The Reflecting-Oven-Jay
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This is a small African predatory bird with a perfectly smooth set of wings with an area of ~100 cm<sup>2</sup>, so maybe the size of a pigeon. It hunts in large flocks, around 10,000 birds to a group (there are plenty of real birds that form flocks this size). 

Using some basic multiplication, this flock can focus about 130 kW of sunlight. The flock decides to kill and eat an elephant, who has a metabolism of around 3000 Watts and already has to work to keep cool on a warm day (heat sink ears, spraying water on itself, etc). By spreading out and focusing sunlight on the elephant, the birds totally overwhelm the elephant's ability to cool itself, raising its body temperature by about a degree Celsius every 2 minutes (130 kW / 4 tons*specific heat of water), leading to slow heatstroke and death. Divided evenly, there's a lb of meat for every bird in the flock, a huge windfall, sustaining the group though any cloudy days until the next kill.