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At least 433 records · Page 24Linked to original sources
USGS1989

Extra-pair copulation in the greater white-fronted goose

Controlled experiments and quantitative field studies with both captive and wild waterfowl (Family Anatidae) have demonstrated that extra-pair copulations (EPCs, both forced and unforced) may be a viable alternative reproductive strategy for males (Mineau and Cooke 1979; Burns et al. 1980; Cheng et al. 1982, 1983; Afron 1985; Evarts and Williams 1987). In a review of EPCs in waterfowl, McKinney et al. (1983) stressed the need for additional information on the extent of such behavior in seemingly monogamous species of birds. Such information would increase our understanding of the extent of mixed reproductive strategies as formally hypothesized by Trivers (1972). Extra-pair copulations have been reported for only three of 22 (14%) species of geese and swans (Tribe Anserini), but are known to occur in 37 of 122 (30%) of the remaining species of waterfowl (McKinney et al. 1983, 1984; Welsh 1988). Socioecological differences between Anserini and most other anatids may provide insight into the evolution of extra-pair copulatory behavior, as male Anserini (unlike most other Anatidae) provide extensive parental care and maintain long-term pair bonds (Owen 1980, p. 76). Cuckolded male Anserini thus stand to lose more in the form of reproductive investment than other male anatids, which may invest less in a given clutch and generally have short-term pair bonds. I describe here an observation of extra-pair copulation in wild Greater White-fronted Geese (A nser albifrons frontalis ). The observation is significant not only because it augments our meager documentation of this behavior within the Anserini, but it is the first observation of such behavior in a noncolonial goose (Mineau and Cooke 1979, McKinney et al. 1983). The occurrence of EPC behavior in a dispersal-nesting goose is important, as proximity to potential mates has been hypothesized as a factor possibly selecting for EPC behavior in geese (McKinney et al. 1983) and other species of monogamous birds (Gladstone 1979, but see Westneat 1987).

Alaska↗
USGS1989

Reproductive performance of Rio Grande wild turkeys

Frequency, magnitude, and timing of reproduction in Rio Grande Wild Turkey ( Meleagris gallopavo intermedia ) hens were studied in northeastern Colorado in 1986 and 1987. All adults (n = 12) and 95% (n = 20) of yearlings were known to attempt nesting. Adults initiated first nest attempts earlier than yearlings in 1987 but not 1986. Adults and yearlings did not differ in clutch size or nesting success. There was an inverse relationship between clutch size and initiation date of first nests by adults. Clutch and egg size, however, were not related. Among yearlings, body mass at capture in February was positively correlated with subsequent nest-initiation date. Environmental and social stimuli, but not winter severity, are hypothesized proximate conditions regulating reproduction in this Wild Turkey population.

The Condor↗
USGS1989

Dispersal in the communally breeding groove-billed ani (Crotophaga sulcirostris)

We studied dispersal in a color-banded population of the Groove-billed Ani (Crotophaga sulcirostris) in Costa Rica. Eight percent of the young alive at the end of the breeding season bred on their natal territories the next year and 4% remained but did not breed. Thirteen percent dispersed successfully within the study area and bred in communal groups or simple pairs. The remaining 75% of the young birds disappeared from the study area. Young males remained in the study area as breeders more frequently than did young females. Breeding dispersal occurred, with at least 9% of the adult population moving to a new territory each year.We used a demographic model to estimate the following dispersal fates for young birds. For both males and females, 62% of the young alive at the end of the breeding season in which they hatched obtained a breeding position the next year. Of those that dispersed from their natal territories, 59 to 70% of the males and 64 to 74% of the females obtained breeding positions. Of those that bred the year after they hatched, 22% of the males and 2% of the females bred in their natal units, 34% of the males and 6% of the females bred within the study area but outside their natal units, and 44% of the males and 92% of the females bred outside the study area. We estimated that all of the males and 28% of the females that bred the year after they hatched were within three territories of their natal sites.

