovated many times. The lodge currently occupied by our colony was one of his. 

Revealed by a dam breech - the original foundation stones laid down by Morton at the 2nd Pond dam
Following a major dam collapse that took place at the 2nd pond in 2012, the breech in the dam revealed interesting details of its original construction. I found a neat line of foundation stones that Morton had set in carefully across the stream bed in order to anchor later additions into place. As an animal architect he was unsurpassed. Following a similar dam collapse in 2006, Morton came up with the most innovative patch job that I had ever seen. Instead of making the patch a simple straight line between 2 sections of the dam, he created an oval patch which bowed way in toward the pond side, but also bowed out toward the down stream side. In the center of the oval structure was standing water. 
During the flood in 2006, the gap that opened up in the dam was at least 15 feet wide
Morton's "patented" oval shaped dam patch was quite innovative and it worked! 
Whereas a straight conventional patch would've taken less time, the more complex design served to divert the stream current away from the vulnerable patched area and distribute water pressure more evenly across the dam. Whether or not Morton had this particular design in his head when he set about his task, or if it just naturally evolved during the building process, no one can say. As a testament Morton's workmanship, the next time that same dam broke, it opened up in a completely different place. In subsequent years I've never seen the oval patch design repeated. Morton had at least 6 years of dam building experience at the time that he came up with it and he died the very next year, so the opportunity for him to use it again never arose. All I know is that when other beavers in the colony have been faced with similar dam breeches, they failed to employ Morton's design, and at least in the short term, failed to adequately repair their dams. Granted these instances involved younger and less experienced dam builders.
Morton taking a carrot break
Morton brings some Pussy Willow saplings into the pond - he was a great provider too
Morton (1998 - 2007)
Sarah with a kit in tow
Morton inspects the dam in late fall
Morton's offspring and their offspring continue to bolster the same structures that he began so many years ago

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