Forced copulation in sympatric American black ducks and mallards in Nova Scotia

1990 ◽  
Vol 68 (8) ◽  
pp. 1691-1696 ◽  
Author(s):  
N. R. Seymour
Keyword(s):  
Nova Scotia ◽  
Breeding Season ◽  
Breeding Period ◽  
Lawrence Estuary ◽  
Qualitative And Quantitative ◽  
Black Duck ◽  
Forced Copulation ◽  
American Black ◽  
St Lawrence Estuary

Observations of primarily identifiable wild black ducks and mallards provided qualitative and quantitative descriptions of interactions within and between intraspecific, interspecific, and heterospecific pairs throughout the breeding season. The study was carried out in a watershed on the St. Lawrence estuary shore of Nova Scotia from 1972 to 1988. Attempted forced copulation and forced pair copulation were rare among black ducks at any time throughout the breeding period. Only two apparently successful forced copulations were observed. Territorial males chased both female black ducks and mallards, and these chases appeared motivated by hostility. Males that had left their mates/territories did not attempt forced copulation with other females. Females sometimes avoided strange males, particularly when they returned to territories from their nests. Paired males rarely approached females with broods. Male mallards chased both female mallards and black ducks, and did not appear to discriminate between species when attempting forced copulation. Male mallards were more persistent and vigorous in their chases than black ducks, and they attempted forced copulation, whether with black ducks or mallards, more frequently than male black ducks did. Apparently successful forced copulation between a male mallard and female black duck occurred on three occasions.

Changes in activity patterns, agonistic behavior, and territoriality of black ducks (Anas rubripes) during the breeding season in a Nova Scotia tidal marsh

1978 ◽  
Vol 56 (8) ◽  
pp. 1773-1785 ◽  
Author(s):  
Norman R. Seymour ◽  
Rodger D. Titman
Keyword(s):  
Nova Scotia ◽  
Breeding Season ◽  
Activity Patterns ◽  
Quantitative Description ◽  
Egg Laying ◽  
Spatial Displacement ◽  
Lawrence Estuary ◽  
Qualitative And Quantitative ◽  
Males And Females ◽  
St Lawrence Estuary

Observations of marked wild black ducks provided a qualitative and quantitative description of hostile interactions between pairs throughout the breeding season. This study was carried out on a tidal estuary on the St. Lawrence estuary shore of Nova Scotia from 1972 to 1974. Interactions occurred first on the communal part of the marsh and later on territories.Territories corresponded to tidal ponds (0.16–3.8 ha) at the marsh periphery and were established only after pairs were on the marsh 30–40 days. Territories were established approximately 5 days before egg laying began and females were responsible for their location. Females spent approximately 45 days on the territory and males stayed 27–32 days. Males remained almost continuously on territories during the prelaying and laying periods but left both females and territories during midincubation.The activity of males and females of pairs was analysed and compared according to three activities: foraging, loafing, and hostility. Females foraged at a faster rate and for longer durations than their mates in both the preterritorial and territorial periods. Hostility by territorial males toward intruding pairs provided seclusion for resident pairs. Changes in the form and intensity of hostility led to the spatial displacement of pairs. The pursuit flight by males was the main mechanism in the establishment and maintenance of territories.

Reproductive variables of American black ducks along the St. Lawrence estuary, 1963-1991

1998 ◽  
Vol 76 (6) ◽  
pp. 1165-1173 ◽  
Author(s):  
Luc Bélanger ◽  
Austin Reed ◽  
Jean-Luc DesGranges
Keyword(s):  
Clutch Size ◽  
Nesting Success ◽  
Laying Date ◽  
Peat Bogs ◽  
Mixed Stands ◽  
Lawrence Estuary ◽  
Julian Date ◽  
Black Duck ◽  
American Black ◽  
St Lawrence Estuary

