Karen S. Bollinger

PHYLOGEOGRAPHY OF CANADA GEESE (BRANTA CANADENSIS) IN WESTERN NORTH AMERICA

Abstract Using molecular genetic markers that differ in mode of inheritance and rate of evolution, we examined levels and partitioning of genetic variation for seven nominal subspecies (11 breeding populations) of Canada Geese (Branta canadensis) in western North America. Gene trees constructed from mtDNA control region sequence data show that subspecies of Canada Geese do not have distinct mtDNA. Large and small-bodied forms of Canada Geese were highly diverged (0.077 average sequence divergence) and represent monophyletic groups. A majority (65%) of 20 haplotypes resolved were observed in single breeding locales. However, within both large and small-bodied forms certain haplotypes occurred across multiple subspecies. Population trees for both nuclear (microsatellites) and mitochondrial markers were generally concordant and provide resolution of population and subspecific relationships indicating incomplete lineage sorting. All populations and subspecies were genetically diverged, but to varying degrees. Analyses of molecular variance, nested-clade and coalescencebased analyses of mtDNA suggest that both historical (past fragmentation) and contemporary forces have been important in shaping current spatial genetic distributions. Gene flow appears to be ongoing though at different rates, even among currently recognized subspecies. The efficacy of current subspecific taxonomy is discussed in light of hypothesized historical vicariance and current demographic trends of management and conservation concern.

TEMPORAL AND GEOGRAPHIC VARIATION IN SURVIVAL OF JUVENILE BLACK BRANT

Abstract First-year survival has important implications for the structure and growth of populations. We examined variation in seasonal survival of first-year Pacific Black Brant (Branta bernicla nigricans) marked late in summer in Alaska at two brood-rearing areas on the Yukon-Kuskokwim Delta (Tutakoke and Kokechik) and one area on the Arctic Coastal Plain to provide insight into the magnitude and timing of mortality during fall migration. First-year survival was lower in early fall (15 July–1 October), when birds fledged from brood-rearing areas and migrated to their primary fall staging area at Izembek Lagoon, Alaska, than during late fall and early winter (1 October–15 February), when birds made a long-distance transoceanic flight (>5000 km) to wintering areas in Baja California, Mexico. When compared to other years, monthly survival during early fall was 20–24% lower in 1992, the year of latest hatch dates and slowest growth of goslings. There was strong evidence to indicate that survival varied geographically within the early fall period. Monthly survival estimates during early fall were lowest for birds from Tutakoke, highest for birds from the Arctic Coastal Plain, and intermediate at Kokechik. Our findings revealed that most juvenile mortality occurred during the first 2 months following banding, and variation in juvenile survival during this period was likely influenced significantly by environmental parameters and habitat conditions on the breeding grounds. Monthly survival estimates during the subsequent 4 months were similar across geographic areas, and long-distance migration was likely the most important contributor to juvenile mortality during this period. Variación Temporal y Geográfica en la Supervivencia de Juveniles de Branta bernicla nigricans Resumen. La supervivencia durante el primer año de vida tiene implicancias importantes para la estructura y el crecimiento de las poblaciones. Examinamos la variación en la supervivencia estacional en individuos añales de Branta bernicla nigricans marcados al final del verano en Alaska en dos áreas de cría del Delta Yukon-Kuskokwim (Tutakoke y Kokechik) y un área en la planicie costera ártica para brindar información sobre la magnitud y el esquema temporal de mortalidad durante la migración de otoño. La supervivencia durante el primer año fue menor a principios del otoño (15 July–1 October), cuando las aves abandonaron las áreas de cría y migraron hacia el área principal de permanencia otoñal en Izembek Lagoon, Alaska, que durante fines de otoño y comienzos del invierno (1 October–15 February), cuando las aves realizaron un vuelo transoceánico de larga distancia (>5000 km) hacia las áreas de invernada en Baja California, México. Comparando con otros años, la supervivencia mensual durante principios del otoño fue un 20–24% menor en 1992, el año con fechas más tardías de eclosión y con crecimiento más lento de los polluelos. Hubo fuerte evidencia para indicar que la supervivencia varió geográficamente a principios del otoño. Las estimaciones mensuales de supervivencia durante principios del otoño fueron menores para las aves de Tutakoke, mayores para las aves de la planicie costera ártica, e intermedias para Kokechik. Nuestros resultados revelaron que la mayoría de la mortalidad juvenil ocurrió durante los dos primeros meses luego del anillado, y la variación en la supervivencia de los juveniles durante este período fue probablemente influenciada de forma significativa por parámetros ambientales y condiciones del hábitat en las áreas de cría. Las estimaciones mensuales de supervivencia durante los cuatro meses siguientes fueron similares para las distintas áreas geográficas, y la migración de larga distancia fue probablemente la causa más importante de mortalidad juvenil durante este período.