Condor↗
USGS1991

Flight performance, energetics and water turnover of tippler pigeons with a harness and dorsal load

We measured carbon dioxide production and water efflux of 12 tippler pigeons (Columba spp.) during seven experimental flights using the doubly labeled water (DLW) method. Prior to the experiment birds were randomly assigned to one of two groups. One group flew as controls (no load or harness) on all seven flights. The other group wore a harness on two flights, a dorsal load/harness package (weighing about 5% of a bird's mass) on two flights, and they were without a load in three flights. Flight duration of pigeons with only a harness and with a dorsal load/harness package was 21 and 26% less, respectively, than the controls. Pigeons wearing a harness, or wearing a dorsal load/harness package lost water 50-90%, and 57-100% faster, respectively, than control pigeons. The mean CO2 production of pigeons wearing a harness or a load/harness package was not significantly different than pigeons without a harness or load. The small sample sizes and large variability in DLW measuremets precluded a good test of the energetic cost of flying with a harness and dorsal load.

Condor↗
USGS1991

Feeding ecology of waterfowl wintering on evaporation ponds in California

We examined the feeding ecology of Northern Pintails (Anas acuta), Northern Shovelers (A. clypeata), and Ruddy Ducks (Oxyura jamaicensis) wintering on drainwater evaporation ponds in California from 1982 through 1984. Pintails primarily consumed midges (Chironomidae) (39.3%) and widegeongrass (Ruppia maritima) nutlets (34.6%). Shovelers and Ruddy Ducks consumed 92.5% and 90.1% animal matter, respectively. Water boatmen (Corixidae) (51.6%), rotifers (Rotatoria) (20.4%), and copepods (Copepoda) (15.2%) were the most important Shoveler foods, and midges (49.7%) and water boatmen (36.0%) were the most important foods of Ruddy Ducks. All three species were opportunistic foragers, shifting their diets seasonally to the most abundant foods given their behavioral and morphological attributes.

Condor↗
USGS1991

Point counts from clustered populations: Lessons from an experiment with Hawaiian crows

We designed an experiment to identify factors contributing most to error in counts of Hawaiian Crow or Alala (Corvus hawaiiensis) groups that are detected aurally. Seven observers failed to detect calling Alala on 197 of 361 3-min point counts on four transects extending from cages with captive Alala. A detection curve describing the relation between frequency of flock detection and distance typified the distribution expected in transect or point counts. Failure to detect calling Alala was affected most by distance, observer, and Alala calling frequency. The number of individual Alala calling was not important in detection rate. Estimates of the number of Alala calling (flock size) were biased and imprecise: average difference between number of Alala calling and number heard was 3.24 (.+-. 0.277). Distance, observer, number of Alala calling, and Alala calling frequency all contributed to errors in estimates of group size (P < 0.0001). Multiple regression suggested that number of Alala calling contributed most to errors. These results suggest that well-designed point counts may be used to estimate the number of Alala flocks but cast doubt on attempts to estimate flock size when individuals are counted aurally.

Condor↗
USGS1991

Growth and development of thermoregulation in nestling San Miguel Island Song Sparrows

Patterns of growth (reviewed by Ricklefs 1968, 1969; O'Connor 1984) and the development of endothermy (reviewed by Dawson and Hudson 1970, Dunn 1975, Hill and Beaver 1982) have been well-studied in altricial wild birds, especially passerines. But few studies compare grown and thermogenesis in separate populations of the same species. Results of such studies with emberizids varied among species. King and Hubbard (1981), for example, found that nestlings from subarctic, subalpine, and low-altitude montane populations of White-crowned Sparrows ( Zonotrichia leucophrys gambelii ) grew at similar rates. In contrast, Rogers (1985) reported that the growth rates of nestlings in different populations of Savannah Sparrows ( Passerculus sandwichensis ) varied in response to the different environmental constraints of the localities in which they were reared. Nice (1937) and Smith et al. (1982) documented patterns of nestling growth in mainland (Ohio) and insular (Mandarte Island, British Columbia, Canada) populations of Song Sparrows ( Melospiza melodia ), respectively, and found that they were similar to those reported for most other passerines by Ricklefs (1968, 1969) and O'Connor (1984). In 1985-1986, we had the opportunity to examine the growth of nestlings from a third race of Song Sparrows, M. m. micronyx , which is endemic to San Miguel Island near Santa Barbara, California. We also studied the development of endothermy in these young birds, a process not hitherto described for nestling Song Sparrows. We report both in this paper.

