Daniel W. Anderson

Brown pelicans: influence of food supply on reproduction

From 1970 through 1979, availability of northern anchovies Engraulis mordax, the major food source for breeding brown pelicans Pelecanus occidentalis californicus, was the most important determinant of fledging success. Once the birds are constrained to a breeding area, a weak relationship exists between large scale indices of anchovy abundance in the Southern California Bight (about 105 kM2) and mean pelican fledging rates. This relationship becomes much stronger if pelican feeding behavior and more localized areas associated with their breeding colonies (about 8 x 103 kM2) are considered separately. Anchovy abundance over small areas (about 2 x 103 km2) showed no relationship to pelican reproduction. This suggests that events which influence large geographic areas (such as weather-patterns) affect reproduction through prey levels. Yet, pelican reproductive output is more precisely related to local aspects of prey availability and abundance. Fledging rates are a suitable indicator of local food conditions because pelicans are constrained to more local feeding areas during breeding. High levels of annual variation in food supply result in high annual variations in pelican reproductive performance. Anchovy densities are greater near the two island areas where pelicans most commonly breed than mean density over the entire Southern California Bight. Other regions of high density in prey also exist during the pelican breeding season but they are probably not available to breeders. The locations of traditional breeding colonies most likely represent environmental situations where the combination of nesting substrate and attainable food supplies occur together with consistency.

Survival and dispersal of oiled brown pelicans after rehabilitation and release

Abstract California brown pelicans (Pelecanus occidentalis californicus) were exposed to oil spills just prior to the 1990 breeding season and during the 1991 breeding season in the Southern California Bight (SCB); some were captured, rehabilitated (cleaned and given veterinary care) and released (total = 31 colour- and radio-marked + 81 colour-marked only; = RHB). Nineteen unoiled controls (= CON) from the SCB population, but from an unaffected area, were captured, radio-marked (11) and/or colour-marked (8) in 1990. Despite extensive surveys in the Gulf of California and western Baja California (latitude 23° to 30°N), all radio signals, recoveries and sightings were on the Pacific Coast between 30° and 47°N from 1990–1992. After release and until radio-telemetry data ceased to provide a complete sampling of RHB and CON (after about 6 months), RHB pelicans disappeared at a higher rate than CON; a continuing lower survival of RHB was also indicated from independent sightings of colour-marked pelicans by late 1992. RHB pelicans showed no breeding activity (or even presence or association with breeding colonies) in both years. In contrast, expected proportions of radio-marked CON pelicans were active at breeding colonies in 1990, and the general brown pelican population (which acted as controls in 1991) was active at breeding colonies in 1991. Post-breeding dispersal occurred as expected (mostly to the north) in 1990 and 1991 with CON. RHB pelicans remained sedentary in the SCB for at least 5–6 months in 1990 but dispersed north ahead of CON (as expected for non-breeders) in 1991, apparently in response to building ENSO (El Nino/Southern Oscillation) conditions in the SCB 1991–1992. RHB pelicans (1990) tended to remain farther away from the breeding colonies than CON (1990) in their second post-rehabilitation breeding season. At that time, their dispersal behaviour was similar to that expected for non-breeding adults and juveniles. We conclude that oil and/or rescue and treatment result in long-term injury to brown pelicans, and that current efforts do not restore them to breeding condition or normal survivability.

An experimental soft-release of oil-spill rehabilitated American coots (Fulica americana): II. Effects on health and blood parameters

The Unocal-Metrolink oil spill of 21 February 1995 resulted in approximately 7800 barrels of San Joaquin crude oil being deposited into the San Gabriel River in Huntington Beach, CA, USA. In order to determine long-term pathological effects of oil exposure and rehabilitation, hematological and serum biochemical parameters for both rehabilitated (RHB) American coots (Fulica americana) and reference (REF) coots were examined every 3-4 weeks (56, 81, 108 and 140 days post oil exposure) after birds were cleaned, rehabilitated and soft-released. Most significant differences in monthly comparisons between RHB and REF birds occurred 56 days following oil exposure. Total white blood cell (WBC) count, albumin:globulin (A:G) ratio and calcium concentration were higher in RHB birds compared to REF birds 56 days post oil exposure. In addition, mean cell hemoglobin (MCH), mean cell hemoglobin concentration (MCHC), alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase and creatine kinase activities, and creatinine, total protein (TP) and globulin concentrations were lower in RHB birds. Blood results from 56 days post oil exposure for RHB coots which subsequently died were compared to blood results from days 108 and 140 for REF coots which survived. Oiled and rehabilitated birds which died had significantly higher WBCs, packed cell volume, TP and globulin concentrations, and lower A:G ratio, MCH, MCHC, glucose and sodium concentrations compared to REF birds which survived. Blood result differences detected at 3-4-week intervals between RHB and REF survivors, and differences detected between RHB coots which died and REF coots which survived, suggested that RHB coots developed an inflammatory response (infectious or non-septic) and, concurrently, may have experienced decreased immune responsiveness. Additionally, RHB coots experienced either an iron (Fe) utilization or Fe metabolism problem. These pathophysiological mechanisms were consistent with increased hemosiderin (stored Fe) present in the liver, spleen and kidney of necropsied RHB birds, and may have contributed to RHB coot mortality. When blood parameter differences were examined for their impact on survival time, it was determined that RHB coots had shorter survival times if they had very high cholesterol (> or =449 mg/dl) or chloride (> or =110 MEQ/l) concentrations on day 56 post oil exposure. Interestingly, the lack of differences between RHB and REF coots from day 81 through day 140 suggested that, from a hematologic and clinical chemistry perspective, coots which were oiled, rehabilitated, released and survived at least 3.5 months could not be differentiated from wild (REF) coots. From these findings it appears that blood analysis, coupled with post-release survival data, may help discern reasons for increased mortality of oiled and rehabilitated birds, compared to non-oiled reference birds.

