Josh Adams

Effects of radiotransmitters on the reproductive performance of Cassin’s auklets

Abstract We examined whether radiotransmitters adversely affected the reproductive performance of Cassin’s auklets (Ptychoramphus aleuticus) breeding on the California Channel Islands during 1999-2001. We attached external radiotransmitters to 1 partner in 108 Cassin’s auklet pairs after nest initiation and used 131 unmarked, but handled, pairs as controls. Compared to alpha chicks raised by radiomarked pairs, alpha chicks raised by unmarked pairs had faster mass growth rates (1.95 ± 0.30 g d-1 vs. 3.37 ± 0.53 g d-1, respectively), faster wing growth rates (2.46 ± 0.10 mm d-1 vs. 2.85 ± 0.05 mm d-1), greater peak fledging masses (118.9 ± 3.5 g vs. 148.3 ± 2.4 g), and higher fledging success (61% vs. 90%). Fledging success was reduced more when we radiomarked the male (50% fledged) rather than the female partner (77% fledged). After fledging an alpha chick, unmarked pairs were more likely to initiate a second clutch (radiomarked: 7%; unmarked: 39%) but did not hatch a second egg (radiomarked: 4%; unmarked: 25%) or fledge a second (beta) chick (radiomarked: 4%; unmarked: 18%) significantly more often than radiomarked pairs. We resighted 12 radiomarked individuals nesting during a subsequent breeding season; each bird had shed its transmitter and healed the site of attachment. We suggest caution in using telemetry to evaluate the reproductive performance of alcids, but marking only females may minimize adverse effects.

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

Abstract We radio-marked 99 Cassins 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 California Resumen. 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.

Population divergence and gene flow in an endangered and highly mobile seabird

Seabirds are highly vagile and can disperse up to thousands of kilometers, making it difficult to identify the factors that promote isolation between populations. The endemic Hawaiian petrel (Pterodroma sandwichensis) is one such species. Today it is endangered, and known to breed only on the islands of Hawaii, Maui, Lanai and Kauai. Historical records indicate that a large population formerly bred on Molokai as well, but this population has recently been extirpated. Given the great dispersal potential of these petrels, it remains unclear if populations are genetically distinct and which factors may contribute to isolation between them. We sampled petrels from across their range, including individuals from the presumably extirpated Molokai population. We sequenced 524 bp of mitochondrial DNA, 741 bp from three nuclear introns, and genotyped 18 microsatellite loci in order to examine the patterns of divergence in this species and to investigate the potential underlying mechanisms. Both mitochondrial and nuclear data sets indicated significant genetic differentiation among all modern populations, but no differentiation was found between historic samples from Molokai and modern birds from Lanai. Population-specific nonbreeding distribution and strong natal philopatry may reduce gene flow between populations. However, the lack of population structure between extirpated Molokai birds and modern birds on Lanai indicates that there was substantial gene flow between these populations and that petrels may be able to overcome barriers to dispersal prior to complete extirpation. Hawaiian petrel populations could be considered distinct management units, however, the dwindling population on Hawaii may require translocation to prevent extirpation in the near future.

Factors Influencing the At-Sea Distribution of Cassin's Auklets (Ptychoramphus aleuticus) that Breed in the Channel Islands, California

ABSTRACT. We used radiotelemetry to evaluate at-sea habitat use by Cassins Auklets (Ptychoramphus aleuticus) that bred at Prince Island, off southern California, from 1999 through 2001. We used logistic regression to compare paired radiotelemetry (presence) with random (pseudo-absence) location-associated habitat variables derived from (1) satellite remote-sensing of sea surface temperature and chlorophyll-a concentration and (2) bathymetry. Compared with random locations within their foraging area and after controlling for distance to colony, odds ratios indicated that Cassins Auklets with dependent young occurred in relatively shallower, warmer, and chlorophyll-rich water associated with chlorophyll fronts near the insular shelf break. These oceanographic features characterize habitats that support key euphausiid prey (e.g., Thysanoessa spinifera) and also other krill predators. Radiotelemetry combined with satellite remote-sensing of the ocean provides an alternative to vessel-based surveys for evaluating seabird foraging habitats. In the absence of information on the actual distribution, abundance, and, hence, availability of Zooplankton prey for seabirds, environmental factors can serve as proxies to help elucidate distributional patterns of seabirds at sea.