California↗
USGS1990

Bird specimens and documentation: Critical data for a critical resource

As governments impose increasingly stringent regulations on the collection of bird specimens and as man alters ever greater areas of habitat with the loss of many of their contained species, museum specimens increase immeasurably in importance. Yet at present, museum collections do not contain an adequate representation of the world's avifauna and, unfortunately, are not likely to do so. Thus, it is imperative that data associated with specimens that are obtained be as complete as possible. To this end, we describe categories of information with wide application to many types of studies, outline character states, and recommend standard forms of data notation. We recognize that under certain circumstances, it may be appropriate to record more limited data. However, we encourage at least those engaged in general collecting to record as many of these standard data as possible.

Condor↗
USGS1990

Adaptations to tidal marshes in breeding populations of the swamp sparrow

The Coastal Plain Swamp Sparrow (Melospiza georgiana nigrescens) was originally described from a small number of specimens from the tidal marshes of the Nanticoke River in southeastern Maryland. Based on our quantitative analysis of a larger series of specimens, we found that Swamp Sparrows collected during the breeding season from the Chesapeak and Delaware bays (and tributaries) and near the mouth of the Hudson River are generally less rusty, have more black in the crown and nape, and have larger bills than other Swamp Sparrows. Contrary to earlier accounts, we found M. g. nigrescens to be migratory, arriving after the spring migration and departing before the fall migration of the inland subspecies through the tidal marshes. The location of the wintering groups of M. g. nigrescens is unknown. We argue that the morphological and life history differences characterizing M. g. nigrescens reflect adaptation to tidal marshes. We base this hypothesis on the nature of the morphological differences, which are convergent with other tidal marsh breeding sparrows and other terrestrial vertebrates.

Condor↗
USGS1990

Fat scoring: Sources of variability

Fat scoring is a widely used nondestructive method of assessing total body fat in birds. This method has not been rigorously investigated. We investigated inter- and intraobserver variability in scoring as well as the predictive ability of fat scoring using five species of passerines. Between-observer variation in scoring was variable and great at times. Observers did not consistently score species higher or lower relative to other observers nor did they always score birds with more total body fat higher. We found that within-observer variation was acceptable but was dependent on the species being scored. The precision of fat scoring was species-specific and for most species, fat scores accounted for less than 50% of the variation in true total body fat. Overall, we would describe fat scoring as a fairly precise method of indexing total body fat but with limited reliability among observers.

Condor↗
USGS1989

Foods and dietary strategies of prairie-nesting ruddy ducks and redheads

Actively feeding Ruddy Ducks ( Oxyura jamaicensis ) and Redheads ( Aythya americana ) were collected from North Dakota wetlands during the 1979-1981 breeding seasons. Foods found within esophagi were analyzed on a wet-weight aggregate percent basis. Male and prelaying and laying female Ruddy Ducks consumed >90% invertebrates, primarily chironomids. Postlaying female Ruddy Ducks consumed 73% invertebrates. Male and female (prelaying, laying, and postlaying) Redheads were consistently more omnivorous, consuming 51-70% invertebrates (mostly chironomids) and 30-49% plant matter. Seeds of shallow marsh emergent plants were important in the diet of prelaying and laying female Redheads in 1979, a wet year. Female Redheads used temporally available seed resources in shallow marshes to meet energy requirements for foraging on invertebrates in deeper, more permanent wetlands. Continued losses of easily drained shallow wetlands may represent a serious impediment to our efforts to maintain current Redhead population levels.