We examine data from different surveys conducted from 1963 to 1991 in the Baie de l’Isle Verte National WildlifeArea and the surrounding offshore islands, an approximately 20-km2 coastal segment of the St.Lawrence estuary in Quebec.We summarize data regarding various aspects of the nesting ecology of the American black duck (Anas rubripes) (n = 812nests). Mean laying date, average clutch size, and apparent nesting success did not differ among years (P > 0.05). Black ducksnested earlier on islands (mean Julian date 120.0 vs. 121.3;P = 0.03), but mean clutch size and nesting success on islands didnot differ from those on the mainland (P> 0.05). Among mainland-nesting black ducks, those nesting in mixed stands of treesand bushes initiated nests almost 10 days earlier than those nesting in the two other types of nest cover (mean Julian date 124.0vs. 134.4 and 139.6). Black ducks nesting in such habitats as woodlots, peat bogs, or shrubland laid a larger number of eggsthan those nesting in the two other habitat types (mean 9.7 vs. 8.8 and 9.4). Finally, we observed that nesting success of ducksnesting in woodlots, peat bogs, and shrubland and in mixed stands of trees and bushes or of herbaceous plants and shrubs wasup to three times higher than at other sites (P<= 0.05). We conclude that in addition to protection and restoration of existingislands, more emphasis should be placed on conserving peat bogs, coniferous woodlots, and shrubland, because they alsoconstitute good mainland-nesting habitat for black ducks along the St. Lawrence estuary.

scholarly journals Do Barrow's Goldeneyes, Bucephala islandica, Breed South of the St. Lawrence Estuary in the Gaspé Peninsula, Eastern Canada?

2010 ◽  
Vol 124 (2) ◽  
pp. 179
Author(s):  
Jean-François Ouellet ◽  
Pierre Fradette ◽  
Isabel Blouin
Keyword(s):  
North America ◽  
Breeding Season ◽  
Breeding Habitat ◽  
Eastern North America ◽  
Eastern Canada ◽  
Lawrence Estuary ◽  
North Shore ◽  
The North ◽  
Bucephala Islandica ◽  
St Lawrence Estuary

We report the first observations of Barrow's Goldeneyes south of the St. Lawrence estuary in typical breeding habitat during the breeding season. Until recently, the confirmed breeding locations for the species in Eastern North America were all located on the north shore of the Estuary and Gulf of St. Lawrence.

Habitat segregation among the age groups of Gasterosteus aculeatus (Pisces: Gasterosteidae) in the middle St. Lawrence estuary, Canada

1990 ◽  
Vol 68 (6) ◽  
pp. 1202-1208 ◽  
Author(s):  
Paul Picard Jr. ◽  
Julian J. Dodson ◽  
Gérard J. FitzGerald
Keyword(s):  
Breeding Season ◽  
Gasterosteus Aculeatus ◽  
Age Groups ◽  
Minimum Size ◽  
Spawning Period ◽  
Lawrence Estuary ◽  
Age Related ◽  
Tidal Rivers ◽  
Marsh Pools ◽  
St Lawrence Estuary

Previous studies of migratory populations of sticklebacks (Pisces: Gasterosteidae) have been exclusively limited to their biology on the spawning grounds during the spring breeding season. In 1985 and 1986, we studied the ecology of the threespine stickleback (Gasterosteus aculeatus) in three subhabitats of the middle St. Lawrence estuary before, during, and after the breeding season: (i) the open waters of the estuary, (ii) a series of intertidal salt marsh pools, and (iii) two tidal rivers (Rivière des Vases and Rivière Trois-Pistoles). In spring, our catch data in the various subhabitats showed that adults moved from the open waters of the estuary towards the tidal rivers and tide pools. Catches of adults in all subhabitats subsequently declined, whereas the young of the year (age 0+) became increasingly abundant. In this area, G. aculeatus live for 2 years and are physiologically capable of breeding during their first summer as adults. However, we found age-related differences in habitat use between the two adult year classes. Age 1+ fish were never more abundant than age 2+ fish in Rivière des Vases, in the tide pools, and in the open waters of the estuary, whereas age 1+ fish were more abundant than age 2+ fish in Rivière Trois-Pistoles. Throughout the breeding season, gonadosomatic indices of female G. aculeatus were the same for the two age groups. Total lengths of age 0+ fish captured in the various subhabitats suggest that the major spawning period is limited to May and June. Age 0+ fish do not leave the tide pools for the open waters of the estuary before having attained a certain minimum size.

