USGS Science⌕ Search

Geology topics

Richard B. Lanctot

Publications and source records attributed to Richard B. Lanctot.

65 records · Page 4Linked to original sources
USGS1999

Harlequin Duck recovery from the Exxon Valdez oil spill: A population genetics perspective

Concerns about Harlequin Duck ( Histrionicus histrionicus ) population recovery following the Exxon Valdez oil spill led biologists to ask whether birds located in different molting and wintering areas belong to genetically distinct and, thus, demographically independent populations. Owing to the lack of direct observations of movements among marine areas, three classes of genetic markers that differed in mode of inheritance were used to evaluate the degree of genetic differentiation among wintering areas within Prince William Sound (PWS) and the Alaska Peninsula and Kodiak Archipelago (APKA). We could not reject the null hypothesis that the wintering aggregations within each region are composed of a single genetically panmictic population. Differences in genotype frequencies among wintering locations within PWS and APKA were low and nonsignificant for all three classes of markers. Furthermore, we saw no evidence for deviations in Hardy-Weinberg equilibrium or gametic disequilibrium between loci within a winter collection site as would be expected if these locales were composed of individuals from reproductively isolated (and genetically distinct) breeding locales. Finally, no evidence for significant structuring was noted between PWS and APKA. Lack of spatial genetic structuring could be due to the cumulative effects of low levels of gene flow over long time periods, low levels of gene flow by immature birds moving between marine habitats, or to episodic dispersal caused by habitat alteration (e.g. volcanic eruptions). Harlequin Ducks are likely to recolonize or enhance populations in areas recovering from environmental damage via emigration of birds from non-affected areas. Demographic studies suggest, however, that levels of movements are low, and that population recovery by emigration is a long-term process.

The Auk↗
USGS1998

Certainty of paternity and paternal investment in eastern bluebirds and tree swallows

Extra-pair paternity is common in many socially monogamous passerine birds with biparental care. Thus, males often invest in offspring to which they are not related. Models of optimal parental investment predict that, under certain assumptions, males should lower their investment in response to reduced certainty of paternity. We attempted to reduce certainty of paternity experimentally in two species, the eastern bluebird, S ialia sialis , and the tree swallow, Tachycineta bicolor , by temporarily removing fertile females on two mornings during egg laying. In both species, experimental males usually attempted to copulate with the female immediately after her reappearance, suggesting that they experienced the absence of their mate as a threat to their paternity. Experimental males copulated at a significantly higher rate than control males. However, contrary to the prediction of the model, experimental males did not invest less than control males in their offspring. There was no difference between experimental and control nests in the proportion of male feeds, male and female feeding rates, nestling growth and nestling condition and size at age 14 days. We argue that females might have restored the males’ confidence in paternity after the experiment by soliciting or accepting copulations. Alternatively, males may not reduce their effort, because the fitness costs to their own offspring may outweigh the benefits for the males, at least in populations where females cannot fully compensate for reduced male investment.

Animal Behaviour↗
USGS1998

Male traits, mating tactics and reproductive success in the buff-breasted sandpiper, Tryngites subruficollis

