Individual quality and reproductive performance in the Grey-headed Albatross Diomedea chrysostoma

The reproductive performances of Grey-headed Albatrosses Diomedea chrysostoma with a previous record (≤5 years) of consistent success (≤70% chicks fledged from eggs laid—"top" birds) or failure (≤ 70% of attempts failed—"bottom" birds) were compared during 1993 -1995. In 1995, top birds arrived back at the colony significantly earlier, had significantly shorter first and second incubation shifts and hatched larger chicks which grew significantly faster than bottom birds. In 1994, top birds also had larger hatchlings with higher rates of growth than bottom birds. In 1994, top birds had significantly higher hatching, fledging and therefore overall breeding success than bottom birds; very similar trends were evident in 1993 and 1995. Chick-rearing success and all indices of chick growth suggested that food availability was high in 1995 (and 1993) and low in 1994. Therefore the superior performance of top birds was maintained in years of very different conditions, with the chick-rearing period particularly critical. A simple model (using published demographic parameters for Grey-headed Albatrosses on South Georgia) suggests that top birds would produce 2.5 more chicks over their lifetime than bottom birds. With the currently declining population numbers, the relative contribution of top birds to the next generation may be even greater than this.     

Foraging energetics of Grey-headed Albatrosses Diotnedea chrysostoma at Bird Island,South Georgia

At-sea metabolism (CO₂ production) and water turnover of six breeding Grey-headed Albatrosses Diomedea chrysostoma were measured, using the doubly labelled water method, at Bird Island, South Georgia, Mean food consumption (estimated from a water influx rate of 1.01 1 d^-1 and data on dietary composition) was 1200gd^-1 or 50.4 W. At-sea metabolism (derived from a rate of CO₂ production of 3.98 1 h^-1) was 27.7 W, 2.5 times the estimated basal metabolic rate (BMR). On average the birds ingested nearly twice as much food energy as they expended to obtain it. The metabolic rate during flight (estimated from at-sea metabolism and activity budget data) was 36.3 W (range 34.7–39.0 W) or 3.2 (range 3.0–3.4) times the predicted BMR. This is the lowest cost of flight yet measured, but consistent with the highly developed adaptations for economic flight shown by albatrosses. These results are briefly compared with data for other polar vertebrates (penguins, fur seals) exploiting similar prey.     

Response of terrestrial carbon uptake to climate interannual variability in China

The interest in national terrestrial ecosystem carbon budgets has been increasing because the Kyoto Protocol has included some terrestrial carbon sinks in a legally binding framework for controlling greenhouse gases emissions. Accurate quantification of the terrestrial carbon sink must account the interannual variations associated with climate variability and change. This study used a process‐based biogeochemical model and a remote sensing‐based production efficiency model to estimate the variations in net primary production (NPP), soil heterotrophic respiration (HR), and net ecosystem production (NEP) caused by climate variability and atmospheric CO₂ increases in China during the period 1981–2000. The results show that China's terrestrial NPP varied between 2.86 and 3.37 Gt C yr^?1 with a growth rate of 0.32% year^?1 and HR varied between 2.89 and 3.21 Gt C yr^?1 with a growth rate of 0.40% year^?1 in the period 1981–1998. Whereas the increases in HR were related mainly to warming, the increases in NPP were attributed to increases in precipitation and atmospheric CO₂. Net ecosystem production (NEP) varied between ?0.32 and 0.25 Gt C yr^?1 with a mean value of 0.07 Gt C yr^?1, leading to carbon accumulation of 0.79 Gt in vegetation and 0.43 Gt in soils during the period. To the interannual variations in NEP changes in NPP contributed more than HR in arid northern China but less in moist southern China. NEP had no a statistically significant trend, but the mean annual NEP for the 1990s was lower than for the 1980s as the increases in NEP in southern China were offset by the decreases in northern China. These estimates indicate that China's terrestrial ecosystems were taking up carbon but the capacity was undermined by the ongoing climate change. The estimated NEP related to climate variation and atmospheric CO₂ increases may account for from 40 to 80% to the total terrestrial carbon sink in China.