Early this morning, John Hawkinson tweeted :
Just saw a rabbit in Mid-Cambridge 20' off Mass Ave. When did this start?
Quite awhile ago, according to our go-to guy for matters Cantabrigian, Robert Winters :
There were rabbits sighted this past year off Harvard Street between Trowbridge & Ellery Sts. They're around.
Nat Tarbox  adds:
Walk around the river path near Harvard, there is a rabbit every ten feet.
Kathy C  reports:
last summer, cute bunnies in weedy parking lot at Mass Ave and Albany.
Siobhan Gallagher  cautions:
Look closely at them. Don't think they're our cottontails but, rather, an invasive breed.
- Cambridge