Recent Population Status of the American White Pelican: A Continental Perspective

Abstract Breeding bird surveys were conducted at most American White Pelican (Pelecanus erythrorhynchos) colonies in North America from 1979-81 and the number of American White Pelicans was estimated at >109,000 breeding individuals in 55 colonies. Although many pelican colonies have not been surveyed since the early 1980s, we present the most current survey numbers available for North American colonies. Using available data (1998-2001) and the North American Continental Divide to delineate eastern from western metapopulations, 27 colonies and 48,240 nests in the East and 15 colonies and 18,790 nests in the West were documented, giving a total of about 134,000 breeding pelicans in North America. The nest numbers of 20 eastern and western colonies that were surveyed during 1979-81 and again in 1998-2001 were also compared to determine if pelican numbers are changing. The number of AWPE nests in those colonies has more than doubled since the 1979-81 surveys. Because current data for colonies in part of the United States and much of Canada are lacking and about 20 years have passed since more complete surveys were done, we propose that regular and coordinated North American pelican surveys should be initiated.

Reproductive effects of nest-marking studies in an American white pelican colony

-In 1981 and 1982 we studied the reproductive success of American White Pelicans in the Klamath Basin of northern California. We observed that reproductive success at one colony (Lower Klamath) became reduced in 1981 when we entered that colony to collect eggs for chemical analysis and to mark nests for an assessment of nesting success. Those pelicans produced only 0.5 Y/N (young per nest attempt) contrasted to pelicans nesting at an undisturbed colony that produced about 1.2 Y/N. No colonies were entered in 1982 and both produced about 1.1 Y/N. We concluded that our activities (similar to those of many researchers) reduced the success of that one disturbed colony. We suggest that the sample-egg technique should not be used in American White Pelican colonies, in-colony activities should be very limited, and researchers in bird colonies should attempt more often to assess the effects of their own activities.

Seasonal and geographical variation of organochlorine residues in birds from northwest Mexico.

Eight species of birds (129 individuals) were collected from three agricultural areas with long histories of pesticide use in northwestern Mexico. Plucked carcasses were analyzed for organochlorine (OC) pesticides and polychlorobiphenyls (PCBs). DDE was found in all of the samples and at higher levels than other OCs. Mean (geometric) DDE concentrations varied from 0.04 (μg/g) ppm in mourning doves (Zenaida macroura) to 5.05 ppm in double-crested cormorants (Phalacrocorax auritus). Hexachlorocyclohexane (HCH) was detected in 95% of the samples, but at lower levels than DDE. Hexachlorobenzene (HCB) residues were detected more frequently in birds from Mexicali (62%, p < 0.05) than in those from Yaqui and Culiacan. HCH and HCB concentrations were significantly higher in birds from Mexicali during the winter than in the summer (p < 0.05), indicating accumulation of these compounds during that period. Other OCs such as DDT, DDD, dieldrin, oxychlordane, heptachlor epoxide, endosulfan, and endrin were found at lower levels and less frequently. PCBs (quantitated as Aroclor® 1260) were found mostly in cattle egrets (Bubulcus ibis) and cormorants at the three locations. Overall, concentrations of OCs were higher for Mexicali than for Yaqui and Culiacan (p < 0.01). In a few cases, DDE levels were above those that might adversely affect birds.