Using radiotelemetry to monitor cardiac response of free-living tule greater white-fronted geese (Anser albifrons elgasi) to human disturbance

Abstract We monitored the heart rates of free-living Tule Greater White-fronted Geese (Anser albifrons elgasi) during human disturbances on their wintering range in the Sacramento Valley of California during 1997. We used implanted radio transmitters to record the heart rates of geese as an observer experimentally approached them at a constant walking speed. On average, geese flushed when observers were 47 m (range: 25–100 m) away. Change point regression was used to identify the point in time when heart rate abruptly increased prior to flushing and when heart rate began to level off in flight after flushing. Heart rates of geese increased as the observer approached them during five of six disturbance trials, from 114.1 ± 6.6 beats/min during the observers initial approach to 154.8 ± 7.4 beats/min just prior to flushing at the first change point. On average, goose heart rates began to increase most rapidly 5 sec prior to taking flight, and continued to increase rapidly for 4 sec after flushing until reaching flight speed. Heart rate was 456.2 ± 8.4 beats/min at the second change point, which occurred immediately after flushing, and 448.3 ± 9.5 beats/min 1 min later during flight. Although goose heart rates increased as an observer approached, the largest physiological change occurred during a 9-sec period (range: 1.0–15.7 sec) immediately before and after flushing, when heart rates nearly tripled.

Behavioral correlates of heart rates of free-living Greater White-fronted Geese

We simultaneously monitored the heart rate and behavior of nine free-living Greater White-fronted Geese (Anser albifrons) on their wintering grounds in northern California. Heart rates of wild geese were monitored via abdominally-implanted radio transmitters with electrodes that received elcctrical impulses of the heart and emitted a radio signal with each ventricular contraction. Post-operative birds appeared to behave normally, readily rejoining flocks and flying up to 15 km daily from night-time roost sites to feed in surrounding agricultural fields. Heart rates varied significantly among individuals and among behaviors, and ranged from less than 100 beats per minute (BPM) during resting, to over 400 BPM during flight. Heart rates varied from 80 to 140 BPM during non-strenuous activities such as walking, feeding, and maintenance activities, to about 180 BPM when birds became alert, and ovcr 400 BPM when birds were startled, cven if they did not take flight. Postflight heart rate recovery time averaged < 10 sec. During agonistic encounters, heart rate exceeded 400 BPM: heart rates during social interactions were not predictable solely from postures, as heart rates were context-dependent, and were highest in initial encounters among individuals. Instantaneous measures of physiological parameters, such as heart rate, are often better indicators of the degree of response to external stimuli than visual obscrvations and can bc used to improve estimates of energy expenditure based solely on activity data.

REPRODUCTIVE STRATEGIES OF NORTHERN GEESE: WHY WAIT?

