scholarly journals Foraging Distance and Home Range of Cassin's Auklets Nesting at two Colonies in the California Channel Islands

The Condor ◽  
2004 ◽  
Vol 106 (3) ◽  
pp. 618-637 ◽  
Author(s):  
Josh Adams ◽  
John Y. Takekawa ◽  
Harry R. Carter
Keyword(s):  
Home Range ◽  
Channel Islands ◽  
Santa Barbara Channel ◽  
Santa Barbara ◽  
Central California ◽  
Surface Warming ◽  
Foraging Distance ◽  
California Channel Islands ◽  
Ptychoramphus Aleuticus ◽  
Breeding Seasons

AbstractWe radio-marked 99 Cassin's Auklets (Ptychoramphus aleuticus) nesting at two colonies, Prince Island and Scorpion Rock, separated by 90 km in the California Channel Islands to quantify foraging distance, individual home-range area, and colony-based foraging areas during three consecutive breeding seasons. Auklets generally foraged <30 km from each colony in all years. Core foraging areas (50% fixed kernel) from Prince Island in 1999–2001 were north to northeast of the colony over the insular shelf near the shelfbreak. Core foraging areas from Scorpion Rock in 2000–2001 occurred in two focal areas: the Anacapa Passage, a narrow interisland passage adjacent to the colony, and over the southeastern Santa Barbara Channel. During 2000, intercolony foraging areas overlapped by 10%; however, auklets from each colony used the overlapping area at different times. Equivalent-sample-size resampling indicated Prince Island foraging area (1216 ± 654 km2) was twice that of Scorpion Rock (598 ± 204 km2). At Prince Island, mean individual distances, home-range areas, and colony-based activity areas were greater for females than males, especially during 2001. At Prince Island, core foraging areas of females and males, pooled separately, overlapped by 63% in 1999 and 2000, and by 35% in 2001. Postbreeding auklets from both colonies dispersed northward and moved to active upwelling centers off central California, coincident with decreased upwelling and sea-surface warming throughout the Santa Barbara Channel.Distancias de Forrajeo y Rangos de Hogar de Dos Colonias de Nidificación de Ptychoramphus aleuticus en las Islas del Canal de CaliforniaResumen. Para cuantificar la distancia de forrajeo, el área de hogar de los individuos y las áreas de forrajeo de las colonias, marcamos con radiotransmisores 99 individuos de la especie Ptychoramphus aleuticus que estaban anidando en dos colonias separadas por 90 km en las islas del Canal de California (Prince Island y Scorpion Rock) durante tres temporadas reproductivas consecutivas. Las aves generalmente forrajearon a menos de 30 km de cada colonia en todos los años. Las áreas núcleo de forrajeo (“kernel” fijo del 50%) de la colonia de Prince Island en 1999–2001 se ubicaron al norte y al noreste de la colonia, cerca del borde de la plataforma insular. Las áreas núcleo de la colonia de Scorpion Rock en 2000–2001 se ubicaron en dos áreas focales: el Pasaje de Anacapa, un estrecho corredor marítimo entre islas adyacente a la colonia, y en el sureste del Canal de Santa Barbara. Durante 2000, las áreas de forrajeo de las dos colonias se superpusieron en un 10%, pero las aves de cada colonia utilizaron las áreas de superposición en momentos diferentes. Análisis con tamaños de muestra equivalentes indicaron que el área de forrajeo de Prince Island (1216 ± 654 km2) era el doble de Scorpion Rock (598 ± 204 km2). En Prince Island, las distancias promedio entre individuos, el tamaño de los rangos de hogar y las áreas en que la colonia centró sus actividades fueron mayores para las hembras que para los machos, especialmente durante 2001. En Prince Island, las áreas núcleo de forrajeo de hembras y machos, combinadas separadamente, se superpusieron en un 63% en 1999 y 2000, y en un 35% en 2001. Las aves post-reproductivas de ambas colonias se dispersaron hacia el norte y se desplazaron hacia centros activos de surgencia en aguas de California central, de forma coincidente con una disminución en la surgencia y un calentamiento de la superficie del mar a través del Canal de Santa Barbara.

FORAGING DISTANCE AND HOME RANGE OF CASSIN'S AUKLETS NESTING AT TWO COLONIES IN THE CALIFORNIA CHANNEL ISLANDS

The Condor ◽  
10.1650/7428 ◽  
2004 ◽  
Vol 106 (3) ◽  
pp. 618 ◽  
Author(s):  
Josh Adams ◽  
John Y. Takekawa ◽  
Harry R. Carter
Keyword(s):  
Home Range ◽  
Channel Islands ◽  
Foraging Distance ◽  
California Channel Islands

The Origin of Island Mammoths and the Quaternary Land Bridge of the Northern Channel Islands, California

1978 ◽  
Vol 10 (2) ◽  
pp. 204-225 ◽  
Author(s):  
Donald Lee Johnson
Keyword(s):  
Late Quaternary ◽  
Channel Islands ◽  
Santa Barbara Channel ◽  
Santa Barbara ◽  
Land Bridge ◽  
Geological Evidence ◽  
Sea Levels ◽  
Environmental Setting ◽  
Northern Channel Islands ◽  
New Evidence