Habitat-related variation in movements and fledging success of American black duck broods in northeastern Nova Scotia

1996 ◽  
Vol 74 (6) ◽  
pp. 1158-1164 ◽  
Author(s):  
Norman Seymour ◽  
Winston Jackson
Keyword(s):  
Nova Scotia ◽  
Tidal Marsh ◽  
Freshwater Wetlands ◽  
Fledging Success ◽  
Black Duck ◽  
Brood Movement ◽  
American Black ◽  
American Black Duck ◽  
In Transit ◽  
Three Rivers

Female American black ducks (Anas rubripes) are known to move their broods from low- to high-nutrient rearing sites. We studied the extent of brood movement and fledging success in a northeastern Nova Scotia watershed. Annually, about half the broods moved either overland or along three rivers from small, widely dispersed oligotrophic–mesotrophic wetlands to a large hypertrophic tidal marsh. Mean brood size at fledging was 3.50 in the tidal marsh but 7.05 at the dispersed freshwater wetlands. Females that remained at dispersed sites fledged more ducklings than females that moved to the marsh. Attrition occurred predominantly in the marsh or in transit. Females fledged fewer young when they raised broods at the marsh than when the same females raised broods at inland sites. Females were as successful at nutrient-poor sites as at nutrient-rich sites. The study suggests that concentrating birds in nutrient-rich sites may be counterproductive in terms of female reproductive fitness and population recruitment.

Breeding-season habitat use by sticklebacks (Pisces: Gasterosteidae) at Isle Verte, Quebec

1989 ◽  
Vol 67 (9) ◽  
pp. 2126-2130 ◽  
Author(s):  
F. G. Whoriskey ◽  
G. J. Fitzgerald
Keyword(s):  
Salt Marsh ◽  
Habitat Use ◽  
Breeding Season ◽  
Habitat Choice ◽  
Lawrence Estuary ◽  
Use Patterns ◽  
Tidal Salt Marsh ◽  
Large Numbers ◽  
Marsh Pools ◽  
St Lawrence Estuary

We examined habitat use patterns of three species of sticklebacks as they moved from the St. Lawrence estuary into tidal salt marsh pools to breed. All three species apparently avoided pools that dried out and settled more often in pools that retained their water. Habitat choice by immigrants was not influenced by either the presence of the most aggressive species or by resident fish density. Movements of fish into the marsh and densities of fish in the pools peaked on the first days of the approximately 7-day flooding cycles, and declined thereafter. Thus, large numbers of fish moved away from these pools after initially settling in them, but the reason for this and the subsequent fate of the fish is unknown.

scholarly journals Increases in the Number of American Black Ducks Wintering in Nova Scotia, 1970–2015

2017 ◽  
Vol 8 (2) ◽  
pp. 669-675 ◽  
Author(s):  
Gregory J. Robertson ◽  
Molly Tomlik ◽  
G. Randy Milton ◽  
Glen J. Parsons ◽  
Mark L. Mallory
Keyword(s):  
Time Series ◽  
Nova Scotia ◽  
Negative Binomial ◽  
Random Effect ◽  
Annual Trend ◽  
Management Actions ◽  
Entire Time ◽  
Black Duck ◽  
Time Period ◽  
American Black

Abstract Despite extensive conservation and management efforts, American black duck (Anas rubripes) populations remain below desired population levels. Researchers have noted declines at a number of wintering areas, but indications are that wintering populations in the northern part of the range are increasing. Intermittently between 1970 and 1989, and annually since 1992, wildlife biologists have flown aerial surveys of the entire coast of Nova Scotia, Canada, to count wintering waterfowl. This survey counted the total number of ducks seen in predefined lengths of coastline. We analyzed those survey data using generalized linear mixed models, over the entire time period (1970–2015) and in the recent time period (1992–2015, when surveys were done every year), across five general regions of Nova Scotia. We fit models using Bayesian methods with uninformative priors; models with negative binomial response distributions performed well. Due to the large variation in mean numbers of black ducks across the predefined lengths of coastline, we treated these blocks of coastline as a fixed effect, while annual trend (slope) was modeled as a random effect to account for variation in annual trend across blocks of coastline. Results were similar between the entire time series (1970–2015) or the most recent and more complete time series (1992–2015). In general, numbers of wintering black ducks in Nova Scotia increased (1.0–16.0%/y) and increases were significant (Bayesian credible intervals did not bound 0) in four of five regions. Increasing numbers in Nova Scotia are consistent with other observations of increasing wintering numbers at the northern range of American black ducks and may indicate a shift in the wintering range that has been ongoing for decades. Future habitat management actions will benefit from consideration of regional trends and the distributional change of black duck.

