Critter Factbook

Sources and checks

Where every answer comes from

Critter Factbook does not do its own field research. It collects plain statements from agencies and universities that do, and shows them next to each answer so you can judge them yourself.

What counts as a source

  • Species pages from NOAA Fisheries and nature pages from individual U.S. national parks.
  • Fact sheets and guides from university extension services (Colorado State, Clemson, University of Wisconsin–Madison).
  • A page only counts if it states the fact directly. We do not work out answers from charts, and we do not use forums, answer sites or other fact websites.

How a quote is checked

  1. The sentence is copied from the source and stored next to the answer.
  2. Before a page is built, a script searches the source text for that sentence. If a single word differs, the page does not build.
  3. Any number in our one-line answer must also appear in the quoted sentence. If it does not, the page does not build either.
  4. The date in the Checked column is the day the quote was last compared with the source. Pages change, so we compare them again over time and update the date.

Our answers are short paraphrases. When the quote and our answer seem to disagree, the quote wins, and we would like to hear about it: hello@critterfactbook.com.

Scope, and why it matters

Many fact pages are written about one species in one place: bats in Yellowstone, Douglas's squirrels in the Klamath parks, ticks at Fire Island. We keep that label on every answer rather than stretching it to cover the whole animal group. Where two sources give different figures, both are shown.

Use of the material

Text from NOAA Fisheries and the National Park Service is a work of the U.S. government. No claim to original U.S. Government works. We do not use agency logos, and quoting them does not mean they endorse this site.

University extension pages are copyrighted by their publishers. We quote only a sentence or two from each, always with a link back, and write the answers in our own words.

There are no pictures on this site, so none of them are AI-generated or borrowed.

Every source in use

Colorado State University Extension

Clemson Cooperative Extension

Oregon State University Extension

Ohio State University Extension

University of Wisconsin–Madison Extension

NOAA Fisheries

National Park Service