Diurnal activity budgets of Black Ducks during their

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for other species (e.g., Sayler and Afton 1981). Crepuscular peaks in feeding activity were noted only during winter at the tidal causeway area (Table 2). A.

Diurnal activity budgets of Black Ducks during their annual cycle in Prince Edward Island T. EARLEHICKEY'

AND

RODGER D. TITMAN

Department of Renewable Resources, Macdonald College of McGill University, Ste . Anne de Bellevue, P.Q ., Canada H9X 1CO Received June 14, 1982

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HICKEY, T. E., and R. D. TITMAN.1983. Diurnal activity budgets of Black Ducks during their annual cycle in Prince Edward Island. Can. J. Zool. 61: 743-749. Scan sampling (N = 68 193 observations) and continuous observation (N = 659 h) of Black Ducks (Anas rubripes) in Prince Edward Island between 19 April 1976 and 1 September 1977 were used to estimate their seasonal activity budgets. Percent of time spent resting increased with increasing wind chill during fall (47.9-63.5%) and winter (76.9-85.5%). Ducks fed less and rested more with increasing tide level during all seasons. Females spent more time feeding than their mates during late winter (9.7%) and the breeding season (15.1%). Behavior of pairs varied depending on the habitat occupied. Feeding was the major activity of Black Duck pairs and of brood hens and ducklings. Resting dominated fall and winter behavior although some sites were more important for foraging during winter. Behavioral changes between seasons apparently reflect different strategies employed by Black Ducks within their yearly cycle.

HICKEY, T. E., et R. D. TITMAN.1983. Diurnal activity budgets of Black Ducks during their annual cycle in Prince Edward Island. Can. J. Zool. 61: 743-749. Des observations ponctuelles (N = 68 193 observations) et des observations continuelles (N = 659 h) de Canards noirs (Anas rubripes) sur 1'Ile du Prince Edouard entre le 19 avril 1976 et le ler septembre 1977 ont perrnis d'Ctablir le bilan des activitCs saisonnieres de ces oiseaux. Le pourcentage de temps consacrC au repos augmente a mesure qu'augmente le froid en automne (47,9 a 63,5%) et a l'hiver (76,9 a 85,5%). Les canards se nourrissent moins et se reposent plus pendant la marCe montante, en toute saison. Les femelles consacrent plus de temps a l'alimentation que leur partenaire mile a la fin de l'hiver (9,7%) et durant la saison de la reproduction (15,1%). Le comportement des couples varie en fonction de l'habitat occupC. Chez le Canard noir, l'alimentation constitue la principale activitC des couples des femelles reproductrices et des canetons. Le repos prddomine a l'automne et au printemps, bien que certains sites soient le siege d'une plus grande activitC alimentaire durant l'hiver. Ces changements de comportement d'une saison a l'autre semblent &re la manifestation de diffdrentes stratCgies utilisCes par ces canards au cours de leur cycle annuel. [Traduit par le journal]

Introduction Activity budgets have been estimated for a variety of birds including waterfowl (see Asplund 1981). Analysis of activity budgets has helped elucidate differences in waterfowl behavior during selected seasons of the year (e.g., Siegfried 1974; Dwyer 1975; Titman 1981). Few studies, however, have followed a species throughout the annual cycle. The purpose of this study was to document changes in the diurnal activity budgets of Black Ducks (Anas rubripes) throughout the year. Habitats utilized, time of day, level of tide, and severity of wind chill were predicted to influence the amount of time spent in various activities. Analysis of activity budgets within and between seasons was expected to illustrate adaptive strategies used during the Black Duck's annual cycle. Study area and methods Prince Edward Island is within the Black Duck's breeding and wintering range (Bellrose 1976), permitting observation 'present address: Hardy Associates (1978) Ltd., 900 Windmill Road, Dartmouth, N.S., Canada B3B 1P7.

throughout the year. A small proportion of the population is ~ & l e t t (1961) sedentary ( ~ a i l e t t 196 1 ; ~ i c k e1980). ~ classified waterfowl habitat in Prince Edward Island into three general types: (i) inland freshwater areas, including farm and mill ponds and freshwater portions of streams and rivers, (ii) inland tidal waters consisting of tidal portions of rivers, and (iii) coastal waters including coastal salt marshes and areas associated with causeways and harbors which remain ice free during winter. In addition to these habitats, we also observed Black Ducks utilizing harvested agricultural land during fall, winter and the breeding season. We classified periods of observation on the basis of changes in behavior of ducks and(or) environmental conditions. Winter extended from freezeup until dispersal of marked birds from wintering areas (1 1 December 1976 - 3 1 March 1977). Breeding extended from winter until breeding pairs were last observed (19 Avril - 12 June 1976: 1 Avril . - 22 June 1977). Postbreeding - brood rearing were combined and occurred from the time broods were first observed until dispersal in fall (1 June - 5 October 1976; 6 June - 3 1 August 1977). Overlap occurred between breeding and the postbreeding - brood rearing periods as some broods were observed while pairs (recognized by their association or aggressive behavior toward conspecifics) were still evident. Fall coincided with initiation of hunting and extended until freezeup (6 October - 10 x

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CAN. J. ZOOL. VOL. 61, 1983

December 1976). We sampled 57,64,9 1, and 25 days during each season, respectively. We observed ducks during daylight hours from a vehicle or blinds. Observations were made with a telescope (15-60 x ) and recorded with a portable cassette recorder. An attempt was made to sample all daylight hours every 10 days. Occasionally this was not possible owing to the difficulty in locating birds and the generally wary nature of the Black Duck. Activity budgets were compiled primarily from observations of unmarked birds. One-third of the observations used in the analysis of time spent feeding in relation to tide level during postbreeding - brood rearing involved marked birds. Black Ducks were captured in winter and spring with funnel bait traps (Day et al. 1980, p. 76); flightless birds were captured with a dog or while nightlighting with an airboat (Bishop and Barrett 1969). Birds were banded and individually marked (139 in summer, 133 in winter) with patagial tags on both wings (Anderson 1963) for a concurrent study of Black Duck movements (Hickey 1980). Broods were aged (Gollop and Marshall 1954) and were not marked until they were at least 25 days of age (class IIa). The Atmospheric Environment Service at Charlottetown (46"17' N , 63O08 ' W) supplied hourly temperatures (degrees Celsius) and wind speeds (kilometres per hour) for calculation of wind chill. We categorized cooling rates as: (i) light ( S 1000 w/m2), (ii) moderate (100 1- 1374 w/m2), and (iii) severe (21375 w/m2). Sunrise and sunset times (AST) for Charlottetown were used to divide the day into three parts: (i) early (sunrise plus 1.5 h), (ii) late (from 1.5 h preceding sunset), and (iii) midday (remaining daylight hours). Tides ranged from 1.8 m on the coast to 0.5 m on inland tidal areas. We used hourly tide levels recorded by Environment Canada at Charlottetown or predicted from tide tables. Low, mid, and high tides were determined around means for each area and therefore reflect relative changes at each area. Observations were categorized to time period and tide and wind-chill level during data analysis. We used scan and focal-animal (continuous observation) sampling (Altmann 1974) to record behavioral activity, expressed as percent of time spent in each activity. Scan sampling was used when large groups of ducks were visible (fall and winter) and focal-animal sampling was employed when observing individual birds or small groups (

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