An empirical evaluation of landscape energetic models: Mallard and American black duck space use during the non-breeding period

2015 ◽  
Vol 79 (7) ◽  
pp. 1141-1151 ◽  
Author(s):  
William S. Beatty ◽  
Elisabeth B. Webb ◽  
Dylan C. Kesler ◽  
Luke W. Naylor ◽  
Andrew H. Raedeke ◽  
...  
Keyword(s):  
Empirical Evaluation ◽  
Space Use ◽  
Breeding Period ◽  
Black Duck ◽  
American Black ◽  
American Black Duck

Erratum: Response of the sea urchin, Strongylocentrotus droebachiensis, to reduced salinities: importance of size, acclimation, and interpopulation differences

1984 ◽  
Vol 62 (11) ◽  
pp. 2352-2352 ◽  
Author(s):  
John H. Himmelman ◽  
Helga Guderley ◽  
Gilles Vignault ◽  
Guy Drouin ◽  
Peter G. Wells
Keyword(s):  
Nova Scotia ◽  
Strongylocentrotus Droebachiensis ◽  
Test Diameter ◽  
Lawrence Estuary ◽  
Stress Acclimation ◽  
Hypoosmotic Stress ◽  
Size Groups ◽  
Percentage Weight ◽  
St Lawrence Estuary ◽  
Neuromuscular Coordination

Weight change, mortality, and neuromuscular coordination, as measured by righting time, were used to evaluate the resistance of Strongylocentrotus droebachiensis to hypoosmotic stress. Acclimation to a salinity of 24 or 25‰ decreased the righting time of urchins after 96 h of hypoosmotic stress. The effect of acclimation was the same for four size groups of urchins (10–15, 20–25, 34–37, and 50–60 mm in test diameter). A comparison of urchins from the St. Lawrence Estuary and from Nova Scotia, both acclimated to 24‰, showed that for the three larger size classes, the salinity at which there was a significant increase in righting time was lower for urchins from an estuarine environment than for urchins from the oceanic environment. The percentage weight gain following hypoosmotic stress increased with decreasing urchin size. For small urchins the increase was less marked after acclimation to 24‰. The mortality rates following these experiments showed that acclimation to a reduced salinity increased the tolerance to hypoosmotic stress, that urchins from the St. Lawrence Estuary were better able to withstand low salinities than urchins from Nova Scotia, and that small urchins were more sensitive to osmotic stress than large urchins. The latter was confirmed in a field experiment in which four size groups of urchins were kept in cages at a location exposed to periodic decreases in surface salinities.

Barnacle recruitment on ice-scoured shores in eastern Canada

2008 ◽  
Vol 88 (2) ◽  
pp. 289-291 ◽  
Author(s):  
Elizabeth A. MacPherson ◽  
Ricardo Scrosati ◽  
Patrick Chareka
Keyword(s):  
Nova Scotia ◽  
Sea Ice ◽  
Structural Complexity ◽  
Semibalanus Balanoides ◽  
Eastern Canada ◽  
Lawrence Estuary ◽  
Selective Pressures ◽  
Larval Behaviour ◽  
Recruitment Patterns ◽  
St Lawrence Estuary

Previous observations in the St Lawrence Estuary (eastern Canada) suggested that larvae of intertidal barnacles (Semibalanus balanoides) would settle almost exclusively inside crevices on shores that are scoured by sea ice every winter. It was suggested that the strong ice scour in winter on that coast (which removes organisms outside of crevices) would select for such a larval behaviour. We tested the generality of this pattern by sampling other ice-scoured shores within the Gulf of St Lawrence system. In particular, we surveyed a shore in Nova Scotia where exposed habitats (subjected to strong ice scour in winter) are interspersed with sheltered habitats (which suffer milder ice scour). Such a topographical complexity might allow for the coastal larval pool to contain a proportion of larvae that have no particular settlement preference for crevices, as selective pressures for such a behaviour would be minimal in ice-sheltered habitats. Consistently with this notion, barnacle recruits (which appear after the winter ice melts) occurred abundantly both inside and outside of crevices across the shore in the spring seasons of 2005 and 2006. Average recruit density on rocky surfaces ranged between 337 and 588 recruits dm−2, depending on the habitat. It is therefore possible that barnacle recruitment patterns on ice-scoured shores may be affected indirectly by the structural complexity of the coast.

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