Intraspecific nest parasitism was studied in a group of colonial Red-breasted Mergansers (Mergus serrator) nesting on the Tern Islands of Kouchibouguac National Park in New Brunswick in 1992. Nest parasitism is very common in this colony, and may influence the high rate of nest abandonment observed. Emphasis was placed on determining rates of successful parasitism (i.e. eggs added during the laying period of the hen at that nest), which are evolutionarily significant, and can easily go undetected. Three methods were used to determine if a nest contained egg(s) from another hen: abnormally large clutch size: more than one egg laid per day: and comparisons of DNA fingerprints of the hen versus putative chicks. When eggs were added to a nest during incubation, the nest was also labelled parasitized, but such eggs were not fully incubated (non-term) and thus were not successful. A new method of blood sampling ducklings in pipped eggs was tested and found to have negative effects on survival. As many as 14.8% (13/88) of the ducklings sampled subsequently died. Researchers wishing to use this method should proceed with caution. DNA fingerprinting determined that 50.0% of nests tested (6/12) were successfully parasitized. Two of six parasitized nests would have gone undetected using the other criteria to detect parasitism, thus proving the value of DNA fingerprinting. Of hatched young genetically analyzed, 30.9% (17/55) were parasitic. Nest parasitism appears to be an alternative breeding strategy in this population. Extra-pair copulation, previously unrecorded in this species, was discovered through DNA fingerprinting in two of four nests analyzed.

The rate of intraspecific nest parasitism was determined for a colony of Red-breasted Mergansers (Mergus serrator) nesting on the Tern Islands in Kouchibouguac National Park, New Brunswick. In order to recognize instances of nest parasitism, field criteria and microsatellite analysis testing for parentage between attending hens and the eggs in their nests were used. Traditionally, molecular analysis has involved collecting blood samples from females and offspring, however, for the purpose of this study, DNA was extracted successfully from feathers, egg membranes, and unhatched embryos which were collected during the summers of 1999 and 2000. A total of 8 primer pairs which amplified microsatellite loci in closely related avian species were tested (Sfimu-2, Sfimu-3, Sfimu-4, Sfimu-5, Sfimu-6, Sfimu-7, Bcamu-6, and Alamu-1). Four of these primers produced product of the expected size (Sfimu-3, Sfimu-4, Sfimu-7, and Bcamu-6). Amplification of these loci, however was inconsistent and subsequent sequence analysis revealed that the amplicons did not contain tandem repeats and therefore were not useful in genotyping. From field criteria we were able to establish rates of parasitism of 46% and 44% for each season. Rates of parasitism tended to be higher at the beginning of the season, compared to nests initiated later. Field criteria bring support to several hypotheses on causes of nest parasitism, indicating that more than one may influence rates of parasitism in a population.

No description available.

No description available.

Clearing of old growth forests resulted in a substantial loss of nesting habitat for cavity-nesting waterfowl during the late 19th and early 20th centuries. Since then, many hardwood forests have matured into size classes capable of producing cavities suitable for nesting ducks. To quantify changes in cavity availability in U. S. Fish and Wildlife Service Region 3, which contains most of the midwestern U.S., I examined current cavity availability at 4 sites where cavity availability had been estimated in the past; Mingo National Wildlife Refuge (NWR) in Missouri, Shiawassee NWR in Michigan, Mead Wildlife Area (WA) in Wisconsin, and Muscatatuck NWR in Indiana. I found densities of 1.8 ± 0.4, 1.4 ± 0.3, 0.9 ± 0.4, and 1.8 ± 0.4 suitable cavities per hectare at each of these sites, respectively. Suitable cavities per hectare increased at Mingo NWR (433%) since 1966 and Shiawassee NWR (1400%) since 1974, but remained similar at Mead WA and Muscatatuck NWR since the mid-1980's, after accounting for differences in past, study-specific criteria for cavity suitability. Differences among sites were likely due to variation in species composition, stage of forest maturation, timber management, and time elapsed since the previous studies. Comparison of size-class distributions for all trees and for trees with cavities indicated that cavities occur in the largest trees and that forests have yet to mature into the most prolific cavity-producing size classes. This conclusion was corroborated by forest growth modeling results from Forest Vegetation Simulator, a forest growth-modeling program from the USDA Forest Service. I used Forest Inventory and Analysis data to model growth from 2008 to 2058 at 10-year intervals for Region 3. Cavity per tree estimates from the 4 study sites were applied to modeling outputs, and cavity availability was projected to almost double over the entire region by 2058. Thus, the observed and further expected increases in cavity density in the region justify re-examination of nest box programs and possibly a reduction of artificial nest boxes in some areas of the region where sufficient natural cavities exist. Because current and future estimates indicate sufficient nest sites for cavity-nesting waterfowl, efforts should be spent protecting and restoring brood-rearing wetlands, which are known to be declining in many areas of Region 3.

