Identification and breeding biology of the diving petrels Pelecanoides georgicus and P. urinatrix exsul at South Georgia

Abstract

The biology of two species of diving petrel (Pelecanoides georgicus and P. urinatrix exsul) was studied at Bird Island, South Georgia. Existing criteria (bill shape and morphology, wing length) for distinguishing these species are reviewed, and several new characters are recognised. For adults bill depth, the colour of the posterior part of the tarsus, and vocalisations are distinctive; chicks have down of different colours (pale grey in P. u. exsul, dark grey in P. georgicus). At South Georgia the species breed in different habitats and at different times - P. u. exsul nests in steep tussock slopes in very early summer, P. georgicus in fine scree slopes in midsummer. P. georgicus lays a proportionately larger egg, and has an incubation period of 46 days (c.54 days in P. u. exsul) and a chick fledging period of 46 days. The fledging period of P. u. exsul is 54 days, very similar to recorded values for P. u. urinatrix (53.5 days) and P. u. chathamensis (56 days). Data on feeding frequency and feed size were derived from daily chick weighings and from twice-daily weighing during 30 days preceding fledging. In both species chicks are fed every night, and often by both parents. In P. georgicus true mean chick feed size is c.37 g; in P. u. exsul it may be slightly less. Analysis of chick stomach contents suggests that P. u. exsul feeds extensively on copepods, whereas P. georgicus largely takes krill (Euphausia superba). P. u. exsul breeding adults commence moulting before their chicks have fledged; P. georgicus moults exclusively in the non-breeding season. Ectoparasites were collected, and the feather louse Pelmatocerandra setosa was found to be restricted to P. u. exsul, and Pelmatocerandra enderleini to P. georgicus. P. georgicus, which breeds later and whose chicks fledge faster, is suggested to be better adapted to the climatic and marine environmental conditions than P. u. exsul, which may be the more recent colonist of these high latitudes.     

Diving pattern and performance in the macaroni penguin Eudptes chrysolophus

The pattern and characteristics of diving in two female macaroni penguins Eudyptes chrysolophus was studied, during the brooding period, using continuous-recording time-depth recorders, for a total of I8 days (15 consecutive days) during which the depth, duration and timing of 4876 dives were recorded. Diving in the first 11 days was exclusively diurnal, averaging 244 dives on trips lasting 12 hours. Near the end of the brooding period trips were longer and included diving at night. About half of all trips (except those involving continuous night-time diving) was spent in diving and dive rate averaged 14–25 dives per hour (42 per hour at night). The duration of day time dives varied between trips, and averaged 1.4–1.7 min, with a subsequent surface interval of 0.5–0.9 min. Dive duration was significantly directly related to depth, the latter accounting for 53% of the variation. The average depths of daytime dives were 20–35 m (maximum depth 11 5 m). Dives at night were shorter (average duration 0.9 min) and much shallower (maximum 11 m); depth accounted for only 6% of the variation in duration. Estimates of potential prey capture rates (3–5 krill per dive; one krill every 17–20 s) are made. Daily weight changes in chicks were directly related to number of dives, but not to foraging trip duration nor time spent diving. Of the other species at the same site which live by diving to catch krill, gentoo penguins forage exclusively diurnally, making longer. deeper dives; Antarctic fur seals, which dive to similar depths as macaroni penguins, do so mainly at night.     

Stable isotope evidence of diverse species-specific and individual wintering strategies in seabirds