Genetic variation, population structure, and evolution of California quail

We studied the genetic population structure of California Quail (Callipepla californica). This relatively sedentary gallinaceous species has differentiated geographically in ecological features and morphology. In California and Baja California, we obtained samples of quail (101 total birds) from a total of seven sites representing six of the eight recognized subspecies. We analyzed genetic variation at 37 protein-coding loci using starch gel electrophoresis. Levels of within population genetic variation, such as average heterozygosity per individual (3.2%), percentage of loci polymorphic (18.1%), and mean number of alleles per locus (1.32), are similar to values reported for other birds, both passerines and nonpasserines. Genotypic distributions did not differ significantly from Hardy-Weinberg expectations. Geographic partitioning of genetic variation was slight. Fsr (3.2%) and pairwise genetic distances among samples (D = 0.005) indicated little among-sample divergence, although statistically significant geographic heterogeneity was detected at four loci. Using Slatkins (1985a) method to estimate levels of gene flow, our data indicated that populations receive an average of 5.5 immigrants per generation. A UPGMA phenogram and a distance Wagner network indicated the existence of two weakly differentiated groups of samples, corresponding roughly to Baja California and California. However, a sample from California (Tule Lake) is genetically more similar to samples from Baja California than to its nearest geographic neighbors. We hypothesize that California Quail dispersed southward into Baja California subsequent to its junction three to five million years ago with southern California.

Selenium, boron, and heavy metals in birds from the Mexicali Valley, Baja California, Mexico.

Trace elements in irrigation drainwater in some areas of the southwestern United States have been detected at concentrations that are associated with reproductive, teratogenic and behavioral anomalies in birds. For example, increased bird mortalities were linked with high concentrations of selenium (Se) at the Kesterson Reservoir in California (Ohlendorf et aL 1986a). Agricultural ecosystems in northwestern Mexico resemble closely those of central and southern California because they are also intensively irrigated and there is concern that elevated concentrations of trace elements in these areas could also result in detrimental effects on resident and migratory birds and other wildlife. The Mexicali Valley is located in northeastern Baja California, south of the Imperial Valley in California. Approximately 70% of the cultivated land in Mexicali (182,000 hectares) is irrigated by gravity flow with water from the Colorado River (Secretaria de Agricultura y Recursos Hidraulicos 1984), and elevated concentrations of trace elements in agricultural drainwaters might be expected. Runoff is discharged directly to canals and to the Hardy River. The Hardy River also receives brine waste with potentially high concentrations of arsenic (As) and boron (B) from a geothermal energy plant located at Cerro Prieto in the middle of the agricultural valley, approximately 30 km south of the city of Mexicali (Comisi6n Federal de Electricidad 1987). There are no studies that evaluate the environmental hazards and concentrations of trace elements in wildlife of the Mexicali Valley, except for some data on fish and clams. Concentrations of mercury (Hg) in fish and clams from irrigation canals and drainages of the Mexicali Valley were measured to evaluate the extent of Hg contamination by the Cerro

THE LEGACY OF MERCURY CYCLING FROM MINING SOURCES IN AN AQUATIC ECOSYSTEM: FROM ORE TO ORGANISM

Clear Lake is the site of an abandoned mercury (Hg) mine (active intermittently from 1873 to 1957), now a U.S. Environmental Protection Agency Superfund Site. Mining activities, including bulldozing waste rock and tailings into the lake, resulted in approximately 100 Mg of Hg entering the lakes ecosystem. This series of papers represents the culmination of approximately 15 years of Hg-related studies on this ecosystem, following Hg from the ore body to the highest trophic levels. A series of physical, chemical, biological, and limnological studies elucidate how ongoing Hg loading to the lake is influenced by acid mine drainage and how wind-driven currents and baroclinic circulation patterns redistribute Hg throughout the lake. Methylmercury (MeHg) production in this system is controlled by both sulfate-reducing bacteria as well as newly identified iron-reducing bacteria. Sediment cores (dated with dichlorodiphenyldichlorethane [DDD], 210pb, and 14C) to approximately 250 cm depth (representing up to approximately 3000 years before present) elucidate a record of total Hg (TotHg) loading to the lake from natural sources and mining and demonstrate how MeHg remains stable at depth within the sediment column for decades to millenia. Core data also identify other stresses that have influenced the Clear Lake Basin especially over the past 150 years. Although Clear Lake is one of the most Hg-contaminated lakes in the world, biota do not exhibit MeHg concentrations as high as would be predicted based on the gross level of Hg loading. We compare Clear Lakes TotHg and MeHg concentrations with other sites worldwide and suggest several hypotheses to explain why this discrepancy exists. Based on our data, together with state and federal water and sediment quality criteria, we predict potential resulting environmental and human health effects and provide data that can assist remediation efforts.

Tissue distribution of trace elements and DDE in brown pelicans

Trace elements and organochlorine pollutants commonly occur in avian tissues. However, concentrations vary among species in the same geographic area, and some compounds can be distributed differently in body tissues among different species. In addition, some heavy metal concentrations vary with the birds age. The purpose of this paper was to obtain a sample of brown pelicans from these populations to determine which brown pelican tissues contain the highest concentrations of organochlorine pollutants and several trace elements, how much variation might exist in a general sample, and what interrelationships might exist among the tissues and compounds studied.