Photo Contests Here and Abroad Grab Rights
By entering the contest, photographers agree to have their submitted photograph displayed on the www.VisitAlleganCounty.com or www.AlleganCounty.org websites without any fee or other form of compensation, and agree that the Allegan County Tourist Council may use all submitted photos - whether selected as official "winners" or not - for any future promotional or advertising purposes without further written consent. Images may also be submitted to other tourism-related organizations (including, but not limited to, Travel Michigan and West Michigan Tourist Association) and other media sources for promotional use.
Note that if you submit your photo via a negative, the negative will not be returned! At least a "Photo credit will be given" for the uses.
Across the pond, a respected British wildlife charity, the Wildfowl and Wetlands Trust, and Nikon are sponsoring a photo contest. The rules there state that:
[I]n consideration of their providing the Competition, each entrant grants a worldwide, irrevocable, perpetual licence to WWT to feature any or all of the submitted images in any of their publications, their websites and/or in any promotional material connected to this competition for a period of no more than five years.
Note that in the United States, courts construe ambiguities of contract language against the drafter. Therefore, the "perpetual" license likely would be limited by the five years clause.
Sometimes, it might be more "considerate" to not provide a competition than to grab photo rights.
Thanks to Joel DeYoung and Roger Whitehead for submitting these alerts.