Although there is increasing evidence that climatic variations during the non-breeding season shape population dynamics of seabirds, most aspects of their winter distribution and ecology remain essentially unknown. We used stable isotope signatures in feathers to infer and compare the moulting (wintering) habitat of subantarctic petrels breeding at two distant localities (South Georgia and Kerguelen). Petrels showed species-specific wintering habitat preferences, with a similar pattern of latitudinal segregation for all but one taxon. At both localities, delta13C values indicated that blue petrels (Halobaena caerulea) moult in Antarctic waters, South Georgian diving petrels (Pelecanoides georgicus) in the vicinity of the archipelagos and/or in the Polar Frontal Zone and Antarctic prions (Pachyptila desolata) in warmer waters. In contrast, common diving petrels (Pelecanoides urinatrix) showed divergent strategies, with low and high intrapopulation variation at South Georgia and Kerguelen, respectively. Birds from Kerguelen dispersed over a much wider range of habitats, from coastal to oceanic waters and from Antarctica to the subtropics, whereas those from South Georgia wintered mainly in waters around the archipelago. This study is the first to show such striking between-population heterogeneity in individual wintering strategies, which could have important implications for likely demographic responses to environmental perturbation.     

The food and feeding ecology of Blue petrel (Halobaena caerulea) and Dove prion (Pachyptila desolata)

The diet of two small burrow dwelling petrels, Dove prion, Pachyptila desolata and Blue petrel Halobaena caerulea , was studied at the subantarctic island of South Georgia by quantitative analysis of 246 food samples regurgitated by adults about to feed chicks. Crustaceans, and particularly krill Euphausia superba , predominate in both species' diet but fish is considerably more important to the Blue petrel. Other dietary differences between the species chiefly involve the relative proportions of krill, copepods (nearly exclusive to Dove prion) and seven amphipod species taken.
There is no overlap in the species' chick feeding periods but food differences are likely to reflect prey selection rather than resource availability; differences in prey size are ascribed to use of different feeding techniques particularly relating to bill structure and function. Data on frequency of chick feeding, proportion of oil and presence of pumice in food samples are used to indicate that the Blue petrel feeds further away from the breeding colony than the Dove prion. The significance of the various adaptive differences is discussed.     

Regulation of parental investment in the Antarctic petrel Thalassoica antarctica: an exchange experiment

An experiment was conducted on the Antarctic petrel to test whether the parents were able to respond to changes in food demand of their offspring. Two experimental groups were formed by replacing eight 20-day-old chicks with 10-day-old chicks, and vice versa. The growth rate of chicks in the experimental groups was compared with that in two control groups with chicks of known age. The growth rate of 10-day-old chicks in the nests of parents which initially had 20-day-old chicks did not differ significantly from that in their respective control groups. This indicates that those parents were able to raise a new young nestling, despite having already raised another chick from hatching to 20 days. However, the 20-day-old chicks placed in nests with 10-day-old chicks had a significantly lower growth rate than their control group. Feeding rate per day and nest did not differ significantly among any of the groups. This suggests that the observed difference in growth rate between 20-day-old chicks is related to a lower amount of food delivered per visit to experimental chicks. Thus, in the Antarctic petrel, the feeding rate apparently is not regulated by the status of the chick, but by the parents' ability to gather food or willingness to provide food for the chicks.Publication no. 137 from the Norwegian Antarctic Research Expedition (NARE) 1989/90     

Neonatally-induced thermotolerance: physiological responses

1. Broiler cockerels exposed to neonatal heat (35-37.8 degrees C for 24 hr) at 5 days of age experienced significantly lower mortality upon exposure to elevated temperatures (35-37.8 degrees C) at 43 days of age than did cockerels not given neonatal heat exposure. 2. No differences were found between neonatally stressed and neonatal control groups in water consumption, core and surface temperature, plasma T3 and T4, protein or glucose concentration when exposed to juvenile heat stress. 3. Heterophil to lymphocyte ratios were significantly lower in the neonatally stressed than in the neonatal control group when exposed to heat at 44 days of age. 4. The results indicate that lower mortality during periods of high environmental temperature in the neonatally stressed chicks may involve homeostatic mechanisms different from those utilized during acclimation to high environmental temperature.     

