Just a brief update to report that three or our six telemetered females (41, 39 and 53) have returned to the shelters where they have delivered broods in past years and all look quite heavy. Another, Female 66, is also stationary in a hollow log with a full abdomen but she did not reproduce last year and, since 2016 was our first year monitoring her, we don’t know where she has gestated in the past. Female 75, who did produce kids last year, is not heavy, still on the move, and looks like she will skip this year. Female 80 was on the hillside at the bluff but I have recently lost her radio signal. She was heavy and I could not palpate embryos when I replaced her transmitter in early June but she had lots of material in her GI tract which complicates the exam. Hopefully, her new transmitter has not failed…
Our females continue to often produce offspring during consecutive years, sometimes three years in a row before taking a year off. As mentioned before, this is not the norm for temperate-latitude pitvipers. While annual reproduction is common in the tropics where it never gets cold, the shorter warm season this far from the equator usually means that females need a year or two between broods to replace body fat before they can reproduce again. Conditions for our rattlesnakes are obviously quite good (even in past “drought” years), allowing them to replenish their weight quickly after losing 30%–50% of their body mass when they give birth.
Finally, I thought you’d find this photo interesting. Our big beautiful Male 37 was just in for his transmitter change two days ago and had obviously consumed a ground squirrel just before I captured him.
