Chinese-developed nuclear battery has a 50-year lifespan - Mao Clone 01-13 07:35 | 207.4 KB | link   Rate

https://emiratitimes.com/chinas-nuclear-battery-50-years-life-on-a-single-charge/

"..While the battery's initial power output is relatively low at 100 microwatts, Betavolt is optimistic about boosting this to 1 watt by 2025..."

A capacitor stores the energy  for take-off ..and regular power output for sustained long distance flight

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https://bcrc.bio.umass.edu/courses/spring2019/biol/biol312section2/content/mechanical-power-output-and-forward-velocity-birds

For cockatiels, the minimum power output was 1.3W at a speed of 5 ms^-1. The maximum power output was 3.7W at a speed of 14 ms^-1

https://cockatielworld.co.uk/cockatiel-size/#:~:text=Cockatiels%20typically%20weigh%20between%2075,that%20enables%20them%20to%20fly.

 Cockatiels typically weigh between 75 to 125 grams, which is approximately the weight of a bar of soap. This lightweight nature is due to their hollow bone structure, an evolutionary feature that enables them to fly.