Environmental conditions on wintering or spring-staging areas may influence subsequent reproductive performance in migratory birds. These cross-seasonal effects may result from habitat loss and degradation (e.g., via contamination) which in turn reduce reproductive success, particularly in waterfowl that use stored nutrients for reproduction. North American lesser scaup (<i>Aythya affinis</i>) and white-winger scoter (<i>Melanitta fusca</i>) numbers have declined over the past 20 years, particularly in the boreal forest, and remain well below conservation goals, whereas ring-necked duck (<i>A. collaris</i>) numbers have increased. Environmental changes on scaup and scoter wintering and staging areas have raised concern about possible cross-seasonal effects on birds arriving on breeding grounds. The spring condition hypothesis (SCH) purports that many female scaup fail to acquire sufficient nutrients in late winter and spring, causing a decrease in breeding propensity and productivity. The contaminant hypothesis proposes that increased exposure to contaminants (particularly selenium [Se]) on wintering and staging areas has decreased scaup productivity. Accordingly, I compared body condition and studied Se concentrations in scaup, scoters and ringnecks to test the condition and contaminant hypotheses. <p>Scaup had similar body condition to ringnecks, and had similar body mass compared to scaup collected near Yellowknife, NT, in 1968-70. There was no relationship between scaup and ringneck nutrient levels and claw tip carbon, nitrogen or hydrogen isotope values, suggesting that arrival body condition likely was not related to location or diet several months prior. Instead, scaup and ringnecks nutrient levels may be more affected by feeding or habitat conditions on or near the breeding grounds. Scaup had slightly higher liver Se concentrations than ringnecks, but levels in both species were below recognized harmful threshold concentrations; I found no relationship between Se and breeding propensity, or between Se and somatic lipid or protein stores. Scoters had much higher Se concentrations, yet contrary to predictions, there were positive relationships between Se and both lipid stores and breeding status. Follicle [Se] in scaup was below threshold concentrations; despite high liver Se in scoters, egg and follicle levels also were well below threshold concentrations. Using both body composition analysis and stable-isotope analysis I determined that scoters derive egg protein from their breeding ground diet, which likely prevents Se deposition from somatic protein to eggs, and egg lipids are apparently derived from somatic tissues. In all three species, liver Se concentrations were significantly correlated with claw tip ä15N. As the claw tip likely represents assimilated diet from 2-5 months prior to sampling, this correlation suggests that Se in these boreal breeding species is carried over from wintering and staging areas. <p>Overall, results did not support either the spring condition or contaminant hypotheses. Scaup and scoters are late-nesting species, with highest pair densities occurring at the northern extent of their range. Maximum ring-neck pair densities occur at more southern latitudes. Ring-necks also nest earlier and appear to be more flexible in timing of nest initiation. Therefore, it is possible that due to climate change, early spring conditions alter the optimal timing of nest initiation to the detriment of late-nesting species such as scaup and scoters, and favour earlier nesters like ringnecks. Further research into this mismatch hypothesis is warranted.

Nesting success is an important vital rate affecting the reproductive fitness of birds, and predation typically is the single most important factor affecting nesting success. Presumably, birds should nest in locations that maximize nest survival. If specific nest characteristics increase the probability that a nest will hatch, natural (phenotypic) selection could favour use of sites with these features, producing nonrandom patterns of nest site use. Alternatively, birds that are highly selective in nest site choices might be at a disadvantage if predators learn to forage preferentially in these locations and improve their efficiency in depredating nests; in this case, random nesting patterns could be favoured. Finally, it has been hypothesized that predation pressure can influence nest site selection patterns of entire bird communities. If predators develop a search image to hunt for bird nests, then nests that are most similar to each other, irrespective of species, should sustain higher mortality. To evaluate these hypotheses, I quantified nest site selection patterns of multiple species of ground-nesting dabbling ducks in areas where predation pressure was normally high, and compared these patterns to those on areas where predation was relaxed. Predation pressure was experimentally reduced by removing common predators of duck nests and females (mainly red foxes, coyotes, skunks and raccoons) on some study areas and not on others (controls). Predator removal and natural causes produced a 10-fold difference in duck nesting across study sites, allowing for investigation of effects of predation pressure on nest site selection of ducks. Coarse scale habitat selection patterns were similar to results reported in previous studies; blue-winged teal and northern shoveler were found more often in native grassland than in other habitat types, while gadwall and mallard nests occurred more frequently in shrub patches when compared with other habitat patches. A difference in nest site characteristics was observed between hatched and depredated nests for gadwall and northern shoveler but not for blue-winged teal and mallard. However, in all species, the nest site selection patterns were non-random. Thus, the process of nest predation did not shape patterns of nest site choice. Contrary to predictions, inter-specific overlap in nest site features was not related to predation pressure: nests that overlapped most with features of other species did not suffer higher predation, nor did inter-specific overlap in nest characteristics decrease during the nesting season. These findings were inconsistent with the hypothesis that community-level patterns of nest site use are differentiated as a result of predation pressure. Long-term work on nest site use by individually marked females of numerous ground-nesting bird species would be informative, as would experimental studies of other hypotheses about factors affecting nest site choices in birds.

