The numbers of gentoo penguins Pygoscelis papua breeding at subantarctic Marion Island fell by 40% from 1994/95 to 2002/03, from 1 352 pairs to 806 pairs. Apart from a slight increase in 1998/99, there was a steady decrease in numbers breeding between 1995/96 and 2000/01, when the population stabilized. There is indication that in some years not all breeders nested and that some birds relocated to another colony after disturbance. From first clutches, pairs on average fledged between 0.01 chicks in 1997/98 and 0.58 chicks in 2002/03 (mean 0.38 ± 0.21). In 1994/95, replacement clutches increased the overall production of fledged chicks by 11%. Based on demographic parameters measured at other localities, the production of chicks at Marion Island was inadequate to maintain the population during the period 1995/96 -2000/01. Consistency in trends in breeding success at five colonies suggests that factors operating at a mesoscale, rather than those specific to particular colonies, often influenced breeding success. Laying was later than normal in 1997/98, when there was almost total breeding failure with large losses of eggs and small chicks to returning Subantarctic skuas Catharacta antarctica. Future research on this Near Threatened species at Marion Island must take full account of its susceptibility to human disturbance.
The number of Crozet shags or cormorants Phalacrocorax [atriceps] melanogenis breeding at subantarctic Marion Island decreased by 68% from 841 pairs in 1994/95 to 272 pairs in 2002/03. The mean number of pairs at colonies also decreased and was significantly related to the overall number of birds breeding in any given season. The decreases coincided with a period of warming and reduced precipitation at Marion Island and with a decrease in the number of gentoo penguins Pygoscelis papua breeding there. Both these seabird species forage inshore and there is considerable overlap in their diets. Nototheniid fish and the decapod Nauticaris marionis continued to be important in the diet of Crozet shags, but a change in dominance among nototheniid prey suggests availability of prey to shags changed after the mid 1980s. Crozet shags breed for the first time when aged three years. It is probable that about 25% of the mature population did not breed in 1997/98, coincident with a strong El Niño Southern Oscillation event. In four seasons, breeding pairs on average fledged 0.30 chicks from first clutches, an amount thought inadequate to sustain the population. Crozet shags at the Prince Edward Islands should now be regarded as Endangered. Placing breeding colonies in the most highly protected zone on Marion Island, considering the establishment of an ex situ population and undertaking a genetic study of the specific status of the Crozet shag are recommended conservation measures.
The incidental mortality of seabirds in tuna longline fisheries is estimated for the continental South African Exclusive Economic Zone (EEZ). Fishery observers accompanied 13 fishing trips and observed 108 sets (143 260 hooks) during the period 1998-2000. Despite most lines being set at night, seabird bycatch rates were high, with a mean of 1.6 birds killed per 1 000 hooks. Japanese vessels (1% effort observed) had a higher bycatch rate (2.6 birds per 1 000 hooks, range per trip 0.1-5.4) than South African vessels (0.8, range 0.0-4.3; 17% effort observed), possibly as a result of gear differences. Bird bycatch differed regionally in relation to the numbers of birds attending vessels. In international waters off the Northern Cape and southern Namibia, where there are few birds, only one bird was caught on 93 600 hooks (0.01 birds per 1 000 hooks). Shy Thalassarche cauta, black-browed T. melanophris and yellow-nosed T. chlororhynchos albatrosses, and white-chinned petrels Procellaria aequinoctialis were killed most frequently. Based on 1998-1999 fishing effort, simple extrapolation suggests that 19 000-30 000 seabirds are killed annually in South Africa's EEZ, of which 70% are albatrosses. Confidence in these estimates is low, given the small proportion of effort observed, but it is clear that urgent steps are needed to reduce seabird bycatch within South African waters.
During the austral summer of 1996/1997 we studied south polar skuas at Svarthamaren, Dronning Maud Land, Antarctica, where the world's largest known colony of Antarctic petrels is found. Our censuses suggested approximately 250 full-grown skuas and 140,000 breeding pairs of petrels were present. During their breeding season, skuas did not visit the open sea at least 200 km from the site; they relied entirely on prey caught and scavenged from the petrel colony. Because the site is so isolated, we asked whether the prey (petrels) had swamped the predators (skuas), or whether there was evidence that predator numbers were limited by the size of the prey population. Particularly at the end of the petrel incubation period, we found a close correspondence between the energy required by adult skuas and their chicks, ascertained from time budget studies, and the rate at which petrel eggs disappeared from the colony. This suggests that, in this closed system, the predator population was limited by the prey population, and that predator swamping was not an advantage that petrels gained by nesting in this remote location.
Several species of glaphyrid (Scarabaeoidea: Glaphyridae) beetles forage and mate on Mediterranean red bowlshaped flowers. In red anemones and poppies in Israel, female beetles occupy only a subset of the flowers, do not aggregate, and are hidden below the petals. This raises the question of how males find their mates. In the present study, we investigated the hypothesis that males and females orient to similar plant-generated cues, thereby increasing their mate encounter prospects. Previous studies have demonstrated that beetle attraction to red models increases with display area. Choice tests with flowers and with models indicate that both male and female beetles prefer large displays. In anemones, beetles rest, feed, and mate mainly on male-phase flowers, which are larger than female-phase flowers. Poppies that contain beetles are larger than the population average. These findings support the hypothesis that males and females meet by orienting to large red displays. Corolla size correlates with pollen reward in both plant species, suggesting that visits to large flowers also yield foraging benefits. Male beetles often jump rapidly among adjacent flowers. By contrast to the preference for large flowers by stationary individuals, these jump sequences are random with respect to flower sex-phase (in anemone) and size (in poppy). They may enable males to detect females at close range. We hypothesize that males employ a mixed mate-searching strategy, combining orientation to floral signals and to female-produced cues. The glaphyrids' preference for large flowers may have selected for extraordinarily large displays within the 'red anemone' pollination guild of the Levant.
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