Food and feeding ecology of Wilson's storm petrel Oceanites oceanicus at South Georgia

At South Georgia, the diet of Wilson's storm petrel was studied using the regurgitates of adults arriving to feed chicks. Feeding frequency and meal size were estimated by weighing chicks twice daily, or in some cases every 3 h during daytime. Crustaceans contributed 98% of the total number of individual items and 68% of the total weight consumed; fish, 1% of the number of items and 28% of the weight. The most abundant crustacean was the amphipod Themisto gaudichaudii, which accounted for 90% of the total number but only 44% of the total weight of crustaceans eaten. Most (79%) of the Themisto were juveniles. Euphausiids were much less numerous in the diet (5% by number) but were the main group by weight (55%); most (52%) were Antarctic krill, with juveniles and sub-adults (25–50 mm long) predominating. Mysids, copepods and barnacle larvae were also present. Fish were all myctophids (lanternfish), Protomyctophum normani and P. bolini being identified; specimens were 50–85 mm long and weighed 1–4 g. Meal sizes averaged 6-5-7-5 g (14–22% adult body mass); about 75% of chicks were fed each day (mainly at night), about 10% probably receiving meals from both parents. A review of storm petrel diets emphasizes the importance of fish to Oceanodroma species and of crustaceans to Oceanites, Garrodia and Pelagodroma. Euphausiids and amphipods (chiefly Themisto and Hyperia) are the main crustacean prey and range from 5–50 mm and 0-005-0-7 g. Myctophids are the main fish prey and range from 20–100 mm and 1–5 g. Meal size ranges from 15–25% adult body mass and chicks are fed on 50–85% of days. This low delivery rate is mainly responsible for the disproportionately slow growth and long fledging period of storm petrel chicks.     

Stressor-associated alterations in porcine plasma prolactin

Experiments were conducted to determine effects of restraint and thermal stressors on plasma prolactin (PRL) in castrated male pigs. A single 20-min restraining period in a restraining cage which prevented both movement and injury increased (P less than 0.05) plasma PRL when applied at either 0800 or 1600 hr. Exposure to 32 degrees C at 0800-1000 hr or at 1600-1800 hr produced more moderate increases (P less than 0.05). A combination of 20 min restraint and 2 hr at 32 degrees C produced a response similar to restraint alone. Twenty minutes after stressor application plasma PRL concentrations in pigs exposed to restraint or restraint +32 degrees C at 1600 h were greater (P less than 0.05) than concentrations measured in all other treatment groups at that time interval. However, there were no statistically significant differences in additional quantitative indices of the plasma PRL responses (maximal level, maximal change, or integrated response above basal levels) among restraint, 32 degrees C, or restraint +32 degrees C, nor between morning and afternoon applications of treatment. Such data do not provide, therefore, any strong evidence for stressor-dependent or circadian differences in plasma PRL response. A second study subjected castrated male pigs to 20 degrees C (controls), 20 +/- 12 degrees C (cyclic temperature, sine wave variation), 5 degrees C constant, and 5 +/- 12 degrees C cyclic for 20 days. After 6 days exposure to 5 degrees C constant or 5 +/- 12 degrees C cyclic there were decreases (P less than 0.05) of 59 and 67% respectively in plasma PRL when compared either with pretreatment levels or with levels in pigs at 20 or 20 +/- 12 degrees C. There were no differences in PRL responses between cyclic vs constant temperatures. These results are the first to indicate that plasma PRL in pigs is affected by acute restraint and thermal stressors.     

Effects of meal-time feeding and protein restriction on walking ability and some bone and carcass properties in broilers

