Eleven polymorphic microsatellite markers in Cory's shearwater, Calonectris diomedea, and cross-species amplification on threatened Procellariiformes

For the first time, we describe 11 variable dinucleotide microsatellites and the conditions for multiplexing and simultaneous genotyping sets of loci in Cory's shearwater, Calonectris diomedea. Microsatellite variability was assessed in a colony from the Azores archipelago (Atlantic Ocean). Two to eight alleles were detected per locus, the mean gene diversity being 4.5. Cross-species amplification in three other seabirds (Diomedea exulans, Procellaria aequinoctialis and Bulweria bulwerii) revealed some variability at one, two and eight loci, respectively.     

Responses of breeding Cory's shearwater Calonectris diomedea to experimental manipulation of chick condition

We studied the regulation of provisioning in Cory's shearwaterat Selvagem Grande during the chick rearing period. Provisioningwas examined in terms of feeding frequency and amount of fooddelivered to chicks. Two groups of chicks were subjected toshort-term contrasting manipulations of their nutritional status:one group of chicks was given a food supplement of about 30g, and another group was deprived of up to 30 g of food. Adultstending deprived chicks increased the frequency of feedingvisits (but not the size of feeds), which resulted in an increasein the net rate of food delivery. At the end of this study,deprived chicks were growing at the same rate as fed chicks. Parents attending fed chick did not change their provisioningrates in response to the treatment. Our results indicate thatCory's shearwaters are able to adjust their provisioning ratein response to short-term variation in the nutritional statusof their chicks. We also examined the change in the beggingrate of fed and deprived chicks in response to the treatment.There was no relationship between the begging rate and thecondition of chicks, which is taken to be a measure of thechick's physiological condition, related to its ability towithstand imposed periods of fasting. However, fed chicks decreasedtheir begging rate after the increase in their condition dueto supplementary food. Conversely, deprived chicks, which wereonly able to sustain their condition before the onset of thetreatment, maintained high levels of begging. To some extent,these results suggest that parental provisioning can be influencedby the begging behavior of chicks.     

Chick‐provisioning behaviour of two shearwaters breeding in south‐eastern Australia

The chick‐provisioning behaviour of the short‐tailed shearwater Puffinus tenuirostris and the wedge‐tailed shearwater Puffinus pacificus was investigated in a mixed colony on Montague Island, New South Wales, Australia, over two breeding seasons. This colony is located at opposite edges of the breeding distribution of the two species. Frequent weighing techniques were used to determine chick feeding frequency, feed timing, meal size, chick weight loss and indices of food conversion efficiency of the chicks. Short‐tailed shearwater parents fed their chicks larger more infrequent meals than wedge‐tailed shearwater parents. Short‐tailed shearwater chicks demonstrated higher food conversion efficiencies and lower weight loss than wedge‐tailed shearwater chicks, indicating either differences in diet or metabolic rates. The feeding frequency in wedge‐tailed shearwaters also fluctuated more widely than for short‐tailed shearwaters over the two breeding seasons. Despite the fact that the timing of the breeding cycle on Montague Island is almost identical for the two species, these differences in chick provisioning are probably a result of differences in prey type and location, so they may help explain variations in annual breeding success and limits to the distribution of the two species.     

Crop size as an index of chick provisioning in the Greater Flamingo Phoenicopterus roseus

After being fed by their parents, Greater Flamingo chicks store food in their crops, which protrude outwards. We allocated the crop profiles of chicks to four categories to assess the relationship between body mass and crop profile variation, and so determine whether crop size can be used as an accurate index of the amount of food ingested, and to determine the timing and frequency of provisioning. We registered changes in body mass and crop fullness in eight chicks captured with turgid crops and kept in captivity until constant mass was achieved. The meal mass ingested by the chicks during each parental feeding was around 18% of net chick mass and varied greatly with crop profile. Mean transition times between the four crop profile categories ranged from 6 to 14 h. Between 1998 and 2009, 34% of chicks caught for ringing in a breeding colony had empty crops. From crop profiles recorded during the handling of chicks, it was estimated that approximately one‐third of the chicks were fed in the evening and another third during the night. Our results have implications for the estimation of body condition indexes because body mass should be free of the influence of the mass of the food in the crop.     

Foraging and provisioning strategies of black-browed albatrosses in relation to the requirements of the chick: natural variation and experimental study

We studied regulation of the food supply to black-browed albatrosschicks at Kerguelen by simultaneously recording the provisioningrates achieved by individual parents and satellite trackingforaging birds during two seasons, by studying changes in adultmass, and by experimentally manipulating the food requirementof chicks. In 1994 black-browed albatrosses had a higher breedingsuccess and produced heavier chicks that grew faster than in1995. They spent a similar time foraging but brought heaviermeals to their chick in 1994. Satellite tracking indicated thatin both seasons birds foraged in the same oceanographic area,250 km from the colony. Travel times to and from this area remainedunchanged, and similar times were spent foraging there. In ourstudy area, black-browed albatrosses appear to rely on a foodresource that is predictable in location, but whose availabilityvaries from one year to the next. The principal difference betweenyears of differing food availability was that birds broughtlarger meals when food was more abundant Costs of commutingto nearby feeding areas are probably low and allow the deliveryof energy to the chick at a high rate. A study carried out in1991 indicated that there was no relationship between the changesin adult mass from one trip to the next and the duration offoraging trips or feed mass, suggesting that adult body conditionhad little influence on the provisioning strategy of this species.An experiment whereby some chicks were deprived of food andothers received supplementary food showed that parents of underfedchicks spent the same time foraging and brought slightly largeramounts of food to their chicks as control parents. We suggestthat parents are searching for food to the maximum limits oftheir ability and thus cannot reduce further foraging time,but underfed chicks can swallow more food. Parents of overfedchicks delivered less food and increased the time between feeds.The reduction in provisioning frequency is interpreted as thecapacity of parents to modify their foraging behavior accordingto the nutritional status of the chick, but the reduction offeed mass is probably the result of chicks being close to theirmaximum assimilatory capacity. Comparison between Procellariiformspecies indicates extensive differences in the degree to whichparents can regulate the supply of food to their chicks. Neriticspecies like black-browed albatrosses appear to have a reducedability to regulate, and especially to increase provisioningrates, whereas more pelagic species may have a greater regulationability