Nesting success is an important vital rate affecting the reproductive fitness of birds, and predation typically is the single most important factor affecting nesting success. Presumably, birds should nest in locations that maximize nest survival. If specific nest characteristics increase the probability that a nest will hatch, natural (phenotypic) selection could favour use of sites with these features, producing nonrandom patterns of nest site use. Alternatively, birds that are highly selective in nest site choices might be at a disadvantage if predators learn to forage preferentially in these locations and improve their efficiency in depredating nests; in this case, random nesting patterns could be favoured. Finally, it has been hypothesized that predation pressure can influence nest site selection patterns of entire bird communities. If predators develop a search image to hunt for bird nests, then nests that are most similar to each other, irrespective of species, should sustain higher mortality. To evaluate these hypotheses, I quantified nest site selection patterns of multiple species of ground-nesting dabbling ducks in areas where predation pressure was normally high, and compared these patterns to those on areas where predation was relaxed. Predation pressure was experimentally reduced by removing common predators of duck nests and females (mainly red foxes, coyotes, skunks and raccoons) on some study areas and not on others (controls). Predator removal and natural causes produced a 10-fold difference in duck nesting across study sites, allowing for investigation of effects of predation pressure on nest site selection of ducks. Coarse scale habitat selection patterns were similar to results reported in previous studies; blue-winged teal and northern shoveler were found more often in native grassland than in other habitat types, while gadwall and mallard nests occurred more frequently in shrub patches when compared with other habitat patches. A difference in nest site characteristics was observed between hatched and depredated nests for gadwall and northern shoveler but not for blue-winged teal and mallard. However, in all species, the nest site selection patterns were non-random. Thus, the process of nest predation did not shape patterns of nest site choice. Contrary to predictions, inter-specific overlap in nest site features was not related to predation pressure: nests that overlapped most with features of other species did not suffer higher predation, nor did inter-specific overlap in nest characteristics decrease during the nesting season. These findings were inconsistent with the hypothesis that community-level patterns of nest site use are differentiated as a result of predation pressure. Long-term work on nest site use by individually marked females of numerous ground-nesting bird species would be informative, as would experimental studies of other hypotheses about factors affecting nest site choices in birds.

Natural regeneration is used to restock trembling aspen (Populus tremuloides Michx.) cutblocks and factors controlling regeneration are areas of interest and concern to the forest industry. Harvest operations in Manitoba require that coarse woody debris, or slash, be left and distributed in cutblocks. The objective of this study was to investigate the effects of slash loading on soil temperatures and aspen regeneration, and implications for harvest operations in the Duck Mountain area. Early sucker growth, initiation, and soil temperatures were surveyed in six winter and six summer cutblocks under different levels of slash loadings. A growth chamber study, using field temperature data as a guideline, examined the effects of diurnal temperature variation on sucker initiation and production. In winter and summer cutblocks, mean depths to sucker initiation from the parent root were 4.6 + 2.4 cm and 3.4 + 2.1 cm, respectively, and initiation of suckers occurred mainly from parental roots located in the LFH layer. Daily mean soil temperatures during the growing season were significantly lower under higher levels of slash (difference of 3.6 oC during May). Higher amounts of slash also significantly shortened the length of the growing season (89 fewer days above 0 oC in one season) and decreased the number of suckers produced (150 000 ha1 decreased to 14 000 ha-1), sucker volume (decreased by 256 cm3m-2) and leaf area index (decreased by 0.9). There was no difference in sucker production between any diurnal temperature treatments in the growth chamber study. Shallow depth to sucker initiation has important implications for harvest operations using heavy machinery especially those occurring during the summer season. Moderate levels of slash in summer cutblocks, and heavy levels of slash in winter cutblocks limit sucker growth. Although slash decreases diurnal temperature amplitudes, this may not be the reason for the decrease in sucker production associated with increased levels of slash. Both soil temperature and early sucker growth are strongly affected by slash loading; by monitoring harvest operations and the distribution of slash within cutblocks, the negative effect of heavy machine traffic and heavy piles of slash can be reduced and ensure successful forest regeneration.

