Theodore Dru Alison Cockerell was a naturalist at the University of Colorado from 1904 to 1947 and studied botany, zoology, and paleontology in North and South America, Asia, Australia, Africa, and Europe. In the latter part of his career, he studied the California islands and published many papers on their natural history, 16 of them in four years (1937–1940). He made important contributions to the natural history of the islands in four distinct ways: entomology of the islands, including identification of a number of new species of bees; discovery of fossil marine invertebrate faunas and recognition that the zoogeography of the taxa reflects the position of the islands relative to converging cool and warm currents; discovery of abundant land snails, both living and in fossil form, and recognition that the fossils are in close stratigraphic association with mammoth fossils; and island biogeography, with considerations of species dispersal mechanisms and endemism. Newly discovered letters and memos also reveal that Cockerell played a pivotal role in the establishment of Channel Islands National Monument.

Archaeologists generally have not taken advantage of the distinctive characteristics of assemblages of shellfish remains from prehistoric sites to gain information about movement of people between sites within their territory. I attempt to demonstrate this potential through analysis of shell assemblages obtained through small-scale test excavation at 2 archaeological sites in the interior of Santa Cruz Island: CA-SCRI-796 in the western sector of the island and CA-SCRI-758 at an upland location in the central sector. An aspect of the data analysis focused on strata containing an abundance of red abalone shells, dating sometime between 3700 and 3350 cal BC at CA-SCRI-796 and sometime between 4900 and 4325 cal BC at CA-SCRI-758. Also considered are assemblages from later strata at CA-SCRI-758, dating between 2600 and 1600 cal BC. Alternative hypotheses to account for the differences between the sites in proportions of shellfish taxa represented are the following: differences in proportional abundances of taxa at the localities where site inhabitants collected shellfish, changes over time in the character of shellfish communities, different distances of the sites from sources of shellfish, and variation in the intensity of shellfish collecting. The first alternative appears to account for most of the differences between assemblages, thus providing information about the geographic extent of settlement systems.

Ideas concerning the initial peopling of the Baja California Peninsula have dramatically changed in recent decades. In the late 19th and early 20th centuries, the native inhabitants of the southern part of the Baja California Peninsula were believed by some to have come from Melanesia, based on the perceived similarity in skull morphology. Since the middle of the 20th century, most researchers propose that initial populations entered from the north by land, bringing with them 2 distinct cultural traditions. The first wave was thought to have been an incursion of Paleoindians with Clovis-type fluted points. The second wave refers to groups who occupied ancient lake shores, such as Laguna Seca Chapala, and who were considered as belonging to the Western Pluvial Lakes (WPL) tradition. Eventually people moved down to the southern tip of the peninsula, pushed by subsequent groups. The entry of human groups from the Mexican mainland across the islands in the central Gulf of California has also been suggested; early entries by other groups have been proposed as well. A migration from Australia to the Cape Region across the southern Pacific has also been argued. This paper summarizes recent archaeological evidence from radiocarbon dates, geomorphological settings, subsistence strategies, and material types and technologies indicating that Paleocoastal migrants may have reached the Cape Region during the Terminal Pleistocene. However, some of the early lithic artifacts and technologies in the Cape Region show similarities to the WPL tradition, such as leaf-shaped points, an eccentric crescent, and end and side scrapers. This evidence suggests that perhaps a Paleocoastal group and a WPL group reached the southern part of the peninsula at around the same time and that they had some kind of interrelation that is reflected in their lifestyles and materials, which were principally adapted to coastal life.

The damage and loss of coastal archaeological sites from shoreline transgression and other near-coastal processes is common around the world. It negatively impacts our ability to address important research questions including those about the colonization of the New World, which likely occurred along the Pacific Coast. Differences in geomorphic context, annual weather patterns, topography, vegetation, bedrock, and land-use history lead to distinct localized patterns of erosion even within small geographic regions. We assessed near-coastal erosion on Santa Rosa Island, California, by monitoring annual change at 16 controlled points on 11 archaeological sites from 2013 to 2017 and by comparing it to the local geomorphic context and annual weather patterns. Overall, erosion through this period was greatest on the northwest coast of the island, which is directly in the path of prevailing winds and most winter storms, and least on the more protected west and south coasts. The 2016–2017 winter was the rainiest and had the most annual erosion in general; however, erosion at sites along gulley walls was lowest that year. By monitoring annual erosion and weather and associating them with variations in erosional processes, we can better understand threats to valuable cultural resources and take appropriate steps for mitigating their losses and the loss of archaeological data.

