Low flight and wildlife

I see on a sectional chart a box that says "The Islands, Rocks, and Reefs
along the Pacific Coast-Line from 42°00'N to 46°00'N are National Wildlife
Refuges. Low flights may disturb wildlife resulting in a violation of Federal
law."

Unfortunately, the chart doesn't say what constitutes "low flight." What
altitudes do they have in mind?

Also, when there are areas that say "Pilots are requested to maintain a
minimum altitude of xxxx' AGL ..." just how strong a "request" is it? What
happens if you fail to heed the request?

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