This experiment was designed to investigate the effects of meal-time feeding and protein restriction on performance, gait score (GS) and carcass and bone traits in broilers. A total of 420 1-day-old chicks were wing banded and randomly distributed into 21 pens with 20 chicks each. At 7 days of age, chicks were weighed and randomly assigned to one of the three treatments: (1) control (C) feed (23.02% crude protein (CP)) was available ad libitum; (2) meal-time feeding (MF); control feed was available from 0100 to 0900 h and from 1500 to 2300 h. Food was withdrawn from 0900 to 1500 h and whole wheat (10 g/bird per day) was dispersed on the floor from 7 to 21 days; and (3) low-protein (LP) diet (19.71% CP) was fed to the chicks from 7 to 21 days. All of the groups were fed ad libitum from 1 to 7 days of age and from 21 to 45 days of age with a standard commercial diet. Individual body weight was measured on days 7, 21 and 45. Feed consumption was measured from 7 to 21 days and from 21 to 45 days. Forty-two chicks were humanly slaughtered and eviscerated for bone evaluation, on days 21 and 45. Also carcass characteristics were determined on day 45. Control group body weight was significantly higher (P < 0.05) at 21 and 45 days of age than the MF and LP groups, which did not differ. Feed intake was reduced by meal-time feeding and LP diet (P < 0.01). Feed efficiency was the best in the MF group during the period of 21 to 45 days of age (P < 0.01). In the control group, shank was significantly longer than that of the LP group and tibia breaking strength was higher than that of the MF group at 21 days (P < 0.05). However, shank width, tibia wet weight and tibia mid-diaphysis ash percentage of the MF group were significantly lower than those of the C and LP groups at 21 days of age (P < 0.05). GS, shank and carcass and tibia bone traits on day 45 were not significant among groups. No compensatory growth and walking ability improvement were observed at 45 days of age for broilers fed with MF and LP between 7 and 21 days of age.     

Thermoregulation in Antarctic fulmarine petrels

We measured resting metabolic rates at air temperatures between ca. −5 and 30 °C in snow petrels (Pagodroma nivea), cape petrels (Daption capense), Antarctic petrels (Thalassoica antarctica), and Antarctic fulmars (Fulmarus glacialoides). We measured seven age classes for each species: adults, and nestlings that were 3, 8, 15, 28, 35, and 42 days old. Basal metabolic rate (BMR) and thermal conductance (C) of adults averaged, respectively, 140% and 100% of values predicted allometrically for nonpasserine birds. Minimum metabolic rates of unfasted nestlings aged 15–42 days averaged, respectively, 97% and 98% of predicted adult BMR in Antarctic petrels and snow petrels, versus 119% and 126% of predicted in Antarctic fulmars and cape petrels. Nestlings of the southerly breeding snow petrel and Antarctic petrel were relatively well insulated compared with nestlings of other high-latitude seabirds. Adult lower critical temperature (T_lc) was inversely related to body mass and averaged 9 °C lower than predicted allometrically. As nestlings grew, their T_lc decreased with increasing body mass from ca. 14 to 22 °C (depending upon species) at 3 days of age, to −4 to 8 °C when nestlings attained peak mass. Nestling T_lc subsequently increased as body mass decreased during pre-fledging weight recession. Nestling T_lc was close to mean air temperature from the end of brooding until fledging in the three surface nesting species. Accepted: 12 July 2000     

The development of endothermy during pouch life in the eastern barred bandicoot (Perameles gunnii), a marsupial

Marsupials are born ectothermic and gradually become endothermic during pouch occupancy. In order to study the timing of this transition, we measured the metabolic rates of eight pouch-young eastern barred bandicoots (Perameles gunnii) at 25 degrees C (the thermoneutral zone of adults), at 35 degrees C (pouch temperature), and after injection with norepinephrine. From 5 to 7 wk of age, oxygen consumption (VO(2)) was higher at 35 degrees C than at 25 degrees C. At 8 wk, VO(2) was significantly higher at 25 degrees C than at 35 degrees C. Norepinephrine administration at 5 and 6 wk had no effect on metabolic rate, but at 8 wk, near pouch vacation, it resulted in a significant increase in metabolic rate. Our results indicate that signs of thermoregulation for P. gunnii begin at 7 wk, and at 8 wk the species is endothermic, that is, able to increase heat production in response to both cold and norepinephrine. The appearance of fur, first seen at the age of 6 wk and fully developed at 8 wk, coincides with the onset of endothermy.     