Buff-breasted sandpipers use a variety of mating tactics to acquire mates, including remaining at a single lek for most of the breeding season, attending multiple leks during the season, displaying solitarily or displaying both on leks and solitarily. We found that differences in body size, body condition, fluctuating asymmetry scores, wing coloration, territory location and behaviour (attraction, solicitation and agonistic) did not explain the observed variation in mating tactics used by males. Which males abandoned versus returned to leks was also not related to morphology or behaviour, and there was no tendency for males to join leks that were larger or smaller than the lek they abandoned. These results suggest that male desertion of leks was not dependent on a male's characteristics nor on the size of the lek he was presently attending. Males did join leks with larger males than their previous lek, perhaps to mate with females attracted to these larger 'hotshot' males. Males at both leks and solitary sites successfully mated. Lek tenure did not affect mating success, although lekking males appeared to mate more frequently than solitary males. Courtship disruption and to a lesser extent, female mimicry, were effective at preventing females from mating at leks, and may offer a partial explanation for female mating off leks. Our analysis that combined all males together within a year (regardless of mating tactic) indicated that males that attended leks for longer periods of time and that had fewer wing spots were significantly more likely to mate. Given some evidence that wing spotting declines with age, and that females inspect male underwings during courtship, the latter result suggests that female choice may play some role in determining male success. We suggest that male buff-breasted sandpipers may use alternative mating tactics more readily than males in other 'classic' lek-breeding species because: (1) unpredictable breeding conditions in this species' high arctic breeding range leads to low lek stability, which in turn hinders mate selection mechanisms mediated by male dominance and female choice; and (2) males are not constrained by morphological markings that indicate status or sex. Both characteristics may reduce the reproductive benefits associated with males adopting one mating tactic and result in a sort of scramble competition in which males switch between tactics as local conditions change.

Animal Behaviour↗
USGS1998

Sexual attitudes at northern latitudes

Spreading his wings to reveal their pearly white undersides, the male buff-breasted sandpiper tilted his head to the sky, puffed out his chest, and uttered a series of soft "tick-ticks.” He then proceeded to stamp his feet and vibrate his wings as if the ground were quaking beneath him. Soon, three females, attracted by this courtship display, entered the curve of his embracing wings. They then spread their own wings and turned so their backs were against his chest, each jostling for the position closest to him. Just when mating seemed inevitable, a neighboring male rushed into the group, forcing all the birds into the air.

Natural History↗
USGS1997

Lekking without a paradox in the buff-breasted sandpiper

Females in lek‐breeding species appear to copulate with a small subset of the available males. Such strong directional selection is predicted to decrease additive genetic variance in the preferred male traits, yet females continue to mate selectively, thus generating the lek paradox. In a study of buff‐breasted sandpipers ( Tryngites subruficollis ), we combine detailed behavioral observations with paternity analyses using single‐locus minisatellite DNA probes to provide the first evidence from a lek‐breeding species that the variance in male reproductive success is much lower than expected. In 17 and 30 broods sampled in two consecutive years, a minimum of 20 and 39 males, respectively, sired offspring. This low variance in male reproductive success resulted from effective use of alternative reproductive tactics by males, females mating with solitary males off leks, and multiple mating by females. Thus, the results of this study suggests that sexual selection through female choice is weak in buff‐breasted sandpipers. The behavior of other lek‐breeding birds is sufficiently similar to that of buff‐breasted sandpipers that paternity studies of those species should be conducted to determine whether leks generally are less paradoxical than they appear.

American Naturalist↗
USGS1997

Ephemeral lekking behavior in the buff-breasted sandpiper, Tryngites subruficollis

We studied male reproductive behavior of the buff-breasted sandpiper Tryngites subruficoills for three yean on a 16-km 2 study site in northern Alaska to document variation in male lekking behavior and to explore the causes of that variation. During the breeding season, about 75% of males on the study area displayed on leks, with the remainder displaying solitarily. Leks averaged between 2.3 and 3.0 males each (maximum size = 20). Most leks (69%) were present in only one year and about one-tenth were active all three years. Half of the leks were active for only one survey (maximum of 3-4 days) in a given year. Individual male behavior varied substantially, from remaining at a tingle lek for most of the breeding season or attending multiple leks during the season, to displaying solitarily or displaying both on leks and solitarily. Some males (30% or fewer) displayed near nests during the later part of the breeding season, perhaps attempting to copulate with females during egg-laying. The pro-portion of males that displayed on leks remained consistently high throughout the breeding season despite changes in the operational sex ratio and in the intensity of male-male competition. However, the absolute number of males (lekking and solitary) in the study area was positively correlated with the number of fertile females during both breeding seasons. We suggest that buff-breasted sandpipers may be unusual among lek-breeding birds in that males have the option of leaving areas when the number of fertile females becomes depressed and flying to new areas where breeding opportunities are still available. Breeding opportunities may be especially variable in the high arctic because of uneven snow accumulation and differential melt-off that can delay breeding by two or more weeks. This interpretation suggests that the mating system of the buff-breasted sandpiper must be viewed at a much larger scale than what has typically been used in mating system studies.