Abstract Migration and reproductive strategies in waterbirds are tightly linked, with timing of arrival and onset of nesting having important consequences for reproductive success. Whether migratory waterbirds are capital or income breeders is predicated by their spring migration schedule, how long they are on breeding areas before nesting, and how adapted they are to exploiting early spring foods at northern breeding areas. However, for most species, we know little about individual migration schedules, arrival times, and duration of residence on breeding areas before nesting. To document these relationships in a northern nesting goose, we radiotracked winter-marked Tule Greater White-fronted Geese (Anser albifrons elgasi; hereafter “Tule Geese”; n = 116) from the time of their arrival in Alaska through nesting. Tule Geese arrived on coastal feeding areas in mid-April and moved to nesting locations a week later. They initiated nests 15 days (range: 6–24 days) after arrival, a period roughly equivalent to the duration of rapid follicle growth. Tule Geese that arrived the earliest were more likely to nest than geese that arrived later; early arrivals also spent more time on the breeding grounds and nested earlier than geese that arrived later. The length of the prenesting period was comparable to that of other populations of this species, but longer than for goose species that initiate rapid follicle growth before arrival on the breeding grounds. We suggest that Tule Geese nesting in more temperate climates are more likely to delay breeding to exploit local food resources than Arctic-nesting species that may be constrained by short growing seasons. Estrategias Reproductivas de los Gansos del Norte: ¿Por Qué Esperar?

Using body mass dynamics to examine long-term habitat shifts of arctic-molting geese: evidence for ecological change

From 1976 onward, molting brant geese (Branta bernicla) within the Teshekpuk Lake Special Area, Alaska, shifted from inland, freshwater lakes toward coastal wetlands. Two hypotheses explained this redistribution: (1) ecological change: redistribution of molting brant reflects improvements in coastal foraging habitats, which have undergone a succession toward salt-tolerant plants due to increased coastal erosion and saltwater intrusion as induced by climate change or (2) interspecific competition: greater white-fronted geese (Anser albifrons) populations increased 12-fold at inland lakes, limiting food availability and forcing brant into coastal habitats. Both hypotheses presume that brant redistributions were driven by food availability; thus, body mass dynamics may provide insight into the relevance of these hypotheses. We compared body mass dynamics of molting brant across decades (1978, 1987–1992, 2005–2007) and, during 2005–2007, across habitats (coastal vs. inland). Brant lost body mass during molt in all three decades. At inland habitats, rates of mass loss progressively decreased by decade despite the increased number of greater white-fronted geese. These results do not support an interspecific competition hypothesis, instead suggesting that ecological change enhanced foraging habitats for brant. During 2005–2007, rates of mass loss did not vary by habitat. Thus, while habitats have improved from earlier decades, our results cannot distinguish between ecological changes at inland versus coastal habitats. However, we speculate that coastal forage quality has improved beyond that of inland habitats and that the body mass benefits of these higher quality foods are offset by the disproportionate number of brant now molting coastally.

Assessment of shoreline vegetation in relation to use by molting black brant Branta bernicla nigricans on the Alaska Coastal Plain

Abstract To evaluate the importance of large thaw lakes on the Alaska Coastal Plain for molting Pacific black brant Branta bernicla nigricans, distribution and life form of shoreline vegetation were assessed using several scales: satellite imagery, point-intercept transects, cover quadrats, and a parameter for water regime. Brant population and distribution estimates from aerial surveys were used to classify large lakes into high, moderate, and low use. Correlations between brant and abundance of their preferred feeding site — moss flats — were best demostrated by satellite imagery. Intercepts and cover ratings were not correlated, presumably because these techniques were less efficient at assessing area. General observations suggested that the presence of islands, large ice floes, and possibly other physical attributes of the habitat, influenced brant distribution. This area is unique because of low-lying, drained-lake basins that have ideal combinations of moss flats and large water areas where brant seek protection disturbance is vital to the success of this declining species because alternate habitats may not be available elsewhere on the Coastal Plain. in water or on ice floes. Protection of the area from

