The Lower Keys Marsh Rabbit (Sylvilagus palustris hefneri) is perhaps the most endangered species of rabbit currently known on earth. The Lower Keys Marsh Rabbit is a small-to-medium sized species. They average approximately 15 in. (380 mm) in length and 2.2-3.8 lbs. (1.0-1.7 kg) in weight. Their hind feet range from 2.5-3.1 in.( 65-80 mm) in length, and their ears range from 1.7-2.4 in.( 45- 62 mm) in length.
They are the smallest of the three marsh rabbit subspecies, the others being Sylvilagus palustris paludicola and Sylvilagus palustris palustris. These rabbits do not appear to be sexually dimorphic. The fur of The Lower Keys Marsh Rabbit is short with dark brown fur and a grayish-white belly, and their tails are dark brown.
The Lower Keys Marsh Rabbit Difference
They are smaller than the mainland marsh rabbit (S. p. palustris) and Upper Keys marsh rabbits (S. p. paludicola) and are distinguished by their dark fur. They also differ from S. p. palustris and S. p. paludicola in several cranial characteristics. The Lower Keys marsh rabbit has a shorter molariform tooth row, higher and more convex frontonasal profile, broader cranium.
They have been isolated to the Keys by the rise in sea level and human inhabitation to the local area. This isolation may be the cause for the specialization of the Upper Keys Marsh Rabbit. Research has determined the habitat occupied of The Lower Keys Marsh Rabbit to be 633 acres in 1995, with only 81 suitable habitats.
Lower Keys Marsh Rabbit Habitat Range
This range includes a few of the larger Lower Keys, specifically, Boca Chica, Saddlebunch, Sugarloaf, and Big Pine Keys and the small islands near these Keys. From 2001 to 2005, researchers surveyed the predetermined habitat to establish a current habitat range. They determined the median size of occupied patches was 5.25 acres. This data is representative of 112 patches of occupied habitat. It should be noted that this data represents an increased search area rather than an increased number of individuals of this rare species of animal. There was a net loss in patch occupancy between the 2001-2005 and 1988-1995 survey periods. Possible reasons attributing to this loss are stray cat predation, the rise in sea level, and storm surges from hurricanes.