Alaska↗
USGS1994

Blood sampling in juvenile buff-breasted sandpipers: Movement, weight change and survival

The effect of blood sampling on juvenile Buff-breasted Sandpipers ( Tryngites subruficollis ) was evaluated by comparing movements, mass, and survival of 10 broods (37 chicks) that were bled and eight broods (31 chicks) that were not bled. Blood was sampled from the jugular vein of chicks when they weighed 9.1 ± 0.9 g (x̄ ± SD) on or within 1 d of hatch. Chicks showed few short-term negative effects from blood sampling. Individual chicks suffered little physical injury, and five of eight chicks where injury occurred (i.e., hematomas formed) survived to fledging. Furthermore, bled broods gained mass at a comparable rate during the first 5 d post-hatch, and were resighted at similar frequencies as broods that were not bled. Bled broods moved slightly longer distances than control broods 1 d after hatch, however. This increased activity may have been stress-induced, but was only temporary; bled and control broods made similar long-term movements, and the probability of resighting was similar at fledging. With the proper precautions, it appears that Buff-breasted Sandpiper young can be safely sampled for blood at an early age without causing undue harm.

Alaska↗
USGS1992

Density of loons in central Alaska

Loons breed across North America from the high arctic south to about 43 north latitude. (AOU 1983). Populations, particularly of Common Loons ( Gavia immer ) have recently declined in the continental U.S. and southern Canada (Sutcliff 1979, Titus and VanDruff 1981, McIntyre 1988). As a result, state and private natural resource organizations began more intensive monitoring of loon populations (in McIntyre 1986, Strong 1988). These surveys, however, are restricted to areas accessible by road, although recently aircraft were used for more remote areas (Lee and Arbuckle 1988, Strong 1990).

Alaska↗
USGS1991

A line transect model for aerial surveys

We employ a line transect method to estimate the density of the common and Pacific loon in the Yukon Flats National Wildlife Refuge from aerial survey data. Line transect methods have the advantage of automatically taking into account “visibility bias” due to detectability difference of animals at different distances from the transect line. However, line transect methods must overcome two difficulties when applied to inaccurate recording of sighting distances due to high travel speeds, so that in fact only a few reliable distance class counts are available. We propose a unimodal detection function that provides an estimate of the effective area lost due to the blind strip, under the assumption that a line of perfect detection exists parallel to the transect line. The unimodal detection function can also be applied when a blind strip is absent, and in certain instances when the maximum probability of detection is less than 100%. A simple bootstrap procedure to estimate standard error is illustrated. Finally, we present results from a small set of Monte Carlo experiments.

Alaska↗
USGS1991

Observations on habitat use, breeding chronology and parental care in Bristle-thighed Curlews on the Seward Peninsula, Alaska

Results from an intensive survey in 1989 of one of the two known breeding localities of Bristle-thighed Curlews Numenius tahitiensis are reported. During the pre-nesting period birds confined most of their activity to two vegetation communities: shrub meadow tundra and low shrub/tussock tundra. During nesting more than half the Curlews seen were observed on shrub meadow tundra, whilst during brood rearing, use of low shrub/tussock tundra continued to decline in importance as birds attending young increased their use of sedge wet meadows. Despite extensive searches no nests were located; however, observations of broods indicated that nest initiation began around 25 May and that hatching occurred during the last week of June. Detailed observations are presented on the formation of four brood-groups, some of which held different combinations of unrelated adults or young. The adaptive significance of this unusual wader behaviour is discussed.

Alaska↗