A DICHOTOMOUS KEY to the BATS OF CALIFORNIA’S CENTRAL COAST
1a. Interfemoral membrane lightly furred; fur uniformly black but many of the hairs are distinctly silver-tipped, especially on dorsum; and face NOT distinctly lighter than back, then
Lasionycteris noctivagans – Silver haired Bat
1b. If fur not as above; fur variously colored, go to #2
2a. Tail extending (usu.>30mm) beyond edge of interfemoral membrane, go to #3
2b. If no extension of tail beyond edge of interfemoral membrane, go to #4
3a. If forearm more than 70mm, then
Eumops perotis – Western Mastiff Bat
3b. If forearm less than 55mm, then
Tadarida brasiliensis – Mexican Free-tailed Bat
4a. If ears more than 20mm in height from notch to crown, go to #5
4b. If ears less than 20mm in height from notch to crown, go to #6
5a. If ears widely separated; hair yellow next to skin; forearm (radius) more than 46mm; and large-eyed, then
Antrozous pallidus – Pallid Bat
5b. If ears close together at anterior base, hair dark gray next to skin, and forearm less than 46mm, then
Corynorhinus townsendii pallescens – Western Big-Eared Bat
6a. Upper surface of interfemoral membrane bare, or if slightly furred, hairs of back not tipped with white, go to #8
6b. Upper surface of interfemoral membrane densely furred, go to #7
7a. Forearm more than 45 mm; silver-tips on some hairs, then
Aeorestes cinereus – Hoary Bat
7b. Forearm less than 45mm, brick red fur, then
Lasiurus blossevillii – Western Red Bat
8a. First visible tooth behind upper canine about 1/2 as high as the canine and in contact with it at base, go to #9
8b. First visible tooth behind the upper canine less than 1/3 as high as canine, or if 1/2 as high, then separated from the canine by a noticeable gap, go to #10
9a. Forearm more than 40 mm; tragus pointed, then
Eptesicus fuscus – Big Brown Bat
9b. Forearm less than 40 mm; tragus < 5 mm, blunt, and club-shaped, then
Parastrellus hesperus – Canyon Bat
10a. Dorsal surface of interfemoral membrane only furred on anterior half; foot <8 mm; dorsal fur glossy; wings and tail membrane black
Myotis ciliolabrum – Small Footed-Myotis
10b. Dorsal anterior surface of interfemoral membrane without dense fur, foot > 8.5 mm, go to #11
11a. Ear when laid forward extending > 2 mm beyond tip of nose; ear more than 16mm from notch to tip, go to #12
11b. Ear when laid forward extending < 2 mm beyond tip of nose; ear less than 16mm, go to #13
12a. With a fringe of stiff hairs on posterior edge of the interfemoral membrane, then
Myotis thysanodes – Fringed Myotis
12b. Without a conspicuous fringe of hairs on edge of interfemoral membrane; ears pitch black, opaque, 20-25mm, then
Myotis evotis – Long-eared Myotis
13a. Calcar with distinctive keel, go to #15
13b. Calcar without keel, go to #14
14a. Skull < 14 mm, total length, fur w/dull luster; body two-toned (darker on back, lighter on underside), then
Myotis yumanensis – Yuma Myotis
14b. Skull > 14 mm; fur usually glossy, then
Myotis lucifugus – Little Brown Myotis
15a. Forearm 37 mm or more, then
Myotis volans – Long-legged Myotis
15b. Forearm 35 mm or less, then
Myotis californicus – California Myotis