Carl E. Korschgen

Breeding Stress of Female Eiders in Maine

Physiological condition of breeding female American eiders (Somateria mollissima dresseri) was studied on islands in Penobscot Bay, Maine, from 1973 to 1975. Of particular interest was the hypothesis that stresses associated with reproduction predispose eiders to increased mortality and lowered productivity. Females established large nutrient reservws prior to egg laying and essentially terminated feeding before laying. They relied heavily on nutrient reserves for formation of eggs. Wet weights of the gizzard, liver, and intestine decreased significantly during follicular development before and during laying. There was no correlation between body weight and clutch size after egg laying, suggest:ng that clutch size was determined by size of nutrient reserves. Females fed little or not at all during incubation and lost 32 percent of their post-laying weight. Wet weights of the pectoral muscle decreased significantly. Based on fat and protein levels, most females probably could not continue to incubate when body weights approached 1.10 kg. Hematocrit percentages and levels of total plasma protein and free fatty acids were physiological parameters that indicated degenerative changes in incubating eiders. Levels of non-protein nitrogen in the blood plasma appeared to be considerably depressed but did not change during incubation. The renesting ability of American eiders appeared limited, at least in part, by the dysfunction of the digestive tract concomitant with egg laying. The digestive tract was so altered that even when a clutch was lost after only a few days of incubation, females required many days to reestablish

Implanting intra-abdominal radiotransmitters with external whip antennas in ducks

We developed and evaluated a surgical procedure for implanting intra-abdominal radiotransmitters with external whip antennas in captive mallards (Anas platyrhynchos). Transmitters were implanted in the abdominal cavity and the antennas exited through the caudal abdominal wall and skin. Birds with implanted transmitters developed mild to moderate localized air sac reactions. These reactions involved adhesions of the right anterior abdominal air sac to the liver with contractions around the transmitters and antenna catheters. The adhesions were reinforced by a proliferation of connective tissue and lined by multi-nucleated giant cells (foreign body reaction). Casual observation indicated that neither behavior nor activity of the birds was altered by the histological reaction to the transmitter implant. No increase in systemic lesions (particularly liver or kidney) could be correlated with the histological reactions. Our evaluations indicate that the procedure is a reliable method for radiomarking ducks and the technique has been successfully used in 2 field studies.

Survival of Radiomarked Canvasback Ducklings in Northwestern Minnesota

Duckling survival, an important factor affecting annual recruitment, has not been determined adequately for canvasbacks (Aythya valisineria). We investigated the magnitude, timing, and causes of mortality of canvasback ducklings from hatch to fledging at the Agassiz National Wildlife Refuge (NWR) in northwestern Minnesota during 1987-90. During the 4 years, 217 day-old ducklings were radiomarked and released in 52 broods. Another 141 ducklings were radiomarked at ≥ 4 weeks of age. Survival was estimated with the Kaplan-Meier nonparametric estimator and the Weibull parametric model. Most mortalities occurred within 10 days after hatch. Total brood loss occurred in 18 (35%) of 52 broods released. The primary sources of mortality were predation, principally by mink (Mustela vison), and exposure to precipitation and cold temperature. For combined years, females had lower survival than males (P = 0.03). If the disparate survival between sexes of canvasbacks observed in this study is representative of canvasbacks in their breeding range, this phenomenon contributes to reduced reproductive potential and the male-biased sex ratio of the species.

Evaluation of implanted radio transmitters in ducks

Avantages de la methode et amelioration a y apporter (elle est testee sur Anas platyrhynchos, Aythya americana, Bucephala clangula et Ay. collaris)

Effects of irradiance on growth and winter bud production by Vallisneria americana and consequences to its abundance and distribution

Abstract Number, total biomass, and individual mass of winter buds of Vallisneria americana was significantly related to the depth of the 1% of surface irradiance (Z) and the photosynthetic photon irradiance calculated for each shading treatment imposed during this study. Between the range of 23.8 and 111.2 cm depth for the 1% Z, total biomass of winterbuds produced ranged from 0.63 to 0.01 g, counts ranged from 3.5 to 0.1, and mass of individual winterbuds ranged from 0.18 to 0.04 g. Total biomass of winter buds produced was reduced when plants were exposed to a 14-day period without irradiance during the middle of the growing season. Applying the results of the culture experiments to conditions found in Navigation Pool 8 of the Upper Mississippi River suggests that irradiance may indeed limit the distribution and abundance of Vallisneria americana by reducing the number and size of winter buds.