The persistence of plastics in marine ecosystems and the physical hazards marine debris pose to wildlife have become issues of global concern. The Santa Barbara Channel is home to a number of important marine and coastal ecosystems, including the 5 islands of Channel Islands National Park, and has a variety of factors that influence marine debris accumulation. We examined the spatial variation of marine debris density and composition across the Santa Barbara Channel by quantifying marine debris on beaches of Santa Rosa and Santa Cruz Islands and the Ventura County mainland. Debris from surveyed beaches was cataloged, weighed, and measured to compare differences in island and mainland marine debris abundance, density, and composition. Derelict fishing gear accounted for a higher proportion of marine debris on island beaches compared to mainland beaches, and marine debris items on island beaches were significantly heavier compared to debris items on mainland beaches. The majority of debris on mainland beaches comprised smaller plastic fragments and single-use plastic items, and debris accumulation rates varied by season and location. Microplastics (plastic fibers and particles <5 mm) were found in the sand of all island and mainland beaches; however, density of microplastics did not appear to correlate with density of visually observable debris items (>25 mm) that were collected during marine debris cleanups. We compared our data from 2015 and 2016 with historical surveys performed from 1989 to 1994 to examine the temporal variation of marine debris on Santa Rosa Island. We found that there has been a significant increase in the amount of derelict fishing gear found on Santa Rosa Island over the past 27 years, which mirrors expansion of the California spiny lobster (Panulirus interruptus) fishery. This study highlights the importance of marine debris monitoring, as local changes in policy, fisheries, and consumer culture are reflected in accumulations of marine debris found on the California mainland and the uninhabited Channel Islands. Monitoring marine debris can provide insight into anthropogenic impacts and is a useful mechanism in monitoring the health of coastal and marine ecosystems.

We analyzed recreational and commercial catch records from 1980 to 2009 for the fishing blocks associated with the 5 southern offshore banks of the Southern California Bight (Cortes Bank, Tanner Bank, Northeast Bank, Cherry Ridge, and Garrett Ridge). Recreational fishers and divers targeted pelagic taxa (e.g., tunas and Yellowtail) but instead landed more benthic taxa (e.g., rockfishes, Ocean Whitefish, and California Sheephead). For the commercial fisheries, pelagics (Bluefin Tuna, Albacore, Skipjack, Yellowfin Tuna, Pacific Bonito, and Swordfish) were the most important taxa and represented a significant proportion (8%–27%) of the landings of these fishes in the bight. These fishes were caught primarily at Cortes and Tanner Banks, which together only represent 3.7% of the fishing grounds in the region. In addition, this proportion of catch of these critical species has been significantly increasing at the outer banks during this period. Based on their geography and physical oceanography, we propose that these offshore banks comprise a unique habitat for pelagic resources in the Southern California Bight.

The Island Night Lizard (Xantusia riversiana) was removed from the federal list of threatened species in May 2014. This strongly differentiated species is endemic to 3 of the southern California Channel Islands—San Clemente, San Nicolas, and Santa Barbara. Suitable habitat for Island Night Lizards is extensive on San Clemente Island, and the species is abundant there. Habitat is limited and fragmented, however, on San Nicolas Island and small Santa Barbara Island. Bringing together extensive field surveys and mark-recapture sampling, we synthesize available data for Island Night Lizards on San Nicolas Island and calculate population and density estimates for the species in major habitats on the island. Island Night Lizards are widely distributed across most of the eastern half of San Nicolas Island. In contrast, they are nearly absent over the western third of the island except for isolated populations in boulder beach habitats. We combined mark-recapture population estimates with comprehensive measurements of the extent of cactus, boxthorn, and other habitat types on the island to arrive at a more accurate assessment of the status of Island Night Lizards on San Nicolas Island. High densities of Island Night Lizards on the island are found in small areas of cholla cactus (Cylindropuntia prolifera; mean of 4100 lizards/ha), boulder beach habitat (mean of 3400 lizards/ha), and prickly pear cactus (Opuntia spp.; mean of 1700 lizards/ha); low numbers are found in more extensive mixed-shrub habitat (mean of 250 lizards/ha). The U.S. Fish and Wildlife Service requires a post-delisting program for “monitoring the overall health of the Island Night Lizard” to assure the continued long-term viability of the species in its restricted distribution. The information on population size and habitat presented here will inform and guide conservation and management efforts by the U.S. Navy on San Nicolas Island over the coming years.