Pygmy proboscidean remains of Mammuthus exilis occur abundantly in late Quaternary deposits on the Northern Channel Islands, California. On the assumption that ancestral elephants could not have swum to the islands and must therefore have walked out, various land bridges have been hypothesized that link the northern islands to the mainland by a peninsula. Geological evidence for a land bridge, however, is lacking, and new evidence shows that elephants are excellent swimmers and skilled at crossing watergaps. The Santa Barbara Channel was narrowed to only 6 km during glacially lowered sea levels. Modern elephants swim much further, and at speeds ranging from 0.96–2.70 km/hr. Motives for California elephants to cross Pleistocene watergaps are inferred from motives that lead modern elephants in Asia and Africa to cross watergaps. These are the visual and olfactory sensing of islands and of insular food during times of drought or fire-induced food shortage. Diminutive size of M. exilis principally reflects lack of island predators, an adaption to periodic food stress in a finite forage area affected by periodic drought and fire, and an adaptation for keeping population numbers high to maintain genetic variability and to ensure survival despite accidents. A late Quaternary scenario describes the environmental setting of the Santa Barbara Channel and the conditions that led to proboscidean dispersal to the preexistent super-island Santarosae.

Complex Hunter-Gatherer-Fishers of Prehistoric California: Chiefs, Specialists, and Maritime Adaptations of the Channel Islands

1992 ◽  
Vol 57 (1) ◽  
pp. 60-84 ◽  
Author(s):  
Jeanne E. Arnold
Keyword(s):  
Cultural Evolution ◽  
New World ◽  
Channel Islands ◽  
Archaeological Research ◽  
Santa Barbara Channel ◽  
Santa Barbara ◽  
Wide Range ◽  
Maritime Adaptations ◽  
Channel Region ◽  
Lines Of Evidence

The Chumash of the Santa Barbara Channel region were among the most economically and politically complex hunter–gatherer cultures of the New World. In recent decades, rich ethnohistorical documents pertaining to Chumash culture were analyzed, thus providing an excellent foundation for understanding the simple chiefdom that was in place as explorers and missionaries arrived in the sixteenth to eighteenth centuries. Current archaeological research on the Channel Islands focuses on the emergence of ranked society in Chumash prehistory, with special emphasis on political developments and environmental stresses that contributed to cultural evolution. A wide range of data acquired from the Channel Islands illuminates a new model of the rise of complexity. This model of chiefdom emergence is based on population-resource imbalances, political opportunism, and the manipulation of labor by rising elites. Diverse lines of evidence must be employed to evaluate the timing, causes, and consequences of increasing complexity.

Prehistoric Marine Mammal Hunting on California's Northern Channel Islands

1998 ◽  
Vol 63 (4) ◽  
pp. 679-701 ◽  
Author(s):  
Roger H. Colten ◽  
Jeanne E. Arnold
Keyword(s):  
Marine Mammal ◽  
Marine Mammals ◽  
Large Body ◽  
Channel Islands ◽  
Santa Barbara Channel ◽  
Santa Barbara ◽  
Relative Contribution ◽  
Wide Range ◽  
Northern Channel Islands ◽  
Technological Developments

Prehistoric marine mammal hunting is of interest to archaeologists worldwide because these animals were exploited by a wide range of coastal societies. Sorting out the roles of particular groups of fauna in prehistoric economies requires detailed attention to the analysis of the entire faunal assemblage. Although marine mammals typically provided large quantities of fat and protein and were desirable prey, they were not always central to the diets of the groups that exploited them, particularly in temperate zones. To evaluate effectively the importance of marine mammal exploitation, scholars should calculate the relative contribution of these animals to the economy, identify changes in hunting techniques, determine the relationship between fauna and other aspects of society, assess changing environmental conditions, and consider alternate explanations for those relationships. A large body of research on the northern Channel Islands of California demonstrates that fishing was relatively more important than marine mammal exploitation in subsistence and in stimulating sociopolitical and technological developments. Recent attempts to credit marine mammal hunting as a driving force in the invention of the plank canoe and the evolution of a chiefdom in the Santa Barbara Channel area misunderstand environmental factors and site histories in this region. Rather than assuming that a pan-Pacific Coast set of traditions existed to exploit these taxa, we see evidence of local and regional differences rooted in variable cultural settings, physiographic and oceanographic conditions, and available technologies. Data from the Santa Barbara Channel are used to explore the relationships among marine mammal use, sociological change, and environmental change.

Health in Prehistoric Populations of the Santa Barbara Channel Islands

1993 ◽  
Vol 58 (3) ◽  
pp. 509-522 ◽  
Author(s):  
Patricia M. Lambert
Keyword(s):  
Protein Content ◽  
Skeletal Remains ◽  
Protein Deficiency ◽  
Intensive Agriculture ◽  
Channel Islands ◽  
Bone Lesions ◽  
Health Consequences ◽  
Santa Barbara Channel ◽  
Santa Barbara ◽  
Hunting And Gathering

Skeletal remains from the Santa Barbara Channel Islands, California were analyzed to evaluate the health consequences of an economic shift from a generalized maritime hunting-and-gathering adaptation to one focused increasingly on fishing. Changes in stature and in the frequency of inflammatory bone lesions suggest that health generally declined during this economic shift. This occurred despite an increase in the protein content of the diet. These data provide a basis for evaluating the significance of protein deficiency as a cause of the deterioration in health seen with the development of intensive agriculture.

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