SCIENCE FOR AVIAN CONSERVATION: PRIORITIES FOR THE NEW MILLENNIUM

activities have become the preeminent natural resource conservation effort in North America. Maturation of the North American Waterfowl Management Plan (NAWMP), establishment of Partners in Flight (PIF), and creation of comprehensive colonial waterbird and shorebird conservation plans have stimulated unprecedented interest in, and funding for, bird conservation in the United States, Canada, Mexico, and other countries in the western hemisphere. Key to that success in the United States has been active collaboration among federal, state and local governments, conservation organizations, academia, and industry. The U.S. Department of the Interior (DOI), which has primary statutory responsibility for migratory bird conservation and management, has been a key partner. Despite the great strides that have been made in bird conservation science, historical approaches to research and monitoring have often failed to provide suffi cient information and understanding to effectively manage bird populations at large spatial scales. That shortcoming, and the lack of an integrated strategy and comprehensive set of research priorities, is more evident in light of the goals established by the North American Bird Conservation Initiative (NABCI). The NABCI is a trinational, coalitiondriven effort to provide an organizational umbrella for existing conservation initiatives. The expanded focus of NABCI and individual bird conservation initiatives is to work together in an integrated, holistic fashion to keep common birds common and to increase populations of declining, threatened, and endangered species. To assist bird conservation initiatives in defi ning goals and developing new approaches to effective research, the U.S. Geological Survey (USGS), the research agency of DOI, convened a workshop, “Science for Avian Conservation: Understanding, Modeling, and Applying Ecological Relationships,” on 31 October–2 November 2000, which brought together 51 scientists from USGS, as well as scientists and conservationists from other agencies and organizations actively participating in NABCI. As 1 U.S. Geological Survey, Midcontinent Ecological Science Center, 4512 McMurry Avenue, Fort Collins, Colorado 80525-3400, USA; 2 U.S. Geological Survey, 12201 Sunrise Valley Drive, Reston, Virginia 20192, USA; 3 U.S. Geological Survey, Patuxent Wildlife Research Center, 11510 American Holly Drive, Laurel, Maryland 20708-4017, USA; 4 U.S. Geological Survey, National Wildlife Health Center, 6006 Schroeder Road, Madison, Wisconsin 53711, USA; 5 U S. Fish and Wildlife Service, 7920 Northwest 71st Street, Gainesville, Flordia 32653, USA; 6 U.S. Geological Survey, Center for Biological Informatics, Building 810 DFC, MS 302, Denver, Colorado 80225; 7 U.S. Geological Survey, Upper Midwest Environmental Science Center, 2630 Fanta Reed Road, La Crosse, Wisconsin 54601, USA; and 8 U.S. Geological Survey, Water Resources Division, P.O. Box 25046, Lakewood, Colorado 80225, USA JANET M. RUTH,1,9 DANIEL R. PETIT,2,10 JOHN R. SAUER,3 MICHAEL D. SAMUEL,4 FRED A. JOHNSON,5 MARK D. FORNWALL,6 CARL E. KORSCHGEN,7,11 AND JAMES P. BENNETT8 SCIENCE FOR AVIAN CONSERVATION: PRIORITIES FOR THE NEW MILLENNIUM The Auk 120(1):204–211, 2003

Thermoregulatory effects of radiotelemetry transmitters on mallard ducklings

Many telemetry transmitter attachments disrupt downy insulation, and may bias survival studies during cold weather by making ducklings more susceptible to chilling. We compared thermal responses of untreated 1-day-old mallards (Anas platyrhynchos) to ducklings carrying external sutured backpack or subcutaneously implanted transmitters. Ducklings carrying external transmitters showed areas of increased surface temperature in thermographic images. However, open-circuit respirometry studies at 5, 10, 15, 20, and 25 C and wind speeds of 0.1, 0.2, 0.5, and 1 m/s indicated no biologically significant differences in total heat production, net heat production, or short-term body mass loss. These results do not exclude the possibility of other negative effects of transmitters on duckling behavior and survival.