Environmental conditions on wintering or spring-staging areas may influence subsequent reproductive performance in migratory birds. These cross-seasonal effects may result from habitat loss and degradation (e.g., via contamination) which in turn reduce reproductive success, particularly in waterfowl that use stored nutrients for reproduction. North American lesser scaup (<i>Aythya affinis</i>) and white-winger scoter (<i>Melanitta fusca</i>) numbers have declined over the past 20 years, particularly in the boreal forest, and remain well below conservation goals, whereas ring-necked duck (<i>A. collaris</i>) numbers have increased. Environmental changes on scaup and scoter wintering and staging areas have raised concern about possible cross-seasonal effects on birds arriving on breeding grounds. The spring condition hypothesis (SCH) purports that many female scaup fail to acquire sufficient nutrients in late winter and spring, causing a decrease in breeding propensity and productivity. The contaminant hypothesis proposes that increased exposure to contaminants (particularly selenium [Se]) on wintering and staging areas has decreased scaup productivity. Accordingly, I compared body condition and studied Se concentrations in scaup, scoters and ringnecks to test the condition and contaminant hypotheses. <p>Scaup had similar body condition to ringnecks, and had similar body mass compared to scaup collected near Yellowknife, NT, in 1968-70. There was no relationship between scaup and ringneck nutrient levels and claw tip carbon, nitrogen or hydrogen isotope values, suggesting that arrival body condition likely was not related to location or diet several months prior. Instead, scaup and ringnecks nutrient levels may be more affected by feeding or habitat conditions on or near the breeding grounds. Scaup had slightly higher liver Se concentrations than ringnecks, but levels in both species were below recognized harmful threshold concentrations; I found no relationship between Se and breeding propensity, or between Se and somatic lipid or protein stores. Scoters had much higher Se concentrations, yet contrary to predictions, there were positive relationships between Se and both lipid stores and breeding status. Follicle [Se] in scaup was below threshold concentrations; despite high liver Se in scoters, egg and follicle levels also were well below threshold concentrations. Using both body composition analysis and stable-isotope analysis I determined that scoters derive egg protein from their breeding ground diet, which likely prevents Se deposition from somatic protein to eggs, and egg lipids are apparently derived from somatic tissues. In all three species, liver Se concentrations were significantly correlated with claw tip ä15N. As the claw tip likely represents assimilated diet from 2-5 months prior to sampling, this correlation suggests that Se in these boreal breeding species is carried over from wintering and staging areas. <p>Overall, results did not support either the spring condition or contaminant hypotheses. Scaup and scoters are late-nesting species, with highest pair densities occurring at the northern extent of their range. Maximum ring-neck pair densities occur at more southern latitudes. Ring-necks also nest earlier and appear to be more flexible in timing of nest initiation. Therefore, it is possible that due to climate change, early spring conditions alter the optimal timing of nest initiation to the detriment of late-nesting species such as scaup and scoters, and favour earlier nesters like ringnecks. Further research into this mismatch hypothesis is warranted.

Differences in the expression of antimicrobial peptides in vivo have been proposed as underlying factors influencing susceptibility to infection. In this context, the role of avian b-defensins in inhibiting avian influenza infections is a study object in an ongoing collaboration with the Zoonotic Ecology and Epidemiology group at Lnu. In this report, an attempt to synthesize two variants of the peptide Anas Platyrhynchos AvBD-8, using Fmoc-based SPPS, is described. The length of AvBD-8 (43 aa) necessitated peptide synthesis in two segments to subsequently be ligated using native chemical ligation. The first component of a 19 aa segment was thus a Dbz-linker, which would allow to ligate this end with a second segment (24 aa). Halfway through the synthesis of this larger segment the batch was split into two pots, allowing the synthesis of two segments differing by one single amino acid (R for W). The composition of these segments were: Dbz-HDTSCTGGAQKCQVANNPA (Dbz-segment), SVVTRCCPIGQKCWGFARTNPPPC(boc) (W-segment), and  SVVTRCCPIGQKCRGFARTNPPPC(boc) (R-segment). Crude product yields were 284,5 mg; 67,6% (Dbz-segment), 137,6 mg; 52,3% (W-segment), and 166,3 mg; 64,2%. Preliminary mass spectrometric analysis on the crude products did not indicate the presence of the desired segments in major mass peaks. Further product purification is necessary in order to allow definite conclusions, but it appears as if the synthesis has not worked. Possible explanations are either impure or degraded reactant(-s), folding or shielding effects of the growing peptide chain at some point inhibiting synthesis, or experimental errors during one or more of the many steps involved in the synthesis.

