Food supplementation as a conservation intervention:A framework and a case of helping threatened shorebirds at a refuelling site

Supplemental feeding to mitigate the effects of food shortages may in some cases provide critical help to species conservation. However, supplemental feeding may have both positive and negative effects on wildlife and the environment. A scientifically designed feeding project helps to achieve conservation targets and reduces adverse effects. Here, we summarize a three-step framework for food supplementation that we used in practice: (1) determining whether supplemental feeding is required; (2) designing and implementing a practical feeding scheme; and (3) evaluating the effectiveness of food supplementation. We supplemented food for great knots (Calidris tenuirostris), an endangered migratory shorebird, at a recently impoverished refuelling site (Yalu Jiang estuary) in the Yellow Sea in spring 2018. The abundance of the staple food of great knots (Potamocorbula laevis, which had become very rare after 2012), was insufficient for the birds to refuel before the migratory flight to the breeding grounds. In our practical test, living P. laevis were collected in subtidal areas and transported to the intertidal area where great knots had been foraging in earlier years. The supplemented areas attracted 48% of all the great knots present in the 200 km2 study area. Nearly 90% of the supplemented food was consumed. Most great knots (>80%) foraged in the high-density supplementation zone where the densities of P. laevis were restored to the naturally occurring levels in 2011–2012. Here, food intake rates (mg AFDM/s) were 4.2 times those in the adjacent control zones. The framework and the feeding practice should help guide future supplemental feeding in a wide range of species

Individuals of a group-living shorebird show smaller home range overlap when food availability is low

Background: Group living animals, such as shorebirds foraging on intertidal mudflats, may use social information about where to find hidden food items. However, flocking also increases intraspecific competition for resources, which may be exacerbated by food scarcity. Therefore, although aggregation may bring benefits, it may also increase the intensity of intraspecific competition. Methods: We examined this trade-off in adult great knots Calidris tenuirostris, a molluscivorous long-distance migrating shorebird species, using interannual variation based on 2 years with different levels of food availability during their northward migratory staging in the northern Yellow Sea, China. We estimated individual home ranges and the extent of spatial overlap of home ranges of individually tagged birds in 2012 and 2015, whilst discounting for possible differences in body size, body mass, sex and migration schedule between years. Results: We found that home range size was not associated with body mass, arrival date, body size, or sex of the individual. Despite a significant difference in food availability between the two study years, there was no significant change in the 50% and 95% home range size of great knots in the contrasting situations. However, there was a significantly smaller spatial overlap between individuals in the year when food was less available, suggesting that great knots operated more independently when food was scarce than when it was abundant. Conclusions: These results suggest that minimizing intraspecific competition became more important when food was scarce. Where it is impossible to monitor all habitats en route, monitoring the local movements of shorebirds may offer a way to detect changes in habitat quality in real time.</p

Individuals of a group-living shorebird show smaller home range overlap when food availability is low

Background: Group living animals, such as shorebirds foraging on intertidal mudflats, may use social information about where to find hidden food items. However, flocking also increases intraspecific competition for resources, which may be exacerbated by food scarcity. Therefore, although aggregation may bring benefits, it may also increase the intensity of intraspecific competition. Methods: We examined this trade-off in adult great knots Calidris tenuirostris, a molluscivorous long-distance migrating shorebird species, using interannual variation based on 2 years with different levels of food availability during their northward migratory staging in the northern Yellow Sea, China. We estimated individual home ranges and the extent of spatial overlap of home ranges of individually tagged birds in 2012 and 2015, whilst discounting for possible differences in body size, body mass, sex and migration schedule between years. Results: We found that home range size was not associated with body mass, arrival date, body size, or sex of the individual. Despite a significant difference in food availability between the two study years, there was no significant change in the 50% and 95% home range size of great knots in the contrasting situations. However, there was a significantly smaller spatial overlap between individuals in the year when food was less available, suggesting that great knots operated more independently when food was scarce than when it was abundant. Conclusions: These results suggest that minimizing intraspecific competition became more important when food was scarce. Where it is impossible to monitor all habitats en route, monitoring the local movements of shorebirds may offer a way to detect changes in habitat quality in real time.</p

Individuals of a group-living shorebird show smaller home range overlap when food availability is low

