I like LIghtroom Mobile, though I use only the free portions, not the parts that require a subscription. It's a very useful editor and also, on my phone, includes a good camera app (whose HDR option is quite good at capturing the bright whites of egrets). You can find a collection of posts by Julianne Kost (some text, some video) with lots of tips for the app, including how to edit photos directly from the Camera Roll.
Julieanne Kost's Blog | Adobe Lightroom Mobile
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