William R. Eddleman

Seasonal changes in Yuma clapper rail vocalization rate and habitat use

Yuma clapper rails (Rallus longirostris yumanensis) are protected under the Endangered Species Act, and 90% of the U.S. population occurs within 2 wetland complexes. Assessment of impacts on, and mitigation measures for, Yuma clapper rails are required by law, yet managers lack quantitative information on habitat requirements. Seasonal habitat requirements provide resource managers with the information necessary to assess effects of development and water use practices on Yuma clapper rails in the Southwest. Playback recordings are commonly used to survey rail populations, yet their accuracy has not been evaluated. Consequently, we examined survey techniques and seasonal habitat requirements of Yuma clapper rails during 1985-87 on the lower Colorado River in southwestern Arizona to provide the recovery team and resource managers with reliable population estimates and habitat requirements

Evaluation of lipid indices of the wood thrush

Many techniques for assessing lipid reserves have been used, but techniques are seldom evaluated. We evaluated five common methods (fat scoring, regression residuals of body mass vs. morphological measurements, quotients of body mass divided by morphological measurements, total body electrical conductivity, and water content) for assessing lipid reserves in the Wood Thrush (Hylocichla mustelina) in Rhode Island. Lipid content ranged from 3 to 1 l%, water content ranged from 64 to 72%, and fat score ranged from 0 to 4. Mean total body electrical conductivity (TOBEC) was moderately correlated with lean body mass. Percentage water and fat score were highly correlated with extracted lipid mass and percentage lipid content. Body mass, tail x mass regression residuals, and quotient of body mass/tail length were highly correlated with lean body mass. Morphological measurements were correlated with lean mass only when in association with body mass, but not considered alone. Combining TOBEC readings with body mass and morphological measurements produced regression models with similar predictive abilities as previous studies using TOBEC, but TOBEC provided little or no additional predictive ability. TOBEC did not significantly improve body fat predictive models and does not appear accurate in predicting lipid mass of individual small birds. Fat score and percentage water are useful indices of body fat in Wood Thrush.

California black rail use of habitat in southwestern Arizona

Use of habitat by the California black rail (Laterallus jamaicensis coturniculus) a subspecies threatened in California and endangered in Arizona, is not sufficiently well known for effective management. From March 1987 to December 1988, we studied use of habitat by 36 radio-transmittered California black rails at Mittry Lake Wildlife Management Area, Arizona. Birds selected (P 6 cm deep. Birds used areas that were closer to vegetation-type edges, were drier, and had shorter vegetation compared with available habitat (P < 0.001). Habitat structure was more effective than plant composition in predicting California black rail use of habitat. Because California black rails may not use areas within wetlands where deep water occurs, we recommend that fluctuations in water level be minimized in wetlands managed for California black rails, especially during the nesting season. Assessment of California black rail habitat should include not only vegetational cover, but also water depths within wetlands, access to upland vegetation, and overhead coverage by emergent vegetation

Seasonal changes in fatty acid composition of the wood thrush

Lipid storage is important for avian reproduction (Drobney 1980, Krapu 1981, Walsberg 1983), migration (Blem 1980, Biebach et al. 1986), and survival (Lima 1986, Blem 1990; but see Krementz et al. 1989). In addition to total lipid content, lipid composition is important because the melting points of fatty acids differ, thereby influencing ease of mobilization, use at low temperatures, and net energy produced (Blem 1990). Indeed, lipid composition is essential to an accurate evaluation ofavian bioenergetics (Johnston 1970). Lipid composition is particularly important for long-distance migratory birds because small migrants increase reliance on fatty acids during migration (Marsh 1981) and individuals that store fats that have higher energy and are more easily mobilized will be able to travel farther between stopovers during their long migration (Johnston 1970, Yom-Tov and Tietz 1978). Food sources high in unsaturated, high-energy fats may be important to birds preparing for autumn migration. After the onset of migration, individuals with larger lipid stores and storing lipids high in easily mobilized fats should be better able to survive unpredictable weather and food availability encountered during migration. Clearly, we need to examine the types of lipids important for migrating birds and identify the food items which supply migratory birds with essential fatty acids. Lipid composition and the factors affecting it have been evaluated infrequently in birds. Examination of seasonal changes in lipid composition and identification of important food sources high in essential fatty acids is an important component for improving our understanding of the ecology and evolution of migration in birds. Consequently, we examined lipid composition of breeding and autumn-migrating Wood Thrush. We also examined lipid composition of spicebush (Lindera benzoin) fruits and seeds because they are commonly eaten by Wood Thrush preparing for autumn migration.