Background: Group living animals, such as shorebirds foraging on intertidal mudflats, may use social information about where to find hidden food items. However, flocking also increases intraspecific competition for resources, which may be exacerbated by food scarcity. Therefore, although aggregation may bring benefits, it may also increase the intensity of intraspecific competition. Methods: We examined this trade-off in adult great knots Calidris tenuirostris, a molluscivorous long-distance migrating shorebird species, using interannual variation based on 2 years with different levels of food availability during their northward migratory staging in the northern Yellow Sea, China. We estimated individual home ranges and the extent of spatial overlap of home ranges of individually tagged birds in 2012 and 2015, whilst discounting for possible differences in body size, body mass, sex and migration schedule between years. Results: We found that home range size was not associated with body mass, arrival date, body size, or sex of the individual. Despite a significant difference in food availability between the two study years, there was no significant change in the 50% and 95% home range size of great knots in the contrasting situations. However, there was a significantly smaller spatial overlap between individuals in the year when food was less available, suggesting that great knots operated more independently when food was scarce than when it was abundant. Conclusions: These results suggest that minimizing intraspecific competition became more important when food was scarce. Where it is impossible to monitor all habitats en route, monitoring the local movements of shorebirds may offer a way to detect changes in habitat quality in real time.</p

Individuals of a group-living shorebird show smaller home range overlap when food availability is low

Background: Group living animals, such as shorebirds foraging on intertidal mudflats, may use social information about where to find hidden food items. However, flocking also increases intraspecific competition for resources, which may be exacerbated by food scarcity. Therefore, although aggregation may bring benefits, it may also increase the intensity of intraspecific competition. Methods: We examined this trade-off in adult great knots Calidris tenuirostris, a molluscivorous long-distance migrating shorebird species, using interannual variation based on 2 years with different levels of food availability during their northward migratory staging in the northern Yellow Sea, China. We estimated individual home ranges and the extent of spatial overlap of home ranges of individually tagged birds in 2012 and 2015, whilst discounting for possible differences in body size, body mass, sex and migration schedule between years. Results: We found that home range size was not associated with body mass, arrival date, body size, or sex of the individual. Despite a significant difference in food availability between the two study years, there was no significant change in the 50% and 95% home range size of great knots in the contrasting situations. However, there was a significantly smaller spatial overlap between individuals in the year when food was less available, suggesting that great knots operated more independently when food was scarce than when it was abundant. Conclusions: These results suggest that minimizing intraspecific competition became more important when food was scarce. Where it is impossible to monitor all habitats en route, monitoring the local movements of shorebirds may offer a way to detect changes in habitat quality in real time.</p

The impact of assisted reproductive technology treatments on maternal and offspring outcomes in singleton pregnancies: A review of systematic reviews

Objectives: Assisted reproductive technology (ART) treatments are commonly used to aid conception in subfertile couples. We aimed to evaluate the risks of adverse maternal and offspring outcomes in singleton pregnancy conceived with different ART treatments and techniques. / Evidence review: We searched MEDLINE, EMBASE, CENTRAL and HTA until December 2020 for all systematic reviews evaluating adverse outcomes in pregnancies conceived with various ART techniques, autologous or donor gametes, and embryo development stages. We assessed review quality using the AMSTAR2 tool risk (RR) or odds ratio (OR) with 95% confidence intervals (CI) from the top quality reviews for each of the outcomes of interest across the identified ART treatments and population subgroups. / Results: We included 24 systematic reviews, most reported on observational studies. Compared to spontaneous conception, ART pregnancies had a higher risk of placenta previa (PP) (RR 3.71, 95%CI 2.67-5.16), antepartum haemorrhage (APH) (RR 2.11, 95%CI 1.86-2.38), preterm birth (PTB) (RR 1.71, 95%CI 1.59-1.83), very preterm birth (VPTB) (RR 2.12, 95%CI 1.73-2.59), small for gestational age (SGA) (RR 1.35, 95%CI 1.20-1.52), low birthweight (LBW) (RR 1.61, 95%CI 1.49-1.75) and very low birthweight (VLBW) (RR 2.12, 95%CI 1.84-2.43). Frozen vs fresh embryo transfer was associated with a lower risk for PTB (RR 0.90, 95%CI 0.84-0.97), SGA (RR 0.61, 95%CI 0.56-0.67), LBW (RR 0.72, 95%CI 0.67-0.77) and VLBW (RR 0.76, 95%CI 0.69–0.82). Embryo transfer at blastocyst vs cleavage showed higher risk for PTB (RR 1.10, 95%CI 1.01-1.20) and large for gestational age (LGA) (RR 1.12, 95%CI 1.03-1.21) with lower risk for SGA (RR 0.84, 95%CI 0.76-0.92). Using donor vs autologous oocytes increased the odds of PTB (OR 1.57, 95%CI 1.33-1.86), LBW (OR 1.94, 95%CI 1.10-3.41) and VLBW (OR 1.37, 95%CI 1.22–1.54) as well as maternal complications (postpartum haemorrhage OR 1.96, 95% CI 1.20-3.20, gestational diabetes OR 1.27 95%CI 1.03-1.56, hypertensive disorders of pregnancy OR 2.63, 95%CI 2.17-3.18, and caesarean section OR 2.28, 95%CI 2.14-2.42). / Conclusions: ART treatments are associated with increased risks of adverse maternal and offspring outcomes, especially with donor oocytes. The characteristics of ART treatment should be incorporated into prenatal care planning to mitigate those risks