Stomach Contents of a Cuvier's Beaked Whale (Ziphius cavirostris) Stranded in Monterey Bay, California

From 1942 to 2010 there were 23 reported strandings of Cuvier’s Beaked Whale, Ziphius cavirostris (Odontoceti: Ziphiidae), in the Pacific Northwest (Oregon and Washington), and 25 reported strandings in California between 1982 and 2010 (Moore and Barlow 2013). Although Z. cavirostris appears to be the most cosmopolitan of the beaked whales, occurring in all oceans except in high polar regions (Leatherwood and Reeves 1983; Heyning 1989), global phylogenetic analyses reveal low maternal gene flow among populations confined to isolated ocean basins (Dalebout and others 2005). Extensive surveys throughout the California Current System (CCS) show that Z. cavirostris is distributed offshore over the continental slope, occurring more frequently closer to shore and aggregated in areas of complex bathymetry (for example, Monterey Bay, California and within the Southern California Bight, see Fig. 2 in Moore and Barlow 2013). In the northern CCS, Moore and Barlow (2013) estimated that the Z. cavirostris population likely has decreased by approximately 30% from 10,771 in 1991 to approximately 7550 individuals in 2008, and they suggested that one potential cause could be ecosystem change, thus highlighting the need for additional information on food habits. Heyning (1989) first summarized prey information for Z. cavirostris from around the world, a list that included 10 cephalopod families (16 genera), gadiform and atheriniform fishes, and 2 accounts of crustacean prey. Santos and others (2001) reported prey remains from 3 Z. cavirostris stranded in the eastern Atlantic and provided a review of known prey remains for the species. MacLeod and others (2003) extended the review of Santos and others (2001) to include comparison of Z. cavirostris with 2 additional beaked whales: Mesoplodon spp. and Hyperoodon planifrons. Combining these records with 7 Z. cavirostris stomachs evaluated by Santos and others (2007), the known diet of Z. cavirostris is based on prey remains recovered from only 45 individuals world-wide; diets consisted of 46 cephalopod species (15 families), infrequent crustacean remains, and rare representation among mostly unidentified fishes (MacLeod and others 2003). Compared with records from the Atlantic, food habits of Z. cavirostris off Alaska and in the eastern North Pacific are less well known (n 5 5 individuals, and only 1 from California). Fiscus (1997) identified 6 cephalopod families (11 genera) from a subset of the stomach remains collected and described by Kenyon (1961) from a mature female Z. cavirostris that stranded in March 1959 on Amchitka Island, Aleutian Islands, Alaska. Foster and Hare (1990) identified 3 of the same cephalopod families (4 genera) as reported by Fiscus (1997) from a Z. cavirostris stranded in Kodiak, Alaska. In the Gulf of Mexico, Fertl and others (1997) identified a single beak of Loligo peali from an individual that stranded in Texas. An adult female Z. cavirostris (Moss Landing Marine Laboratory Museum [MLMLM] #499, standard length 600 cm) stranded dead on 15 January 1998 at Marina State Beach, California (UTM: Zone 10S, 607191E, 4062264N, WGS84). During a 2-d field necropsy, to minimize the loss of contents, we tied-off both the esophageal and duodenal ends of the stomach before removing it on 16 January 1998. Prey remains were also collected from the whale’s oral cavity. The stomach contents from 5 pyloric compartments (see Kenyon 1961 for a description of the stomach of an adult female Z. cavirostris) were gently rinsed and sifted through a 500-mm sieve. Cephalopod remains (whole beaks, beak fragments, and eye lenses) and fish remains (bones and eye lenses) were preserved in 50% isopropyl alcohol and fish otoliths were stored dry. Cephalopods were identified to lowest taxon using the GENERAL NOTES

Carotenoid-based skin ornaments reflect foraging propensity in a seabird, Sula leucogaster.

