Sperm whales Physeter macrocephalus were observed off the Galapagos Islands between late February and April 1985, a year of cool sea-surface temperatures (SST), and January to June 1987, an 'El Nino' year of warm SST Distributlon, abundance and diet of sperm whales were similar in both years. However, in 1987 they appeared to have a lower feeding success, as ind~cated by a reduced rate of observing faeces, and dived to shallower depths. Excretion rates were negatively correlated with sea-surface temperatures.The 'El Nino' phenomenon, an irregular event in which exceptionally warm surface waters appear in the central and eastern tropical Pacific, has considerable effects on most marine life in the area (Merlen 1984, Arntz 1986, Barber & Chavez 1986). El Nido is unfavourable to most pelagic species, but there is little information concerning its effects on mesopelagic species, largely because organisms in this depth range are hard to sample for biomass.The sperm whale Physeter macrocephalus, which feeds in this ecosystem, has indirectly provided considerable information on mesopelagic squid through studies of stomach contents and diving behaviour (Clarke 1980). Recently, research on living sperm whales has also given results on sperm whale feeding behaviour and the ecosystems in which they feed (Gordon 1987, Papastavrou 1987.In this note we relate indications of the feeding success of sperm whales around the Galapagos Islands to sea-surface temperature. We principally use data collected in 1985, a year of cool sea-surface temperatures (mean SST in early 1985 near Galapagos = 25.4 "C), and 1987, an 'El Nilio' year (mean SST in early 1987 near Galapagos = 27.5 "C). We also summarize results on differences and similarities in the distribution, abundance and behaviour of the whales between the 2 years. The rate of observing faeces was used as an indicator of the feeding success of the whales. For this measure we only used faeces observed as the whales fluked-up at the start of a feeding dive, and calculated the proportion of fluke-ups observed within 250 m of the research vessel which were accompanied by a defaecation. This meant that defaecations during breaches (leaps from the water) and other energetic acitivity were not included. Such defaecations may be more related to physiology than feeding success. A total of 3921 fluke-ups were observed within 250 m of the research vessel, and of these 125 were accompanied by defaecations. Sea-surface temperatures were measured every 3 h, but only 06:OO h readings are used in this paper, to avoid the effects of the warming of the surface layer by the sun. Rates of observing faeces and mean sea surface temperatures were calculated for each calendar month while in the Galapagos.The rate at which we observed faeces was significantly, = 21.96, p < 0.01) higher in 1985 (4.8 % of fluke-ups observed with faeces) than in 1987 (2.1 % of fluke-ups observed with faeces). The rate of seeing faeces during each month was negatively correlated with the mean 06:OO h SST during tha...
Reproductive events related to time of breeding and fecundity among species of New Guinean Rattus are examined relative to latitude, altitude, and possible climatological cues. At least half of the 25 subspecies examined can breed in any month, and this capability appears to be unrelated to annual photoperiod fluctuations and ambient temperature at different altitudes. Both rainfall and commensalism may exert strong influence on local breeding regimes. This, the first reproductive analysis of all New Guinean species of this genus, permits comparison with similar events in Australian Rattus, and generalised patterns of breeding in these Australasian species are proposed.
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