Anaerobic wintering of crucian carp (Carassius carassius L.)--II. Metabolic products

In long-term experimental anoxia (up to 140 days) crucian carp excreted ethanol and acetic acid. The maximum concentration of ethanol found in fish blood was ca 0.1%. The excretion rate of ethanol at temperatures from -0.5 to +5 degrees C was ca 25 micrograms/g fish wet wt/hr, but increased rapidly with increasing temperature. At 2 and 5 degrees C the ethanol excretion rate was independent of fish size, but at 12 and 18 degrees C a higher rate was observed in smaller fish. The decrease of water pH below 5 in the experimental vial during long anoxia was assumed to be due to excretion of acid compounds by the fish.     

Prophylactic and therapeutic studies on intestinal giant-cystic disease of the Israel carp caused by Thelohanellus kitauei. II. Effects of physical and chemical factors on T. kitauei spores in vitro

In a basic attempt to develop the prophylactic and therapeutic measures on intestinal giant-cystic disease of the Israel carp, Cyprinus carpio nudus, the effects of physical and chemical factors on viability or survival of the spores of Thelohanellus kitauei were checked in vitro by means of extrusion test on the polar filament. When the fresh spores suspended with 0.45% and 0.9% sodium chloride solution and distilled water were laid at 5 degrees C and 28 degrees C for short terms, the extrusion rates increased until the 3rd day, meanwhile when some of them were suspended with Tyrode's solution at -70 degrees C the rates increased gradually until the 8th day. Viabilities of the spores suspended with 0.9% saline and added antibiotics to the suspension at 5 degrees C for long terms lasted for 997 days and 1,256 days (presumed values) at maximum, respectively. The spores suspended with distilled water at 28 degrees C for long terms survived 152.4 days, but the spores suspended with Tyrode's solution at -70 degrees C for long terms showed almost the same viable pattern as early freezing stages up to 780 days. The spores suspended with Tyrode's solution, frozen at -70 degrees C and thawed at 5 degrees C, showed the highest rate of extrusion of the polar filament. In the case of frozen spores, the extrusion rates during heating tend to become higher in accordance with the increase of frozen period, and the critical points of 180 day-frozen spores to be killed were generally 78.5 hr. at 60 degrees C, 23.4 hr. at 70 degrees C, 189.1 min. at 80 degrees C or 10.5 min. at 90 degrees C. The longer the spores were frozen, the more time was needed for the death of spores after thawing; 20 days-17.4 days, 100 days-33.2 days, and 400 days-37.8 days. The longer the spores were frozen, the more time was needed for the death of spores at a conventional when they were dried air drying condition, 540 days-23.5 days, 160 days-21.0 days, and 20 days-14.4 days. On the other hand, the longer the spores were frozen, the more spores were dead rapidly when they were irradiated with 10W UV-ray; 100 days-26.0 hr, 300 days-21.9 hr, and 540 days-13.9 hr. The time needed for killing 200 days-frozen spores by various disinfectants at 1,000 ppm was 5.2 min. by calcium oxide, 10.4 min. by potassium permanganate, 27.8 min. by malachite green and 14.3 hr. by formalin.(ABSTRACT TRUNCATED AT 400 WORDS)     

An experimental test of the thermoregulatory hypothesis for the evolution of endothermy

The thermoregulatory hypothesis proposes that endothermy in mammals and birds evolved as a thermoregulatory mechanism per se and that natural selection operated directly to increase body temperature and thermal stability through increments in resting metabolic rate. We experimentally tested this hypothesis by measuring the thermoregulatory consequences of increased metabolic rate in resting lizards (Varanus exanthematicus). A large metabolic increment was induced by feeding the animals and consequent changes in metabolic rate and body temperature were monitored. Although metabolic rate tripled at 32 degrees C and quadrupled at 35 degrees C, body temperature rose only about 0.5 degrees C. The rate of decline of body temperature in a colder environment did not decrease as metabolic rate increased. Thus, increasing the visceral metabolic rate of this ectothermic lizard established neither consequential endothermy nor homeothermy. These results are inconsistent with a thermoregulatory explanation for the evolution of endothermy.     

