Albatrosses are known to expend only a small amount of energy during flight. The low energy cost of albatross flight has been attributed to energy-efficient gliding (soaring) with sporadic flapping, although little is known about how much time and energy albatrosses expend in flapping versus gliding during cruising flight. Here, we examined the heart rates (used as an instantaneous index of energy expenditure) and flapping activities of free-ranging black-browed albatrosses (Thalassarche melanophrys) to estimate the energy cost of flapping as well as time spent in flapping activities. The heart rate of albatrosses during flight (144 beats min-1) was similar to that while sitting on the water (150 beats min-1). In contrast, heart rate was much higher during takeoff and landing (ca. 200 beats min-1). Heart rate during cruising flight was linearly correlated with the number of wing flaps per minute, suggesting an extra energy burden of flapping. Albatrosses expend only 4.6% ± 1.4% of their time in flapping during cruising flight, which was significantly lower than those during and shortly after takeoff (9.8% ± 3.5%). Flapping activity, which amounted to just 4.6% of the time in flight, accounted for 13.3% of the total energy expenditure during cruising flight. These results support the idea that albatrosses achieve energy-efficient flight by reducing the time spent in flapping activity, which is associated with high energy expenditure.
Twitter released its data relating to the whole of the summer transfer window today and, according to the social network, the move which saw the Premier League champions steal Pedro from under the nose of Manchester United was the most discussed. Bastian Schweinsteiger’s switch from Bayern Munich to Manchester United was second and Raheem Sterling’s move to top-flight leaders Manchester City third. The rest of the top 10 is made up of the likes of Christian Benteke (Liverpool), Matteo Darmian (Manchester United), Xherdan Shaqiri (Stoke), Morgan Schneiderlin (Manchester United), Kevin De Bruyne (Manchester City), Nicolas Otamendi (Manchester City) and Angel Di Maria (Paris St Germain). Unsurprisingly the non-transfer of David De Gea to Real Madrid was the most discussed rumour, ahead of Karim Benzema being linked with Arsenal and Chelsea’s pursuit of John Stones. De Gea was also the most popular individual across the network on deadline day itself, with Arsenal manager Arsene Wenger second as fans raged at his lack of action. Also in the top five were Manchester United new-boy Anthony Martial and West Brom striker Saido Berahino, while Sky Sports’ yellow-tied Jim White also featured. The transfer of Pedro from Barcelona to Chelsea has emerged as the most talked-about signing of the summer on social media. Press Association