The Condor↗
USGS1989

Reproduction and demography of the Florida Everglade (Snail) Kite

An 18-year study of reproduction and survival of the Florida Everglade (Snail) Kite (Rostrhamus sociabilis plumbeus) has revealed the following: extremely poor nesting success (only 13.6% of nests found at the nest-building stage successful); extremely long breeding seasons (some reproductive activity in almost all months in good years); frequent multiple brooding and frequent multiple brooding and frequent renesting after failure; low egg hatchability (81%); high failure rates due to nest collapse, desertion, and predation; extremely high survival of juveniles and adults under good water conditions; and high vulnerability to drought due to near total dependency on a single species of drought-sensitive snail for food. Despite low nesting success, the species has increased rapidly under good conditions, mainly because of multiple nesting attempts within long breeding seasons and high survival rates of free-flying birds. Nesting success varied significantly between regions and nest substrates, but not as a function of seasons or solitary vs. colonial nesting. While nesting success was reduced in low water years, this effect was at least partly due to heavy use of poor nest substrates under such conditions. Clutch size and numbers of young per successful nest varied with regions, but not as a function of seasons or water levels. The effects of coloniality on clutch size and numbers of young were inconsistent. Significant effects of nest-substrate types on clutch size and numbers of young were apparently artifacts of substrate differences between regions.

Condor↗
USGS1989

Regionwide polygyny in willow flycatchers

Most species of North American flycatchers (Tyranidae) are believed to be normally monogamous (Skutch 1960, Verner and Willson 1969). Some instances of bigamy are known for the Eastern Phoebe ( Sayornis phoebe ; Sherman 1952), Eastern Wood-Pewee ( Contopus virens ; W. J. Smith, cited in Eckhardt 1976), Western Wood-Pewee ( C. sordidulus ; Eckhardt 1976), and Acadian Flycatcher ( Empidonax viriscens ; Mumford 1964). Recently, local incidences of polygyny have also been reported for the Least ( E. minimus ; Briskie and Sealy 1987) and Willow ( E. traillii ; Prescott 1986) flycatchers. Here, we present details on two additional instances of polygyny in Willow Flycatchers in different regions of North America, including information on the behavior and nesting ecology of polygynous trios.

The Condor↗
USGS1988

Colony attendance and population monitoring of Black-legged Kittiwakes on the Semidi Islands, Alaska

Patterns of colony attendance in Black-legged Kittiwakes ( Rissa tridactyla ) were studied over 5 years on the Semidi Islands, western Gulf of Alaska. A census period of 50 days, extending from first egg laying through final hatching, was appropriate because counts made then were subject to the least amount of daily variation. Five counts during that period were sufficient to detect a 25% change in numbers between years; counts made on all 50 days of the census period would detect a 5 to 7% change. There was little evidence for seasonal trends or serial correlation of counts during the census period, but attendance was negatively correlated with wind speed. Half of an apparent 17% increase in population between 1980 and 1981 was due to birds spending more time at their nest sites in the latter year, thereby increasing the mean of attendance counts. Despite such difficulties in the interpretation of attendance counts, birds were considered to be better counting units for population monitoring than nests, because nest densities were subject to large annual fluctuations in breeding effort.

Alaska↗
USGS1988

Littoral foraging by red phalaropes during spring in the northern Bering Sea

Phalaropes demonstrate considerable plasticity in their choice of foraging habitats. The Red Phalarope ( Phalaropus fulicaria ) alternates use of pelagic environments in winter and migration (Taning 1933, Stanford 1953, Briggs et al 1984) with wet tundra habitats during the breeding season (Kistchinski 1975, Mayfield 1979, Ridley 1980). Foods available and taken in littoral zones of the Arctic Ocean in fall have been identified (Conners and Risebrough 1978, Johnson and Richardson 1980), but otherwise little attention has been devoted to the transition between the marine and terrestrial periods of the Red Phalarope’s life history. We report phalarope use of littoral areas during spring in the northern Bering Sea and Kongkok Bay, St. Lawrence Island, Alaska. In addition, we describe phalarope foraging tactics and foods available in the sur zone, emphasizing this form of littoral foraging as an opportunistic and facultative feeding strategy.

Alaska↗