Comparative growth and development of the metacercariae of Fibricola seoulensis (Trematoda: Diplostomidae) in vitro, in vivo and on the chick chorioallantois

The growth and development of the metacercariae of F. seoulensis cultivated in vitro or on the chick chorioallantois were assessed by comparison with the optimum process of maturation in albino rats and new born chickens. The process of maturation was divided for convenience into six stages: Stage 1; cell multiplication, Stage 2; body shaping, Stage 3; separation of genital anlagen, Stage 4; organogeny, Stage 5; gametogony, and Stage 6; oviposition. In Hank's and Tyrode's solutions, the metacercariae were alive up to 200 days or more at 4 degrees C without any development. The in vivo maturation process in rats or chicks was as follows: stage 1 from 6 hours; stage 2 from 24 hours; stage 3 from 48 to 72 hours; stage 4 from 3 to 4 days; stage 5 from 4 to 5 days; and stage 6 from 5 to 8 days. Despite unsuccessful infection of the metacercariae to 12 day old chicks, fully mature worms of stage 5 or 6 were recovered from new born chicks (1 to 2 days old). The metacercariae of F. seoulensis grown in vitro were up to stage 3 and no further maturation was observed. Of various media employed, the medium NCTC 109 (Gibco) or NCTC 135 (Gibco) supplemented with 20% egg yolk or 20% whole egg macerate or 0.5% yeast was basically required for the earlier development of the fluke. It took 16.1 days (in average) to reach the stage 3 after cultivation. The metacercariae cultivated on the chorioallantoic membranes of 6-13 day old chick embryo at 37-38 degrees C showed their full development up to stage 5 or 6. However, the worms were in general remarkably retarded, compared with those grown in rats or chickens. In the experiments of worm transplant, although the transfer was failed from in vitro culture to in vivo of rats (per os), the transplants from in vitro culture to the chorioallantois and from the chorioallantois to in vivo of rat host were successful with or without development of the transferred worms. In the present study, it was observed that the metacercariae of F. seoulensis can be maintained in vitro media with poor development as well as fully matured in 1 to 2 day-old chicks or on the chorioallantois at a very low rate.     

Growth, fledging success and post-fledging survival of juvenile Oystercatchers Haematopus ostralegus

We studied the consequences of differences in growth rate on the subsequent survival of Oystercatcher Haematopus ostralegus chicks. Fledging success increased sharply with growth rate, from zero in chicks growing at less than 6 g per day to about 85% in chicks growing at more than 10 g per day. The age at which chicks fledged varied from 27 to 52 days. Chicks which fledged at an early age displayed a much faster growth rate than later fledging chicks. Although slow growth resulted in a considerable prolongation of the period before fledging, slow-growing chicks fledged at a smaller size and with a lower body-weight than fast-growing chicks. After fledging, all chicks remained almost completely dependent on their parents up to an age of 3 months and often longer.
Almost 40% of the fledglings eventually returned to the breeding area. This figure probably reflects post-fledging survival. Age and size at fledging had no effect on a chick's probability of return. Body-weight at fledging had a small positive correlation with the return probability, but this was not statistically significant. We conclude that although slow growth severely reduces a chick's chance of fledging, it probably does not result in irreversible damage causing an increased risk of mortality during the first years after fledging. Apparently, any possible disadvantage associated with small size or low body-weight could be compensated for after fledging.     

