A New Mammal Big Day Record for North America

Humpback Whales near the Farallon Islands, California, on 4 August 2013.

On 4 August 2013, Peter Pyle (the mastermind), Sarah Allen and I made an all-out attempt to break the previous mammal “big day” record for North America of 17 native species, set independently by Peter Pyle and Richard Stallcup, in northern California. We began at Point Reyes at midnight and managed to break the record before dawn, recording our 18th species at 5:25 am! By the time we reached the dock in Sausalito at 7:15 am we had already tallied 21 species. We added 7 new seven species of marine mammals during a Debbie Shearwater pelagic trip to the Farallon Islands. After returning from the boat trip we spent another 6 hours searching for mammals but added only 2 more species, finishing our big day at 10:20 pm with 30 native mammals (29 detected by all; 3 heard only), 3 introduced mammals and 5 domesticated mammals. We used a bat detector, which converts ultrasound signals of bats to audible frequencies, to aid in the identification of bats at known roosts. Our biggest misses were Coyote, Badger, Gray Whale, Blue Whale, Sonoma Chipmunk and Muskrat. We journeyed 171 miles by car in a Toyota Prius, 90 miles by boat and 2 miles by foot. Here is our list of species in three categories, arranged by the time each was first detected:

NATIVE SPECIES
1) 00:01 Mule Deer
2) 00:06 Northern Elephant Seal
3) 00:12 Striped Skunk
4) 00:33 Raccoon
5) 00:50 Elk
6) 01:09 Brush Rabbit
7) 01:29 Deer Mouse
8) 01:33 Bobcat
9) 01:55 Pacific Jumping Mouse
10) 02:10 River Otter (heard only)
11) 03:11 Gray Fox
12) 03:35 Brazilian Free-tailed Bat
13) 03:41 Black-tailed Jackrabbit
14) 04:10 Pallid Bat
15) 04:15 California Myotis (heard only)
16) 04:18 Big Brown Bat
17) 04:48 Dusky-footed Woodrat (heard only)
18) 05:25 Townsend’s Big-eared Bat
19) 06:05 Harbor Seal
20) 06:11 California Vole
21) 06:55 Western Gray Squirrel
22) 08:20 Harbor Porpoise
23) 10:30 California Sea Lion
24) 10:30 Steller’s Sea Lion
25) 11:25 Northern Fur Seal
26) 12:02 Dall’s Porpoise
27) 12:31 Humpback Whale
28) 15:33 Pacific Bottlenose Dolphin
29) 18:18 California Ground Squirrel
30) 19:55 Yuma Myotis

INTRODUCED MAMMALS
31) 12:58 Virginia Opossum
32) 04:41 Fallow Deer
33) 05:25 Human

DOMESTICATED MAMMALS
34 00:30 Cattle
35 03:51 Dog (heard only)
36 05:05 Horse
37 05:57 House Cat
38 18:32 Goat

Floyd E. Hayes
Department of Biology
Pacific Union College
Angwin, California, USA