We provide an update to the fossil avifauna of San Miguel and Santa Rosa Islands based on the identification of 3509 small bird bones recovered from fossil sites on Santa Rosa and from 3 archaeological-paleontological cave deposits and 20 fossil sites on San Miguel. This work adds 64 species to the fossil avian community of these 2 islands, increasing the previous total from 83 to 147 species, making this the richest Late Pleistocene–Holocene coastal avifaunal assemblage recorded for California. Of the 64 newly identified species, 62 are new additions to the Channel Islands fossil avifauna and 40 are new to the fossil avifauna of California. Twenty-two species were confirmed to have nested on San Miguel Island during the Holocene based on the identification of juvenile/immature bones. At least 4 land birds (Burrowing Owl [Athene cunicularia], Island Scrub-Jay [Aphelocoma insularis], Bewick's Wren [Thryomanes bewickii], and Spotted Towhee [Pipilo maculatus]) that nested prehistorically on San Miguel have disappeared from the modern record there. Island Scrub-Jay bones were identified from 3 fossil sites on San Miguel and 1 site on Santa Rosa, providing the first confirmation that this species lived on both islands during the Pleistocene and Holocene. Island Scrub-Jays disappeared from San Miguel Island sometime in the Late Holocene, but a small population may have lingered on Santa Rosa Island into historic times before dying out. Destruction of island scrub and woodland habitats following the introduction of livestock in the mid-19th century probably caused the extirpation of resident breeding populations of Bewick's Wren and Spotted Towhee from San Miguel Island and Island Scrub-Jay from Santa Rosa Island.

We summarized historical knowledge from 1912 to 1998 of 13 known breeding colonies of Ashy Storm-Petrels (Oceanodroma homochroa) at Santa Cruz Island, California. Breeding was first reported by naturalists at Painted Cave (1912), Scorpion Rocks (1928), and Orizaba Rock (1937). During early seabird colony surveys of the Channel Islands, breeding was also noted at Cavern Point Cove Caves (1970), Diablo Rocks (1976), and Gull Island (1977). During 1991–1998, more extensive surveys of nearly all sea caves and offshore rocks documented additional breeding at Bat Cave, Cave of the Birds' Eggs, Del Mar Cove Cave, Del Mar Rock, Dry Sandy Beach Cave, Shipwreck Cave, and Willows Anchorage Rocks. Historical impacts apparently occurred from specimen collecting and interference by other nesting seabirds; however, guano harvesting may have had major impacts on nesting habitats at Scorpion Rocks (main rock) and Orizaba Rock. Impacts from organochlorine pollutants were likely extensive, and population sizes at all colonies may have been lower in the 1960s and 1970s when organochlorine pollution was at its highest level. Standardized monthly nest monitoring during 1995–1998 was used to measure reproductive success and population size at 5 colonies, creating a baseline for long-term trend monitoring that has continued annually to 2016. Mist net captures were used to estimate population sizes at 2 colonies in 1991. Estimated population size for Santa Cruz Island in 1991–1998 was 338 pairs, greater than previously reported for 1976–1977 (45–55 pairs), but the more recent estimate includes more colonies (especially 3 large colonies in sea caves), different methods of estimation, and likely some recovery from impacts associated with organochlorine pollution.

