Jack M. Broughton

Widening diet breadth, declining foraging efficiency, and prehistoric harvest pressure: ichthyofaunal evidence from the Emeryville Shellmound, California

The Emeryville Shellmound is a famous but now destroyed midden once located on the east shore of San Francisco Bay. Analyses of the fish remains from the stratified late Holocene deposits indicate that prehistoric peoples had substantial impacts on the sturgeon populations of the Bay. This calls into question the commonly held belief that native peoples lived in harmony with nature and has important implications for the management of modern vertebrate populations.

Holocene environmental change, artiodactyl abundances, and human hunting strategies in the Great Basin

Despite a deep Great Basin tradition of incorporating paleoenvironmental change within ecologically oriented analyses of past human lifeways, there has been little attention focused on Holocene variation in artiodactyl abundances and the human hunting strategies dependent upon them. Here, we draw upon recently generated paleontological evidence from Homestead Cave of the Bonneville Basin to document a late Holocene artiodactyl population increase. We then use the prey model of foraging theory to predict late Holocene increases in the hunting of artiodactyls, relative to lagomorphs. That prediction is then tested against several fine-grained archaeological records of hunting behavior in the Bonneville Basin, Hogup Cave and Camels Back Cave, and a variety of more coarse-grained faunal records from throughout the Great Basin. Close fits are found between the deductively derived prediction and the empirical records of hunting behavior: dramatic proportional increases in artiodactyl hunting occurred during the late Holocene. The results have far-reaching implications for our understanding of prehistoric human adaptations in the Great Basin.

Showing-off, foraging models, and the ascendance of large-game hunting in the California Middle Archaic

In a recent paper in American Antiquity (2002:231-256), Hildebrandt and McGuire argue that archaeofaunal patterns in California document an ascendance of artiodactyl hunting during the Middle Archaic. They also suggest that such a trend is inconsistent with predictions derived from optimal-foraging models. Given the apparent failure of foraging theory, they advance a “showing off” model of large-game hunting. While their presentation is intriguing, we do not see a theoretical warrant for predicting that show-off hunting would have increased during the Middle Archaic. We present here an alternative hypothesis for the increase in artiodactyl abundances and the hunting-related patterns they identify. That hypothesis follows directly from the prey model itself under what appears to have been a dramatic artiodactyl population expansion after the drought-dominated middle Holocene period.

Prey body size and ranking in zooarchaeology: Theory, empirical evidence, and applications from the northern Great Basin

The use of body size as an index of prey rank in zooarchaeology has fostered a widely applied approach to understanding variability in foraging efficiency. This approach has, however, been critiqued—most recently by the suggestion that large prey have high probabilities of failed pursuits. Here, we clarify the logic and history of using body size as a measure of prey rank and summarize empirical data on the body size-return rate relationship. With few exceptions, these data document strong positive relationships between prey size and return rate. We then illustrate, with studies from the Great Basin, the utility of body size-based abundance indices (e.g., the Artiodactyl Index) when used as one component of multidimensional analyses of prehistoric diet breadth. We use foraging theory to derive predictions about Holocene variability in diet breadth and test those predictions using the Artiodactyl Index and over a dozen other archaeological indices. The results indicate close fits between the predictions and the data and thus support the use of body size-based abundance indices as measures of foraging efficiency. These conclusions have implications for reconstructions of Holocene trends in large game hunting in western North America and for zooarchaeological applications of foraging theory in general.

Size of the Bursa of Fabricius in Relation to Gonad Size and Age in Laysan and Black-Footed Albatrosses

Age determination can be difficult for birds that undergo little or no plumage change during life. This is the case for Laysan and Black-footed Albatrosses (Diomedea immutabilis and D. nigripes). The juvenile plumage for both these North Pacific albatrosses is completely grown by about five to six months of age, just prior to their first flight, and is largely indistinguishable from the definitive basic plumage. Consequently, no well-documented methods ofdistinguishing newly fledged birds, older pre-breeders, or breeding-aged adults has been described for these species (Harrison 1985). One potentially useful non-plumage-based technique of age determination involves the size of the bursa of Fabricius. The bursa is a dorsal diverticulum of the cloaca that performs an immunosuppressive function in immature birds (Glick 1983). In the few galliform birds in which the ontogeny of the bursa has been carefully described, the bursa begins to enlarge shortly after hatching and reaches a maximum size in four to six months. Soon after reaching peak size, the bursa decreases in size in a linear fashion. Involution is typically complete by the end of a birds first year of life. The bursa is greatly reduced in size or absent in adult birds (Glick 1983, Mercer-Oltjen and Woodward 1987, Mase and Oishi 1991). At least among galliforms, testosterone and progesterone have been demonstrated experimentally both to inhibit bursal development and stimulate bursa involution (e.g., Vujic et al. 1983, Mase and Oishi 1991). These findings may explain the inverse relationship between gonadal development and bursa size reported for a number of bird species (Kirkpatrick 1944, Davis 1947, Lewin 1963). Since bursa size is correlated with age, it has long been used in wildlife management settings to separate birds-of-the-year from breeding-age birds (e.g., Davis 1947, Henny et al. 1981). In addition, because the decrease in bursa size appears to be nearly linear for most species examined (but see Siegel-Causey 1990), the size of the bursa should provide information on age on an even finer scale. A series of banded known-age Laysan and Blackfooted Albatrosses were salvaged from North Pacific driftnet fisheries in 1990-1991. With these specimens, I have examined the relationship between age, bursa size, and gonad size. This is the first chronological study of bursa involution for species that are long-lived and have delayed sexual maturity. This analysis has implications concerning the use of the bursa of Fabricius for age determination in albatrosses and for our understanding of the endocrine influences on the reproductive biology of these species.

Prehistoric human impacts on California birds: evidence from the Emeryville Shellmound Avifauna

The abundance of artiodactyls, marine mammals, waterfowl, seabirds, and other animals in 18th- and 19th-century California astonished early explorers, and the incredible wildlife densities reported in their accounts are routinely taken as analogues for the original or pristine zoological condition. However, recent analyses of archaeological fish and mammal materials from California and elsewhere in western North America document that those early historic-period faunal landcsapes represent...

Terminal Pleistocene Fish Remains from Homestead Cave, Utah, and Implications for Fish Biogeography in the Bonneville Basin

Abstract Eleven fish species were identified from Homestead Cave, Utah. The remains, concentrated in the lowest stratum of the deposit, were accumulated by owls between approximately 11,200 and 10,100 14C yr B.P. and likely represent fish associated with the final die-off of the Lake Bonneville fauna. Four of the species (Salvelinus confluentus, Prosopium abyssicola, Catostomus discobolus, Richardsonius balteatus) represent their first records for Lake Bonneville. The S. confluentus premaxilla is the first Quaternary specimen record for the genus in the Great Basin and suggests a southern range extension during the Pleistocene. The C. discobolus specimens represent the first fossil records for the subgenus Pantosteus in the Great Basin; their presence in Lake Bonneville documents a Pleistocene connection between two presently disjunct populations. The hyomandibulars of Prosopium gemmifer are different from Recent specimens in a pattern suggesting Holocene introgression with Prosopium spilonotus. The lack of Cottus echinatus and the presence of both Cottus bairdi and Cottus extensus may suggest the former species evolved in Utah Lake over the last approximately 10,000 yr B.P. The abundance of Catostomus ardens and the absence of Chasmistes liorus may reflect a restricted spatial distribution of the latter in Lake Bonneville.