Thyroid hormone response to thyrotropin releasing hormone after cold treatment during pre- and postnatal development in the domestic fowl

The purpose of the present study was to compare the effect of periodic cooling during the establishment of a functional pituitary-thyroid axis at days 11-14 of incubation and at other developmental stages, on the subsequent thyroid hormone response to thyrotropin releasing hormone (TRH). In the first and second experiment chick embryos were cooled for 6 hr/day to 30 degrees C from day 11 till 14 and from day 15 till 18 respectively, whereas control groups were incubated throughout at 37.8 degrees C. In both experiments the thyroxine (T4) response upon TRH in 19 day-old embryos was higher in the previously cold treated embryos, according to the percentages of increase. However, the higher T4 response in the cold treated animals disappeared in 1 or 7 day-old chicks hatched from the 2nd experiment, but remained present in chicks of the same ages in the 1st experiment. In a third experiment the T4 response to TRH injection immediately and 3 and 8 days after a temperature treatment (25 degrees C or 12 degrees C) for one week on four weeks old broiler chickens was found to be similar in both temperature groups. In all experiments there was a concomitant triiodothyronine (T3) increase after TRH injection, but differences between experimental groups were observed at days 15 and 19 of incubation and immediately after the postnatal temperature treatment. As an overall conclusion the results indicate that cold treatment only during the establishment of the hypothalamo-hypophysial control of thyroid function can have a long lasting effect by enhancing the T4 response to TRH injection.     

The relationship between rate of oxygen consumption, heart rate and thermal conductance of the dik-dik antelope (Rhynchotragus kirkii) at various ambient temperatures

1. The extent of cardiovascular adjustments to heat and cold were investigated between ambient temperatures of 5 and 45 degrees C by measuring conductance and the rates of oxygen consumption and heart beats. 2. Minimum heart rate was observed at 25 degrees C (114 +/- 9 beats/min). In the heat at 45 degrees C heart rate was observed to increase only slightly (127 +/- 12 beats/min) but in the cold -5 degrees C heart rate nearly doubled that at 25 degrees C. 3. Thermal conductance was on average 0.031 mlO2 (g. hr. degrees C)-1 below 25 degrees C but increased by more than 20 times at 40 degrees C. 4. A positive correlation between heart rate and rate of oxygen consumption was demonstrated below 25 degrees C and the relation may be of practical use.     

On mechanisms of removing astringency in persimmon fruits by carbon dioxide treatment I. Some properties of the two processes in the de-astringency

Carbon dioxide treatment of persimmon fruit (Diospyros KakiL., cv. "Hiratanenashi" astringent type) at 20?C for 24 hr,at 30?C for 12 hr, or at 40?C for 6 hr followed by storage inair at 30?C for 3 days produced de-astringent fruit of excellentquality without abnormal softening. The induction process inthe anaerobic atmosphere had a Q₁₀ of ca. 2.0 and the subsequentde-astringency process, which proceeded either in air or carbondioxide, had Q₁₀ of ca. 1.4. During the short gas treatment(at 40?C for 6 hr) the ethanol content increased rapidly andreached a maximum of 28.0 mg and the acetaldehyde content graduallyreached 0.443 mg per fruit, whereas the soluble tannin(s) contentdecreased rapidly to two-thirds of its initial level. Therewas a lag period of 3 hr in the decrease of soluble tannin(s).Dimedon and sodium bisulfite, as well as sodium fluoride, inhibitedde-astringency. The mechanisms of removing astringency in thisfruit are discussed. (Received June 3, 1976; )     

Diving behaviour of white-chinned petrels and its relevance for mitigating longline bycatch

The white-chinned petrel (Procellaria aequinoctialis) is the seabird species most commonly killed by Southern Hemisphere longline fisheries. Despite the importance of diving ability for mitigating longline bycatch, little is known of this species’ diving behaviour. We obtained data from temperature–depth recorders from nine white-chinned petrels breeding on Marion Island, southwestern Indian Ocean, during the late incubation and chick-rearing period. Maximum dive depth (16 m) was slightly deeper than the previous estimate (13 m), but varied considerably among individuals (range 2–16 m). Males dived deeper than females, and birds feeding chicks dived deeper than incubating birds, but dive rate did not differ between the sexes. Time of day had no significant effect on dive depth or rate. Our findings will help to improve the design and performance of mitigation measures aimed at reducing seabird bycatch in longline fisheries, such as the calculation of minimum line sink rates and optimum aerial coverage of bird-scaring lines.