Avian and mammalian predation of Ashy Storm-Petrels (Oceanodroma homochroa) were documented during monthly nest monitoring in 1995–1998 and 2005–2015 and once-per-year monitoring in 1999–2004 at 5 colonies at Santa Cruz Island, California. Throughout the study period, predation by Barn Owls (Tyto alba) was documented at the sea cave colonies, and at Orizaba Rock, and likely contributed to reduced breeding success at Bat Cave in 1995–1997. Recent predation by Common Ravens (Corvus corax) caused reduced breeding success each year in 2012–2015 at Orizaba Rock (35%–48%) and in 2013 and 2015 at Bat Cave (49%–52%). Raven predation appears to be developing into a larger long-term problem that may require additional management actions, but efforts have focused on deploying artificial nests at Bat Cave to provide more protected sites. Two sea cave colonies where skunks previously had not been detected experienced major adult mortality due to unusual predation events by island spotted skunks (Spilogale gracilis amphiala) in 2005 and 2008. At Bat Cave in 2005, 2 skunks were trapped after they had killed at least 76 Ashy Storm-Petrel adults. Prior to this mortality event, the colony contained 64–97 nests per year in 1995–1997, with low breeding success (49%–59%) related largely to organochlorine pollutants. After the skunks were caught, nest numbers increased from 19 in 2006 to 100 in 2015, with variable but generally higher breeding success (49%–90%). At Cavern Point Cove Caves in 2008, 2 skunks were trapped after killing at least 32 adults. Prior to the mortality event, this colony contained 11–17 nests per year in 1995–1997, with a lower breeding success rate of 20%–47%. Nest numbers increased from 2 in 2009 to 10 in 2015, with a variable but higher rate of breeding success (50%–80%). Skunk predation events may have been related to temporarily higher skunk populations at Santa Cruz due to low numbers of island foxes (Urocyon littoralis santacruzae). Deer mice (Peromyscus maniculatus santacruzae) were not significant predators of Ashy Storm-Petrels at Santa Cruz Island.

San Miguel Island (SMI) and its adjacent islets, Prince Island and Castle Rock, support a small population of Scripps's Murrelets (Synthliboramphus scrippsi) at the northwest limit of their breeding range. In 1994–1996, 2004, 2007, and 2015, we conducted at-sea surveys and nest searches to determine the breeding distribution and population size of the Scripps's Murrelet at the SMI group. During at-sea vocal surveys in 1994–1996, murrelet calls were heard at 4 stations around Prince Island (43–167 calls), 2 stations off Castle Rock (6 calls and 80 calls), and 4 stations off northeast SMI (5–123 calls), but none were detected at 8 stations off southern and northwestern SMI. At-sea spotlight surveys in 2004, 2007, and 2015 confirmed murrelet congregations off Prince Island and northeast SMI. Annual mean (±SD) spotlight counts on a standard transect off of northeast SMI and Prince Island were 9 ± 0 murrelets (n = 2) in 2004, 19 ± 4 (n = 3) in 2007, and 91 ± 15 (n = 2) in 2015; much higher spotlight counts at Prince Island accounted for the higher mean in 2015. We found murrelet nests in 4 of the 12 areas searched at SMI and Prince Island. In 2007 the first murrelet nests ever found on SMI proper were discovered at Harris Point, Bay Point, and Hoffman Point in isolated shoreline habitats that were inaccessible to endemic Island Foxes (Urocyon littoralis littoralis) but accessible to nonnative Black Rats (Rattus rattus). Using spotlight counts we estimated 100–263 breeding pairs at the SMI group in 2015, mainly at Prince Island (90%) where foxes and rats were absent. Spotlight surveys have not been conducted at Castle Rock, but <5 pairs were suspected. Introducing rats from SMI proper to the offshore islets is the most serious threat to murrelets at this remote island, although a large oil spill could also extirpate this population. Spotlight surveys and nest searches should be conducted at least every 5 years to confirm persistence of this vulnerable species at SMI and to detect major changes in population size.