Man-made nest boxes are surrogate nest sites widely used by waterfowl managers in North America to propagate free-ranging Wood Ducks (Aix sponsa) and other cavity-nesting waterfowl. I monitored 129 and 174 nest boxes in 2020 and 2021, respectively, at Noxubee National Wildlife Refuge and York Woods, Mississippi. I evaluated site-specific biotic and abiotic factors that were potentially influential on nest survival of Wood Ducks and general nesting ecology and apparent nest success of Black-bellied Whistling Ducks (Dendrocygna autumnalis) and Hooded Mergansers (Lophodytes cucullatus). Daily survival rate of Wood Ducks was negatively influenced by increasing encroaching vegetation at Noxubee NWR and varied by year at York Woods. Across both sites and years, Black-bellied Whistling Duck and Hooded Merganser nest success averaged 59% and 77%, respectively. I also evaluated eggshell breaking strength (EBS) between all three species, where EBS was highest in Hooded Mergansers, followed by Black-bellied Whistling Ducks and Wood Ducks.

Piscivorous birds are often blamed for causing significant damage to fish stocks. Various methods are used to determine the composition of their food, each of them has limits in its ability to determine the complete food spectrum. This work maps the complete food composition of 14 species of fish-eating birds with a method that is not commonly used. Method used in this work uses analysis of publicly available photos on Google.com. In addition to the complete composition of the food, the species composition of the non-fish part of the prey was also determined, and in the case of the Great Cormorant (Phalacrocorax carbo), also the length of the fishes it catches. The aim of this work is to reveal the usability of this method for these purposes. A total of 2350 retrieved photographs were analyzed. The results obtained by photo analysis are in all cases compared with data in the available literature. For representatives of heron birds (Ardeidae), the analysis of photographs provided good information on the food spectrum of individual birds and on the qualitative composition of the non-fish component. It also provided relatively good information on the diet of the White-tailed Eagle (Haliaeetus albicilla), but the bird part of the prey was slightly underestimated. In the diet of the Great Crested Grebe...

The seasonal and diel feeding habits of the goosander, Mergus merganser, the red-breasted merganser, M. serrator, gulls (Larus canus, L. argentatus and L. fuscusj and terns, Sterna hirundo/paradisaea were studied at 64V05'N. Birds' activity patterns were influenced by the nocturnal spawning of the river lamprey (Lampetra fluviatilis). Food selection and food consumption by hand-raised mergansers together with aquarium studies of the diel activity patterns of their most important prey supplemented the field data. River lamprey dominated the diet of the goosander by weight and the sculpin Cottus gobio by number. The fish consumption of the goosanders was found to be about 12% of the available river lamprey biomass and about 17% of the sculpin biomass during the breeding season. In experimental situations the river lamprey was a low- pritority species compared with salmon , Salmo salar, brown trout, 53. trutta, and minnow, Phoxinus phoxinus, when presented to satiated birds of both Mergus species. When hungry, however, the birds caught the available prey irrespective of species, but they selected larger prey when two size classes were present. Experimental results were compared with field data on availability, consumption and the escape behaviour of the various fish species. The rivers emptying in the Bothnian Bay are regarded as important feeding areas for birds breeding along the coast. In early spring they get access to abundant and reliable food resources, e.g the river lamprey. Later on the three-spined stickleback, Gasterosteus aculeatus, supply both Mergus species with food in the river and also along the coast. From the middle of June potential food supply available to birds decreases in the rivers and becomes more abundant in the coastal area. / <p>S. 1-41: sammanfattning, s. 43-227: 7 uppsatser</p> / digitalisering@umu

5 Abstract This thesis is aimed at spatial variability of population structure of our four most common and the most numerous species of ducks wintering in the Czech Republic. These analysed species are Mallard (Anas platyrhynchos), Tufted duck (Aythya fuligula), Common Merganser (Mergus merganser) and Northern Goldeneye (Bucephala clangula). The field data were collected by January International Waterbird Census in the Czech Republic between 2004 and 2013. Analysed habitat variables include: type of wetland, altitude, population size, level of urbanisation (size of settlement) and mean January air temperature in the investigated site. There was found no significant effect of type of wetland and local population density on population structure in any of these bird species. The next factor, altitude of sites was confirmed as significant only for Mallards, when increasing altitude decreased proportion of males in the population. Furthermore, effect of urbanization was found also in Mallard, when proportions of males increased with level of urbanization, i.e. in larger cities. Finally, , temperature of sites was confirmed to be significant factor affecting population size in the three analyzed species, i.e. in Mallard, Tufted Duck and Northern Goldeneye. Except Common Merganser, ratio of males grew with...