Black Brant from Alaska staging and wintering in Japan

Black Brant (Branta bernicla nigricans) nest in colonies in arctic Canada, Alaska, and Russia (Derksen and Ward 1993, Sedinger et al. 1993). Virtually the entire population stages in fall at Izembek Lagoon near the tip of the Alaska Peninsula (Bellrose 1976) before southward migration (Dau 1992) to winter habitats in British Columbia, Washington, Oregon, California, and Baja California (Subcommittee on Black Brant 1992). A small number of Black Brant winter in Japan, Korea, and China (Owen 1980). In Japan, 3,000-5,000 brant of unknown origin stop over in fall, and a declining population (< 1,000) of birds winter here, primarily in the northern islands (Brazil 1991, Miyabayashi et al. 1994). Here, we report sightings of brant in Japan that were marked in Alaska and propose a migration route based on historical and recent observations and weather patterns.

Morphological traits of Pacific Flyway Canada Geese as an aid to subspecies identification and management

Abstract Subspecies of Canada Geese (Branta canadensis) exhibit wide variation in body size across their range. To monitor harvest levels in the Pacific Flyway, biologists commonly use culmen length and plumage color to differentiate among subspecies on sympatric wintering grounds. Among the four large-bodied Pacific subspecies (B. c. parvipes, B. c. occidentalis, B. c. fulva, and B. c. moffitti), overlap in culmen length and subjectivity of visually assessing color results in misclassification and inaccurate harvest estimates. We examined the morphology of Pacific large-bodied Canada Geese to characterize body size variation among subspecies and provide more discriminatory measures for harvest assessments. We found that culmen length, one of the most commonly used field measures, overlapped widely among subspecies, and it had little support for inclusion in discriminatory models. Morphological measures with greater explanatory power included bill width at nail, bill width at base, head length, and mid wing. If culmen length and plumage color continue to be used to assess winter harvest, we recommend the addition of at least one sex-specific measurement to reduce levels of misclassification among subspecies. If an additional morphological measure is included, further evaluation on the wintering grounds should be conducted as this measures effectiveness may vary depending upon observer bias, temporal and spatial variation in subspecies abundance, and the proportion of birds accurately sexed by cloacal examination.

Traversing a boreal forest landscape: Summer movements of Tule Greater White-fronted Geese

Abstract We monitored the movement, distribution and site affinities of radio-marked Tule Greater White-fronted Geese (Anser albifrons elgasi) during spring and summer in Alaska, 1994-1997 and 2004. Our assessment of summer movements was comprehensive, as locations were obtained during prenesting, nesting, and molt for over 90% of geese with active radios captured during winter or the previous summer in Alaska. Geese arrived to coastal and interior marshes in the Cook Inlet Basin (CIB) from mid April to early May, after which they moved to nesting areas in the upper CIB. Nesting birds used coastal staging areas in close proximity to eventual nest site location. Molting sites included a sub-glacial lake system in the upper CIB, although up to 50% of geese underwent a molt migration to wetlands across the Alaska Range, 400-600 km west of the CIB. Geese that molted at distant sites returned to the CIB before autumn migration. Length of stay in the CIB varied among years from 108-119 days, and averaged 116 days. Summer home-range sizes, exclusive of molting areas, averaged >273,000 ha, and were substantially larger than reported for other northern-nesting waterfowl. No radio-marked geese were found nesting in the vicinity of Redoubt Bay on the west side of Cook Inlet, and few nested near the Susitna Flats, the only other previously known nesting areas. The absence of nesting geese from Redoubt Bay corroborates aerial survey data showing a precipitous decline in the use of the west side of Cook Inlet between the early 1980s and early 1990s. The change in distribution of geese is likely related to a major eruption of Redoubt Volcano in 1989 that significantly altered landscapes used by nesting, brood rearing, and molting geese in the vicinity of Redoubt Bay. High inter-site movements of Greater White-fronted Geese throughout summer in south central Alaska likely increases exposure to predation, but also promotes social interactions and facilitates pioneering of distant, and diverse habitats in a vast, patchy, and often unpredictable landscape.