The occurrence of mycoplasmas in selected wild North American waterfowl

We determined the prevalence of mycoplasma infection in breeding mallard (Anas platyrhynchos) and canvasback (Aythya valisineria) hens and their broods from the central United States (1988 to 1990); and wintering American black duck (Anas rubripes) and mallard hens from the eastern United States (1990 to 1993). Mycoplasmas were isolated by culturing tracheal swabs from 656 live birds and tissue samples from 112 dead waterfowl. Nine (18%) of 51 mycoplasma isolates were identified as Mycoplasma anatis; M. anatis was recovered from four mallards, a black duck, and a gadwall (Anas strepera) duckling. Nineteen (37%) of 51 mycoplasma isolates were identified as Mycoplasma cloacale; these isolates were obtained from mallard, canvasback, and black duck adults, and from a mallard duckling. Additional unspeciated mycoplasmas were isolated from mallards, black ducks, and one canvasback.

A Voluntary Program to Curtail Boat Disturbance to Waterfowl During Migration

Abstract A voluntary waterfowl avoidance area (VWAA) was established on Lake Onalaska in Navigation Pool 7 of the Upper Mississippi River, Wisconsin, USA, in 1986, to reduce boating disturbance to migratory waterfowl. We monitored boater compliance with the VWAA program in 1993 and 1997. Of 1,664 “boating events” observed on Lake Onalaska, boats intruded into the VWAA on 127 occasions. Boating events have increased from 1.82 boating events/h in 1986-88 to 1.97 in 1993 and 2.58 in 1997. Despite a 60% increase in boating traffic, the lake-wide disturbance rates in 1997 were comparable to that in 1981. We attribute this to a significant reduction in the proportion of lake-wide boating events that resulted in disturbance, a direct consequence of the VWAA program. Rate of intrusion into the VWAA was 0.11 per boating event in 1997 compared to 0.18 per boating event in 1986-88. Boating disturbances to waterfowl within the VWAA occurred at about half the rate (0.24 to 0.28 disturbances·hr-1) observed prior to establishment of the program (0.48 disturbances·hr-1). We also identified access points used by boaters and boating activities that were most likely to result in intrusion into the VWAA and associated disturbance to waterfowl. Results of these analyses have provided useful information to resource managers for targeting public education efforts. The VWAA program has contributed to the value of Lake Onalaska as a waterfowl refuge and demonstrates an effective collaboration among government agencies and non-governmental organizations.

Metabolic Response to Air Temperature and Wind in Day‐Old Mallards and a Standard Operative Temperature Scale

Most duckling mortality occurs during the week following hatching and is often associated with cold, windy, wet weather and scattering of the brood. We estimated the thermoregulatory demands imposed by cold, windy weather on isolated 1‐d‐old mallard (Anas platyrhynchos) ducklings resting in cover. We measured O2 consumption and evaporative water loss at air temperatures from 5° to 25°C and wind speeds of 0.1, 0.2, 0.5, and 1.0 m/s. Metabolic heat production increased as wind increased or temperature decreased but was less sensitive to wind than that of either adult passerines or small mammals. Evaporative heat loss ranged from 5% to 17% of heat production. Evaporative heat loss and the ratio of evaporative heat loss to metabolic heat production was significantly lower in rest phase. These data were used to define a standard operative temperature (Tes) scale for night or heavy overcast conditions. An increase of wind speed from 0.1 to 1 m/s decreased Tes by 3°–5°C.