HOME RANGE SIZE, NEST-SITE SELECTION AND NESTING SUCCESS OF BLACK RAILS IN FLORIDA

Abstract We radio-tagged Black Rails (Laterallus jamaicensis) and located active nests at two sites in Florida from May 1992 to August 1996. We collected telemetry locations from 1–6 h daily during the egg-laying and incubation period. Home range estimates differed significantly between sexes; males used 1.3 ha and females used 0.62 ha. Nests were found at all stages of egg-laying and incubation using radio telemetry and visual nest searching. Nests were located during each month from May through August. Nests were constructed over moist soil in low (≤1 m) dense herbaceous vegetation. Black Rails preferred nest sites near hyper-saline patches of bare sand. The Mayfield estimate of nesting success was 43%, nest failures were caused by flooding and predation. Imported red fire ants (Solenopsis invicta) were observed constructing mounds under three nests and killed one hatchling before it emerged from the egg. Water level and hydrology may have the greatest impact on nest-site selection and nesting success of Black Rails.

Effects of disturbance on activity and energy budgets of migrating waterbirds in south-central Oklahoma

We studied effects of disturbance on migrating waterbirds during spring on Cumberland Pool at Tishomingo National Wildlife Refuge, Tishomingo, Oklahoma, USA, 1999 and 2000. We recorded 240 disturbances in 477.5 hr of observation of American coots (Fulica americana), American white pelicans (Pelecanus erythrarhynchos), black terns (Chlidonias niger), blue-winged teal (Anas discors), and Franklins gulls (Larus pipixcan). Recreation (n = 208) accounted for 86.7% of all disturbances, natural disturbances (n = 23) accounted for 9.6%, and 3.3% of disturbances (n = 8) were unknown. Boat fishing increased alertness by American white pelicans but did not affect escape behavior. Recreational disturbances caused increases in escape activities and alertness of American coots. However, only boat fishing increased energy expenditure by American coots. Rates of disturbance differed between species and appeared to be correlated to foraging strategies, habitat requirements, and type of disturbance. Therefore, managers of public lands should consider habits and migration chronologies of waterbirds when setting seasonal recreation dates. Modifying recreation policy could reduce rates of disturbance to some waterbirds. Future research should be aimed at constructing energy budgets and measuring body condition of birds at multiple staging areas during spring to determine whether recreational disturbance ultimately affects reproductive success.

Effectiveness of AV-1011® to Reduce Damage to Drill-Planted Rice from Blackbirds

ABSTRACT We determined efficacy of AV-1011® (a 50% anthraquinone product; Arkion® Life Sciences, New Castle, Delaware) on drill-planted rice seed to reduce blackbird damage and determine residue levels of anthraquinone (AQ) in rice seeds and seedlings and in the mature rice crop under field enclosures at the University of Missouri-Delta Center farm near Portageville, Missouri. Red-winged blackbird (Agelaius phoeniceus) damage was higher for untreated than AV-1011® treated rice seedlings at assessment period 3, 15 days postplanting (F 1,141 = 15.81, P < 0.001), and at assessment period 4, 19 days postplanting F 1,136 = 11.54, P = 0.001). Blackbird damage to AV-1011-treated seedling for assessment periods 3 and 4 was 8% and 7%, respectively, while blackbird damage to untreated seedlings during the same assessment periods was 52% and 44%. More blackbirds used untreated plots than AV-1011-treated plots during assessment periods 2–4 (F 1,17.8 = 20.02, P < 0.001). Overall concentrations of AQ on seeds averaged 5,993 µg/g or 0.59% during the test period. Concentrations of AQ in mature rice seed and plant collected at harvest averaged 1.22 µg/g and 0.10 µg/g, respectively. AV-1011 offers promise for reducing bird depredations to newly planted rice, but additional testing should be conducted to evaluate this repellent in a large-scale field setting.

