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  • Date: 05/24/1974
    Resource Category: Peer-reviewed article
    Biological sampling procedures that remove organisms or litter from the system being studied potentially bias the results. Bias can be estimated by considering the experimenter as a consumer in the system, and comparing experimenter consumption to other organisms feeding at the same trophic level. H. T. Odum's classic work is examined in light of ... »
  • Date: 01/01/1880
    Resource Category: Project Descriptions
    The North American Bird Phenology Program houses a unique and largely forgotten collection of six million Migration Observer Cards that illuminate migration patterns and population status of birds in North America. These handwritten cards contain almost all of what was known of bird status from the Second World War back to the later part of the ... »