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The objective of this study was to understand the pattern of variation in group structure and feeding behaviour of wintering Common Goldeneyes ( Bucephala clangula) on the Saint-Lawrence River, by comparing two major habitats for this species in the province of Quebec, one in freshwater and one in saltwater. Groups of goldeneyes were smaller in Montreal than in the estuary and consisted of twice as many males. Individuals spent a greater proportion of time feeding in Montreal than in the estuary. At Montreal, goldeneyes spent more time feeding under water. Temporal variables had a major influence on group structure and on diving time. At Montreal, time of day explained most of variation whereas in the estuary, tide was more important.

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.

In the autumn 2013 were set up 50 nest boxes for increasing of density of the Common Goldeneye population (Bucephala clangula) in Třeboň region. The main objectives of this study were to check the nest boxes after breeding season and analyse the results. These nest boxes were checked in the July 2014 and 2015. In the spring 2015 were set up 2 mobile scouting cameras to the selected nest boxes. There was also monitor the occurrence of the Common Goldeney on the Naděje fishpond system and Prátr fishpond system by counting. The Naděje fishpond system is created by 16 different sized fishponds and it is situated approximately 8.5 km to the south of the town Veselí nad Lužnicí. The Prátr fishpond system is situated approximately 1 km to the south of the town Třeboň and it is created by 9 fishponds. The monitor was realised in term from 17. 3. 2015 to 27. 7. 2015. The other species of water birds were also counted. In the year 2014 10 nest boxes were occupied and in the year 2015 17 nest boxes were occupied. The nest boxes which were located on the fishpond´s islands were preferred. Both of the mobile scouting cameras recorded European Pine Marten (Martes martes) devastating the nest. The Common Goldeneye was occurred on the both fishpond systems in 2015. In the year 2015 was observed the female of the Common Goldeneye with 8 ducklings on the Prátr fishpond system.

Military jet over-flight activities pose a potential threat to staging waterfowl and pilots. The migration period is important for nutrient acquisition and courtship as these waterfowl enter the breeding season. Using a focal animal (continuous) technique for five-minute intervals, diurnal Time/Activity (TA) budgets for Canada Geese (Branta canadensis canadensis) (n=751), American Black Duck (Anas rubripes) (n=474) and Common Goldeneye (Bucephala clangula) (n=1274) were compiled during 216 hours of behavioural observation. The study was conducted from 26 April to 27 May, 2002 at the outlet of Lac Fourmont, Labrador (52° 03' 30"N, 60° 31' 01" W), in an ashkui or area of open water in an otherwise frozen landscape, which is known historically as a place to hunt waterfowl. These staging grounds are within the 130 000 km2 Low-level Training Area (LLTA) of the Quebec-Labrador Peninsula. Generalized Linear Modeling (GLM) of ranked variables was used to analyze behaviour by: observer, sex, pair status, time of day, date, and each weather parameter. Male Common Goldeneye spent more time in courtship behaviours (2.7%) than females (1.1%) and they spent most of the daylight hours feeding (males 53.3% and females 54.5%), with little time resting (4.8% and 5.2%, respectively). In contrast, Black Ducks and Canada Geese spent relatively little time feeding (12.4% and 5% respectively) and most of their time sleeping (35% and 38% respectively) and locomotion (37.8% and 11% respectively). Ashkui are important to Common Goldeneyes for foraging, and to Canada Geese and Black Ducks for resting prior to the breeding season. / Ninety-one low-level jet over-flights occurred and sound levels (n=336 h) at the study site were measured. Effects of low-level jet over-flights were analyzed using GLM of ranked variables in order to analyze a number of variables simultaneously. All behavioural observations that occurred in the quarter hour periods up to 165 minutes after an over-flight were analyzed. Alert and courtship behaviours of Canada Geese increased after over-flights. Other behaviours were negatively affected to a lesser degree. Locomotor activities by Black Ducks increased significantly immediately following over-flights with a stronger movement response with increased noise. Increases in agonistic and comfort behaviours of Common Goldeneye were detected following over-flights with few other significant affects on their behaviour. / Key words. Anas rubripes, Branta canadensis, Bucephala clangula, disturbance, jet aircraft, Labrador, low-level flying, military activity, noise, spring staging, time-activity budgets, waterfowl

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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...