Additional Reading 
Maya Volcanoes (p. 32) 
Based on extensive field studies of 
many of the earth’s important volca- 
noes and volcanic regions, F. Bullard’s 
Volcanoes of the Earth (Austin: Univer- 
sity of Texas Press, 1976) presents in 
nontechnical language current knowl- 
edge of volcanoes and their effects on 
the environment and people. This 579- 
page text, amply illustrated with photo- 
graphs, diagrams, and maps, includes a 
full-color section showing volcanoes 
and volcanic eruptions in many parts of 
the world. A summary of the prehistory 
of Chalchuapa, a major site in the Maya 
frontier region, R.J. Sharer’s “The Pre- 
history of the Southeastern Maya Pe- 
riphery” ( Current Anthropology, vol. 
15, pp. 165-87) establishes a basic chro- 
nology for occupation at the site and 
defines the sources of external influ- 
ences. Sharer also discusses changes in 
Chalchuapa brought about by the erup- 
tions ofllopango. “Chalchuapa: Inves- 
tigations at a Highland Maya Cere- 
monial Center,” also by Sharer 
{Expedition, Winter 1969, pp. 36-38), 
surveys some of the more significant re- 
sults of the University Museum’s ar- 
cheological research at El Trapiche, 
northeast of Chalchuapa. P. D. Sheets’s 
“An Ancient Natural Disaster” {Expe- 
dition, Fall 1971, pp. 24-31) recon- 
structs the nature and effects of the 
second-century Ilopango eruption, pro- 
posing that the thick layer of volcanic 
ash deposited over Chalchuapa ren- 
dered farm lands unusable and prompt- 
ed the emigration of groups of Proto- 
classic peoples to new areas. Sheets and 
D.K. Grayson edited Volcanic Activity 
and Human Ecology (New York: Aca- 
demic Press, 1979), a multidisciplinary 
collection of twenty articles exploring 
volcanic hazards and their adverse and 
beneficial effects on living organisms 
and the environment. This work in- 
cludes a chapter by Sheets, enriched by 
a very useful bibliography, on the cul- 
tural and environmental effects of the 
Ilopango eruption on Central America 
(pp. 525-64). Volcanism and the Prehis- 
tory of the Zapotitan Valley, El Salva- 
dor, edited by Sheets, will include the 
work of about twenty authors and cov- 
er the volcanic eruptions of the last 
2,000 years in central El Salvador. This 
archeological survey, scheduled to be 
published by the University of Texas 
Press, Austin, next year, will contain 
data from excavations at numerous 
sites in the Zapotitan Valley, including 
Ceren and Laguna Caldera. The Envi- 
ronment as Hazard, by I. Burton, R.W. 
Kates, and G.F. White (New York: Ox- 
ford University Press, 1978), is a multi- 
disciplinary summation of the whole 
range of experience associated with nat- 
ural disasters. 
Avocets and Stilts (p. 42) 
Even though the large, colorful avo- 
cet is a conspicuous, social bird with a 
wide distribution, it has received little 
ecological or behavioral study. One 
good account presenting information 
about avocet breeding biology, based 
on research done in the late sixties, is 
F. Gibson’s “The Breeding Biology of 
the American Avocet ( Recurvirostra 
americana) in Central Oregon” {Con- 
dor, vol. 73, pp. 444-54). Gibson, who 
observed avocets during three breeding 
seasons in an alkaline marsh, reports on 
the birds’ territorial system, courtship, 
nest building, egg laying, incubation, 
and hatching. R.B. Hamilton’s “Com- 
parative Behavior of the American 
Avocet and the Black-necked Stilt 
(Recurvirostridae)” {Ornithological 
Monographs no. 17, published by 
the American Ornithologists’ Union, 
1975), a summary of the biology of this 
family that includes detailed descrip- 
tions of behavioral displays, is virtually 
the only published study of black- 
necked stilt breeding behavior. Hamil- 
ton concludes that the numerous mor- 
phological and behavioral differences 
between these two closely related spe- 
cies correlate with habitat differences 
and probably reflect differences in their 
evolutionary histories. The Shorebirds 
of North America, edited by G.D. Stout 
(New York: Viking Press, 1967), con- 
tains accounts of species by R.S. Palm- 
er, a popular-style text by P. Matthies- 
sen describing habits and histories of 
the birds, and excellent color plates 
from paintings by R.V. Clem. Another 
general text is A.C. Bent’s Life Histor- 
ies of North American Shorebirds (New 
York: Dover Press, 1962), originally 
published in 1927 and still a standard 
reference for avian life histories. Bent’s 
text includes many fine descriptions of 
behavior, although as noted in the pres- 
ent account, he misinterprets avocet 
distraction behavior. Two books on 
predator-prey behavior are E. Curio’s 
The Ethology of Predation (New York: 
Springer- Verlag, 1976), a technical re- 
view of the predatory and antipreda- 
tory behaviors of animals, and R. 
Meinertzhagen’s Pirates and Predators 
(London: Oliver and Boyd, 1959), a 
colorful account of hunting behaviors 
of birds of prey around the world that 
typifies the “fang-and-claw” approach 
to biology. “Life at an Avocet Nest,” 
with photographs by M.M. Tremaine 
( Audubon , March 1975, pp. 68-75), is a 
short, staff-written photographic essay 
providing basic information about avo- 
cets. One of the twelve locations de- 
scribed in Roger Tory Peterson's Dozen 
Birding Hot Spots, by G.H. Harrison 
(New York: Simon and Shuster, 1976), 
is the Bear River Wildlife Refuge, one 
of the two study areas discussed in this 
issue’s article. 
Narwhals (p. 50) 
“Whether there is or is not an actual 
unicorn ... he cannot possibly be so 
fascinating or so important as the 
things men have dreamed and thought 
and written about him,” states O. Shep- 
ard in the introduction to The Lore of 
the Unicorn (Boston: George Allen and 
Unwin Ltd., 1978). Originally pub- 
lished in 1930, Shepard’s eloquent, il- 
lustrated study traces the long history 
of the legend of the unicorn, beginning 
with its first appearance in Western lit- 
erature in the fourth century a.d. 
Chapter nine, “Certainties” (pp. 
253-72), outlines the discovery of the 
“sea unicorn,” the narwhal, and the 
commercial history of its tusk. A large, 
informative volume that describes in 
detail thirty-three species, The Book of 
Whales, written and illustrated by R. 
Ellis (New York: Alfred A. Knopf, 
1980), includes a chapter summarizing 
basic knowledge of narwhal biology, 
the effect on the whale of hunting, and 
whale mortality (pp. 95-100). An illus- 
82 