Chronology of migration by American coots in Oklahoma

American coots (Fulica americana) were studied on large reservoirs in north-central Oklahoma in 1979-82 to determine chronologies of migrations by ageand sex class. Coots began migrating into Oklahoma in mid-September, numbers peaked in early to mid-October, and few birds were seen after 1 November. Some late migrants appeared in mid-December. In spring, coots began migrating in late February, numbers peaked in mid-April, and the last birds were seen in mid-May. Generally, adult and juvenile males and juvenile female coots migrated simultaneously in autumn, but adult females completed migration by 1 November. A few juveniles and adult males migrated in December. Adult coots preceded yearlings in spring. Despite annual and between-lake differences in chronology of autumn migration, most coots migrated before waterfowl hunting seasons in Oklahoma. Coot hunting seasons in mid-latitude states should commence before the general waterfowl season where management goals are to increase hunter interest and the harvest of birds. J. WILDL. MANAGE. 49(1):241-246 Information on the chronology of movements by migratory game birds is essential to regulating harvest (Crissey 1965). Changes in regulations have provided hunters with greater harvest opportunities for waterfowl species migrating earlier than others (Martinson et al. 1966) or species not as vulnerable to shooting pressure (Crissey 1965). The chronology of migration of American coots has received little attention relative to harvest regulations and migration of different ageand sex classes, presumably because hunters have little interest in harvesting coots (Fredrickson et al. 1977:143, Gorenzel 1979:69). Nevertheless, annual harvest of coots averaged 1.17 million birds for 1964-76 (Martin 1979:33), and biologists believe the harvest can be increased (Fredrickson et al. 1977:138). Specific data on general and age-specific chronology of migration by coots are therefore necessary to determine potential changes in regulations to allow increased harvest of coots, the effects of such changes on different segments of coot populations, and the timing of habitat manipulations to attract migrating coots (Fredrickson and Taylor 1982). We determined chronology by age and sex of coots during autumn and spring migrations in Oklahoma to determine the overlap between coot migration chronology and waterfowl season dates and to elucidate patterns of differential migration by age and sex. We thank S. A. Martin, D. Martin, T. C. Tacha, M. E. Heitmeyer, D. P. Hector, D. Latham, P. Harjo, and others for field and laboratory assistance. Personnel of the Okla. Dep. of Wildl. Conserv. provided valuable logistical assistance. We also thank M. W. Weller, L. H. Fredrickson, W. P. Gorenzel, M. E. Heitmeyer, J. W. Lish, F. Schitoskey, and L. G. Talent for helpful comments on the manuscript. E. Waugh and D. Savage granted permission to use Sooner Lake and Lake Carl Blackwell as study areas, respectively. W. D. Warde provided statistical advice. This study was funded by the Accelerated Res. Program for Migratory Shore and Upland Game Birds, U.S. Fish and Wildl. Serv. Contract #14-16-0009-79-085; Oklahoma State Univ.; and the Oklahoma State Univ. Mus. of Nat. and Cult. Hist. The Okla. Coop. Wildl. Res. Unit is supported by the Okla. Dep. of Wildl. Conserv., Oklahoma State Univ., the U.S. Fish and Wildl. Serv., and The Wildl. Manage. Inst.