No description available.

Sixteen adult male and 8 adult female post moult mallards were equipped with radio transmitters, in a two year study (1977-6AHY-M and 4AHY-F; 1978-10AHY-M and 4AHY-F). Field-feeding was monitored at a lure crop and on adjacent grain fields. Ninety-two percent of the mallards radio-equipped were recorded at a field-feeding site at least once with 71% recorded field-feeding within one week. There was no significant difference in field-feeding activity between males and females. In the morning during periods of rain, mallards field-fed 0.55h longer, arriving 0.30h later and departing 0.9h later than mallards field-feeding during clear weather. The morning field-feeding period was longer in duration than the evening foeld-feeding period. Light intensity was the dominant climatological variable contributing to the arrival of mallards in the morning during periods of no rain (multiple R2=68.1%) and rain (R2=69.5%). Light appeared to act as an initiating cue for morning feeding activity. A high correlation existed between duration of stay during periods of no rain (r=0.815) and rain (r=0.860) suggesting that mallards remained longer at a field-feeding site in the morning by departing later, not arriving earlier. Light intensity was also the dominant climatological variable contributing to the arrival of mallards in the evening amongst those mallards which field-feed in both the morning and evening (R2=78.1%) and those which field-fed in the evening only (R2=63.3%). In addition, light intensity was the only contributing factor in the evening for all mallards departing a field-feeding site (R2=72.7%). Mallards were never recorded field-feeding longer than 15 minutes after there was non measurable light...

Redhead duck (Aythya americana) nesting and habitat change was studied in Knudson Marsh, Utah, in 1974 and 1975, and compared with earlier studies from 1950 and 1955 on the same marsh. Water conditions in 1975 were found to be similar to those in 1950, both years of favorable habitat, yet there was a decline in numbers of redheads from 500 pairs in 1950 to 50 pairs in 1975. The number of nests found also declined from 151 in 1950 to 49 in 1975. Water conditions were poor in 1955 and slightly more favorable in 1974, but there was a decline from 95 pairs and 49 nests in 1955 to 50 pairs and 23 nests in 1974. Success of active nests was greater in the present study than in 1950, but hatching success in successful nests was greater in 1950. No appreciable change in the vegetational composition of the marsh was detected between 1950 and the present study.

Sixteen adult male and 8 adult female post moult mallards were equipped with radio transmitters, in a two year study (1977-6AHY-M and 4AHY-F; 1978-10AHY-M and 4AHY-F). Field-feeding was monitored at a lure crop and on adjacent grain fields. Ninety-two percent of the mallards radio-equipped were recorded at a field-feeding site at least once with 71% recorded field-feeding within one week. There was no significant difference in field-feeding activity between males and females. In the morning during periods of rain, mallards field-fed 0.55h longer, arriving 0.30h later and departing 0.9h later than mallards field-feeding during clear weather. The morning field-feeding period was longer in duration than the evening foeld-feeding period. Light intensity was the dominant climatological variable contributing to the arrival of mallards in the morning during periods of no rain (multiple R2=68.1%) and rain (R2=69.5%). Light appeared to act as an initiating cue for morning feeding activity. A high correlation existed between duration of stay during periods of no rain (r=0.815) and rain (r=0.860) suggesting that mallards remained longer at a field-feeding site in the morning by departing later, not arriving earlier. Light intensity was also the dominant climatological variable contributing to the arrival of mallards in the evening amongst those mallards which field-feed in both the morning and evening (R2=78.1%) and those which field-fed in the evening only (R2=63.3%). In addition, light intensity was the only contributing factor in the evening for all mallards departing a field-feeding site (R2=72.7%). Mallards were never recorded field-feeding longer than 15 minutes after there was non measurable light...