San Clemente Island (SCI) supports one of the smallest Scripps's Murrelet (Synthliboramphus scrippsi; SCMU) colonies in the world, and perhaps the only colony of Guadalupe Murrelets (S. hypoleucus; GUMU) in California. In 2012–2016, the U.S. Navy sponsored development of a long-term murrelet monitoring program at SCI that utilized nocturnal spotlight surveys, night-lighting at-sea captures, and nest monitoring. Standardized spotlight survey transects were established in nearshore waters off breeding areas at Seal Cove and southeast SCI (SESCI). Baseline mean spotlight counts were 29 ± 15 murrelets (n = 31) at Seal Cove in 2013–2016 and 21 ± 10 murrelets (n = 15) at SESCI in 2014–2016. We banded 201 SCMU captured in congregations at Seal Cove (n = 158) and SESCI (n = 43); 12% of the SCMU from Seal Cove and 7% from SESCI were recaptured ≥1 year after banding. We also banded 21 GUMU at Seal Cove, but none were recaptured. Murrelet nests or eggs were found in 6 shoreline breeding “refuges” at Seal Cove and SESCI that were seldom if ever visited by island foxes (Urocyon littoralis clementae) and feral cats (Felis catus). Incubating SCMU were observed in 4 nest sites, but in 8 other sites only eggs or eggshells were found. Overall hatching success was very low (12%; n = 17 clutches) in 2012–2016, apparently due to intraspecific competition for limited nest crevices at Seal Cove and predation (or possibly abandonment and subsequent egg scavenging) by foxes or black rats (Rattus rattus) at SESCI. Using spotlight survey data, we estimated 115 murrelet pairs (range 79–208) at SCI, including 110 pairs (range 76–199) of SCMU and 5 pairs (range 3–9) of GUMU, although a GUMU nest has not yet been found. Power analyses of Seal Cove spotlight data indicated that surveys conducted over 9 nights per year for 20 years could reliably (power ≥ 0.90) detect minimum population changes of ±1.7% per annum. Additional efforts are needed to (1) confirm the breeding status of GUMU; (2) investigate alternative methods of rat control to increase hatching success in murrelet breeding refuges; and (3) enhance breeding habitats to reduce intraspecific competition for nest sites and increase the number of monitored nests.

Eight bat species were known and documented from the California Channel Islands when J.C. Von Bloeker (1967) presented at the First California Islands Symposium in 1965. Additional bat surveys by P.E. Brown (1980) in the 1970s resulted in “Distribution of bats of the California Channel Islands,” which was presented at the second symposium in 1978. Methods of detecting and identifying bats have changed over the past century. Museum collection methods using shotguns have been replaced by mist-netting and recording of echolocation calls. Currently, capture or acoustic records have identified 14 bat species (56% of the 25 species known to occur in California) on 6 of the 8 California Channel Islands, with occasional sightings of flying bats on Anacapa and San Miguel Islands. Bats now compose 78% of the native mammals on the islands (Collins 2012). Acoustic recording equipment has become smaller and easier to use in the field, and recorded echolocation signals are now recognized as valid “vouchers” if the species emits calls that are separable from others. For example, echolocation signals have identified western red bat (Lasiurus blossevillii), hoary bat (Lasiurus cinereus), western yellow bat (Lasiurus xanthinus), and Mexican free-tailed bat (Tadarida brasiliensis) from San Nicolas Island, and western mastiff bat (Eumops perotis) and canyon bat (Parastrellus hesperus) from Santa Cruz Island. Acoustic data have identified 3 new species for the California Channel Islands, as well as several new records on individual islands. As acoustic monitoring and other techniques are used more extensively, the number of species documented will increase and the proportions that are resident, vagrant, or transient on each island can be better resolved.

Capture-recapture methods are commonly used to estimate abundance and density of wild animal populations. Although a variety of sophisticated analytical techniques are available to evaluate capture-recapture data, vertebrate monitoring programs often lack the resources (e.g., time, personnel, and/or analytical expertise) to apply these methods. As an alternative, simple population indices, such as counts of unique individuals, may provide sufficient information to detect meaningful changes in population size. In this study we investigated whether a population index, easily generated from mark-recapture data under all conditions, might be used to provide valid ecological information for managers interested in long-term population trends of deer mice (Peromyscus maniculatus) on the California Channel Islands. In practice, determining the efficacy of estimating abundance from mark-recapture data and indices using empirical data (as opposed to simulated data) is difficult given the scarcity of long-term data sets that describe real populations. Using mark-recapture data that span 18 years (n = 122 trapping events, >12,000 marked individuals) for deer mice on 2 of the islands, we compared density estimates obtained from several commonly used mark-recapture models and also compared these estimates to index counts. Populations of island deer mice are extremely dynamic; estimated densities over the data period varied from 0 to >1200 mice/ha. Density estimates from models in program CAPTURE and program DENSITY, as well as from model-averaged Huggins models, were strongly correlated with each other and with the density index. Densities calculated by the models and the index showed similar patterns of population variation and trend over time for all 5 sites. For long-term population monitoring and assessment of population trends in deer mice, our findings suggest that the use of a simple index may provide adequate understanding of ecologically relevant population changes, though data collection methods that allow for more detailed analyses using advanced modeling techniques should be maintained.