Considered collectively, the fauna of the Sonoran province is
measurably distinctive (though less so than the flora), especially in
the habits of the organisms. The prevailing animals, like the plants
of extraneous type, evidently represent genera and species developed
under more humid conditions and adjusted to the arid province through a
long-continued and severe process of adaptation; and no fundamentally
distinct orders or types comparable with the cacti and torotes of
the vegetal realm are known. The prime requisite of animal life in
the province is ability to dispense with drinking, either habitually
or for long intervals, and to maintain structure and function in the
heated air despite the exceptionally small consumption of water;
the second requisite is ability to cooperate in the marvelously
complete solidarity of animal and vegetal life characteristic of
subdesert regions. No systematic studies have been made of special
structures in the animal bodies adapting them to retention of liquids,
either by storage (as in the stomach of the camel) or by diminished
evaporation, though the prevalence of practically nonperspiring
mammals, scale-covered reptiles, and chitin-coated insects suggests the
selection, if not the development, of the fitter genera and species
for the peculiar environment. Much more conspicuous are the characters
connected with cooperation in the ever severe but never eliminative
strife for existence in the sub-desert solidarity; the mammals are
either exceptionally swift like the antelope, exceptionally strong
like the local lion, exceptionally pugnacious and prolific like the
peccary, or exceptionally capable of subsisting on waterless sierras
like the bura and mountain goat; the reptiles are either exceptionally
swift like the rainbow-hued lizards, exceptionally armed like the
sluggish horned toads, exceptionally venomous like the rattlesnake,
or exceptionally repulsive, if not poisonous, like the Gila monster;
even the articulates avoid the mean, and are exceptionally swift,
exceptionally protective in form and coloring, exceptionally venomous
like the tarantula and scorpion and centipede, or exceptionally
intelligent like the farmer ant and the tarantula-hawk; while there is
apparently a considerable class of insects completely dependent on the
cooperation of plants for the perpetuation of their kind, including the
yucca moth and (undescribed) cactus beetle. Among plants the intense
individuality (which is the obverse of the enforced solidarity) is
expressed in thorns and heavily lacquered seeds and toxic principles;
among animals it is expressed by chitinous armament, as well as by
fleetness and fangs and deadly venom.
The larger land animals of Seriland proper are the mountain goat in
the higher sierras, the bura (or mule-deer) and the white-tail deer on
the mid-height plains and larger alluvial fans, with the antelope on
the lower and drier expanses. Associated with these are the ubiquitous
coyote, a puma, a jaguar of much local repute which roams the higher
rocky sites, and a peccary ranging from the coast over the alluvial
fans and mid-height plains of the mainland (though it is apparently
absent from Tiburon). Of the smaller mammals the hare (or jack-rabbit)
and rabbit are most conspicuous, while a long-tail nocturnal squirrel
abounds, its burrows and tunnels penetrating the plains of finer
debris so abundantly as to render these plains, especially on Tiburon,
impassable for horses and nearly so for men. The California quail
and the small Sonoran dove are fairly common; a moderate number of
small birds haunt the more humid belts, and there is a due proportion
of Mexican eagles and hawks of two or three forms, with still more
numerous vultures. Ants abound, dominating the insect life, while wasps
and spiders, with various flies and midges, gather about the vital
colonies of the drier plains and swarm in the moister belts. Horned
toads and various lizards—bright-colored and swift, or earth-tinted
and sluggish—are fairly abundant, while black-tail rattlesnakes haunt
the more luxuriant vegetation of fog zones, permanent waters, and
cienegas. On the whole, the land fauna of Seriland is much like that
of the province in general, though the various forms of life are less
abundant than the average, since all (except the abounding squirrel)
are sought for food by the omnivorous Seri; and the distribution, even
when relatively abundant, is woefully sparse, as befits the scant and
scattered vegetal foundation for the animal life.
Strongly contrasted with the meagerness of the land fauna is the
redundant aquatic fauna of that portion of the gulf washing the shores
of Seriland. Tiburon island is named from the sharks, said by some
explorers to have been seen by thousands along its coasts; these
voracious feeders find ample food in literal shoals and swarms of
smaller fishes; a not inconsiderable number of whales have survived the
early fisheries (one, estimated at 80 feet in length, was stranded in
Rada Ballena about 1887); while schools of porpoises play about Boca
Infierno and elsewhere, making easy prey of slower swimmers caught in
the tide-rips and gale-swept breakers. Proportionately abundant and
varied is the crustacean life; littoral mollusks cling to the ledges
exposed along all the rocky coast stretches, and the entire beach from
Punta Antigualla to Punta Ygnacio is banded by a practically continuous
bank of wave-cast molluscan shells, the shell-drift being often yards
in width and many inches in depth. Common crabs abound in many of the
coves, and a large lobster-like crab frequently comes up from deeper
bights and bottoms; oysters attach themselves to rocks and to the roots
of shrubby trees skirting protected bays like Rada Ballena, while
clams are numerous in all broad mud-flats, such as those of Laguna
la Cruz; and the pearl oyster was fished for centuries toward Punta
Tepopa, until the ferocity of the Seri put an end to the industry.
Especially abundant and large are the green turtles on which the Seri
chiefly subsist, leaving the shells scattered along the shore and about
rancherias in hundreds; while two land tortoises (_Gopherus agassizii_
and _Cinosternum sonorense_) range about the margins of the lagoons,
and one of these is alleged to enter the water freely.
The abundance of water-fowl is commensurate with that of the submarine
life. The pelican leads the avifauna in prominence if not in actual
numbers, breeding on Isla Tassne (Pelican island), and periodically
patrolling the whole of Bahia Kunkaak and El Infiernillo in lines and
platoons of military regularity; gulls are always in sight, and the
cormorant is common; while different ducks haunt several of the islets,
and the shores are promenaded by curlews, snipes, and other waders.
There is a corresponding wealth of plankton, which at low spring tide
with offshore gale covers acres of shallow littoral with squirming or
inert but always slimy life, the substratum for that of higher order;
and jellyfish and echinoids are cast up by nearly every wave, while
at night the surf rolls up the smooth strands in shimmering lines of
phosphorescent light. On the whole, the aquatic life teems in tropic
luxuriance and more than ordinary littoral variety; for the waters of
the gulf are warmed by radiation and conduction from its sun-parched
basin, while the concentrated tides distribute and stimulate the
species and keep the vital streams astir.