Individual diet differences in a molluscivore shorebird are associated with the size of body instruments for internal processing rather than for feeding

Especially in birds, it is widely found that the size of individual prey items follows the size of the instruments of prey capture, handling and processing, i.e. bill size. In fact, this is the natural history basis of major discoveries on adaptive evolution in the face of changing food resources. In some birds, e.g. the molluscivore shorebirds ingesting hard-shelled prey, most of the prey processing takes place within the digestive tract. This study of a salvaged sample of actively feeding great knots Calidris tenuirostris accidentally drowned in fishing nets in northern China, is the first documentation of diet selection at the level of the individual in previously well-studied molluscivore shorebirds. Diet composition was not associated with the length of the bill, but with the mass of the muscular gizzard. Gizzard mass, which unlike bill length is a phenotypically flexible trait, enables great knots to adjust to changing food resources as an individual, i.e. instantly responding to the food on offer. For migratory species like great knots which rely on seasonal sequences of interdistant feeding areas offering prey with a variety of characteristics, the capacity to individually adjust appears a key adaptation

Green-house gas mitigation capacity of a small scale rural biogas plant calculations for Bangladesh through a general Life Cycle Assessment approach

Calculations towards determining the greenhouse gas mitigation capacity of a small-scale biogas plant (3.2 m3 plant) using cow dung in Bangladesh are presented. A general life cycle assessment was used, evaluating key parameters (biogas, methane, construction materials and feedstock demands) to determine the net environmental impact. The global warming potential saving through the use of biogas as a cooking fuel is reduced from 0.40 kg CO2 equivalent to 0.064 kg CO2 equivalent per kilogram of dung. Biomethane used for cooking can contribute towards mitigation of global warming. Prior to utilisation of the global warming potential of methane (from 3.2 m3 biogas plant), the global warming potential is 13 t of carbon dioxide equivalent. This reduced to 2 t as a result of complete combustion of methane. The global warming potential saving of a bioenergy plant across a 20-year life cycle is 217 t of carbon dioxide equivalent, which is 11 t per year. The global warming potential of the resultant digestate is zero and from construction materials is less than 1% of total global warming potential. When the biogas is used as a fuel for cooking, the global warming potential will reduce by 83% compare with the traditional wood biomass cooking system. The total 80 MJ of energy that can be produced from a 3.2 m3 anaerobic digestion plant would replace 1.9 t of fuel wood or 632 kg of kerosene currently used annually in Bangladesh. The digestate can also be used as a nutrient rich fertiliser substituting more costly inorganic fertilisers, with no global warming potential impact

Migration timing influences the responses of birds to food shortage at their refuelling site

Because migration is highly time-constrained and migration timing varies among individuals, the responses of migrants to food shortage at a refuelling site could differ between individuals that arrive early and late at the site. To test this hypothesis, we compared the stopover decision, in terms of occurrence and length of stay (LOS), of radiotagged Great Knots Calidris tenuirostris before (2012) and after (2015) a dramatic decline in food supply at a critical spring final pre-breeding refuelling site in the northern Yellow Sea. The probability of occurrence at the refuelling site was consistent between the two\ua0years, whereas the average LOS significantly shortened in the year of food shortage in late-arriving individuals. This suggests migration timing intensifies the influence of food shortage in late-arriving individuals, which might be more sensitive and vulnerable to food shortage at refuelling sites compared with early-arriving individuals