We used satellite telemetry methods to study macaroni penguins at South Georgia to determine how they ranged from their colonies during the early part of their breeding season at a time when they are constrained to return to their chicks on a near-daily basis. The principal objectives of this study were to examine whether these penguins exploit major oceanographic features where prey may be more predictable, whether birds from one colony forage in separate locations to those from nearby colonies, or whether they range evenly over the available area. Results show that the penguins did not range evenly, that birds from one colony tended to forage in locations separate from those used by birds from nearby colonies (or at least overlap was restricted), and that though birds from some colonies foraged within waters influenced by major oceanographic features such as the southern Antarctic Circumpolar Current front, not all birds in the region focused on such areas, as some birds foraged in other oceanographic contexts. The results from this study highlight the complexity of foraging dynamics for colonially nesting seabirds; they also help inform management models currently being developed for Antarctic krill fisheries, which are a potential competitor for the main prey of macaroni penguins. KEY WORDS: Macaroni penguin · Foraging · Oceanography · Satellite telemetry · South Georgia Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 323: [239][240][241][242][243][244][245][246][247][248][249][250][251] 2006 seabird species (de le Brooke 2004). Thus, given the oceanographic context in which macaroni penguins forage, it is critically important to understand how their foraging decisions are influenced by local conditions in order to better understand the motivating factors governing their foraging behaviour.Previous satellite telemetry studies describing the foraging locations of macaroni penguins are available (Barlow & Croxall 2002, Barlow et al. 2002, Trathan & Croxall 2004. They have so far only been conducted from Bird Island, a small offshore island near South Georgia. These studies indicate that macaroni penguins are very much constrained during the early stages of chick rearing, particularly during the broodguard period (Barlow & Croxall 2002, Trathan & Croxall 2004, when only females forage, with trips lasting on average about 12 h (Croxall et al. 1993). During brood-guard, males stay ashore and guard their chicks, which grow rapidly, increasing in weight by more than 1200 g (Williams 1995) over the course of the brood-guard period (approximately 20 d). Female penguins tracked from Bird Island during brood-guard are very conservative in their foraging locations, travelling along a relatively restricted set of bearings (Barlow & Croxall 2002, Trathan & Croxall 2004. This is despite the fact that Bird Island is small and foraging could potentially occur over a much wider area. The reasons why macaroni penguins forage along such a restricted set of bearings ar...

Studies n the daily activity of Glossina longipennis at Galana Ranch using a black odour-baited electrocuting target confirmed its crepuscular activity profile. Activity started at 05.00-05.30 hours and peaked at 06.00-06.30 hours, stopped by 09.00 hours, then started again at 17.00-17.30 hours with a peak at 18.30-19.00 hours, ceasing by 19.30 hours. Females made up 60% of the overall catch, and tended to arrive later than males. Other stationary sampling methods (trap, stationary ox) gave similar results. With the stationary methods, very few flies were caught outside the periods of peak activity (only 1.5% of the total between 09.00 and 17.00 hours); the ox was the only stationary bait to catch any flies between 10.00 and 16.00 hours. More flies were caught throughout the day at mobile baits (8.3% of the male and 2.3% of the female catch was taken between 09.00 and 17.00 hours). Mobile baits caught considerably more males than females (females were 17% of the catch). These males had on average higher fat and haematin reserves. Similar nutritional differences were not observed for females. There were fewer older females (ovarian category 3 or more) in mobile compared to stationary baits, and a lower proportion of the youngest males (wing fray category 1) at natural compared with artificial baits.

No abstract

No abstract