Carotenoid-based ornaments are common signalling features in animals. It has long been proposed that such ornaments communicate information about foraging abilities to potential mates. However, evidence linking foraging with ornamentation is largely missing from unmanipulated, free-ranging populations. To investigate this relationship, we studied a coastal population of brown booby (Sula leucogaster brewsteri), a seabird with a carotenoid-based gular skin ornament. δ13C values from both feathers and blood plasma were negatively correlated with male gular colour, indicating birds that consumed more pelagic prey in offshore locations had more ornamented skin than those that fed on nearshore, benthic prey. This relationship was supported by our GPS tracking results, which revealed longer, more offshore foraging trips among highly ornamented males. Our data show that brown booby ornaments are honest indicators of foraging propensity; a link consistent with the rarity hypothesis and potentially driven by the concentration of carotenoids found in phytoplankton versus benthic algae. Carotenoid-based ornaments may reflect foraging tendencies in animals such as coastal predators that use food webs with distinct carotenoid profiles.

Data for calculating population, collision and displacement vulnerability among marine birds of the California Current System associated with offshore wind energy infrastructure

With growing climate change concerns and energy constraints, there is an increasing need for renewable energy sources within the United States and globally. Looking forward, offshore wind-energy infrastructure (OWEI) has the potential to produce a significant proportion of the power needed to reach our Nation’s renewable energy goal. Offshore wind-energy sites can capitalize open areas within Federal waters that have persistent, high winds with large energy production potential. Although there are few locations in the California Current System (CCS) where it would be acceptable to build pile-mounted wind turbines in waters less than 50 m deep, the development of technology able to support deep-water OWEI (>200 m depth) could enable wind-energy production in the CCS. As with all human-use of the marine environment, understanding the potential impacts of wind-energy infrastructure on the marine ecosystem is an integral part of offshore wind-energy research and planning. Herein, we present a comprehensive database to quantify marine bird vulnerability to potential OWEI in the CCS (see https://doi.org/10.5066/F79C6VJ0). These data were used to quantify marine bird vulnerabilities at the population level. For 81 marine bird species present in the CCS, we created three vulnerability indices: Population Vulnerability, Collision Vulnerability, and Displacement Vulnerability. Population Vulnerability was used as a scaling factor to generate two comprehensive indicies: Population Collision Vulnerability (PCV) and Population Displacement Vulnerability (PDV). Within the CCS, pelicans, terns (Forster’s [Sterna forsteri], Caspian [Hydroprogne caspia], Elegant [Thalasseus elegans], and Least Tern [Sternula antillarum]), gulls (Western [Larus occidentalis] and Bonaparte’s Gull [Chroicocephalus philadelphia]), South Polar Skua (Stercorarius maccormicki), and Brandt’s Cormorant (Phalacrocorax penicillatus) had the greatest PCV scores. Brown Pelican (Pelicanus occidentalis) had the greatest overall PCV score. Some alcids (Scripps’s Murrelet [Synthliboramphus scrippsi], Marbled Murrelet [Brachyramphus marmoratus], and Tufted Puffin [Fratercula cirrhata]), terns (Elegant and Least Lern), and loons (Yellow-billed [Gavia adamsii] and Common Loon [G. immer]) had the greatest PDV scores. Ashy Storm-Petrel (Oceanodroma homochroa) had the greatest overall PDV score. To help inform decisions that will impact seabird conservation, vulnerability assessment results can now be combined with recent marine bird at-sea distribution and abundance data for the CCS to evaluate vulnerability areas where OWEI development is being considered. Lastly, it is important to note that as new information about seabird behavior and populations in the CCS becomes available, this database can be easily updated and modified. U.S. Geological Survey. Bureau of Ocean Energy Management.