How we build our guides
Perch Supply doesn't hand-write thousands of pages, and it doesn't generate filler either. Every guide on this site is rendered from a structured dataset, every field in that dataset is checked against a published source, and pages that can't meet the bar never reach search engines. This page explains exactly how that works.
The honesty rule
A page is published only when its dataset entry is complete and sourced. If we can't verify that a bird nests in a state, the page for that bird and state simply doesn't exist — there is no placeholder, no swapped-in place name, no Mad Libs. Every guide ends with a sources block citing the references behind it.
The datasets
These are the structured datasets behind the site. Each one is maintained as data first, so when a record improves, every page built from it updates at once.
| Dataset | What it holds | Size |
|---|---|---|
| Species profiles | 200+ North American species — diet by season, nesting timing, feeder fit, nest-box specs, similar species. Sourced from Cornell All About Birds and Audubon field guides. | 200+ species |
| Species by state & province | Presence (resident, breeding, winter, migrant) with nesting windows, matched to state and provincial breeding-bird atlases and eBird seasonal bars. Published pages need at least five region-specific details. | 2,900+ pages |
| Birds by city | Sunrise, daylight length and nesting timing computed from each city's own coordinates (NOAA solar tables, Hopkins' law), with nearby cities and local plants. | 1,600+ cities |
| Native plants for birds | 101 plants mapped to the birds they feed, by state, drawing on Audubon Native Plants databases and university extension services. | 101 plants · 1,980 pages |
| Nest-box specifications | Entrance-hole diameter, floor size, mounting height and seasonal calendars for 27 cavity-nesting birds, from Cornell nest-box plans and NestWatch records. | 27 species · 61 states |
| Bird calendar | Monthly presence, nesting and feeding guidance for every species across 12 months, derived from the species range data with latitude shifts. | 2,320 pages |
| UK & Europe garden birds | A separate dataset — different species, British English, metric units — checked against the BTO Bird Atlas and national atlases. | 650+ pages |
| Look-alike comparisons | Only genuinely confused pairs — Downy vs Hairy, crow vs raven, House Sparrow vs House Finch — with field marks from Cornell and Audubon. | 15 pairs |
Sources we rely on
Facts are drawn from these references — the same ones ornithologists and nest-trail monitors use. Where a source is regional (a state breeding-bird atlas, for example), that fact is only applied to the region it covers.
- Cornell Lab of Ornithology — All About Birds
- Audubon Bird Guide
- Audubon Native Plants Database
- eBird — range and seasonal data (public summaries)
- USDA Plant Hardiness Zone Map
- NOAA Solar Calculator — sunrise and daylight
- British Trust for Ornithology — Bird Atlas 2007–11
- Cornell Lab NestWatch — nest-box specifications
- State and provincial breeding bird atlases
The uniqueness gate
Search engines penalize thin, templated content, and so do we. Each guide is scored on how much of it is unique to its place or month: presence status, nesting windows, hand-checked records, city coordinates, local native plants and seasonal foods. A page needs at least five region-specific details to appear in search and in our sitemap. Pages below the bar still load for visitors — they're just marked noindex, so Google and Bing never see them. Roughly 1,000 pages on this site currently fail that gate, and we're fine with that.
What we won't do
- · No invented facts — when a field can't be sourced, it stays empty and the page leaves it out.
- · No fake reviews, testimonials or affiliate filler anywhere on the site.
- · No AI-generated bird photography — verified real photos only, credited to their contributors.
- · No pages built by swapping a place name into the same paragraph — every page earns its place with per-place data.
Corrections
Found something wrong? Send us the correction with the source you'd check it against. Verified fixes go into the dataset and every affected page updates automatically — that's the point of building from data.
Frequently asked
Where does the bird information on Perch Supply come from?
Every fact traces to a published source — primarily the Cornell Lab of Ornithology's All About Birds, Audubon's Bird Guide, state and provincial breeding-bird atlases, eBird seasonal data, USDA hardiness zones and NOAA solar tables. Each page lists its sources at the bottom.
Why do some guides exist for one state but not another?
Pages are generated from data, not templates. A species-by-state page only exists when our dataset has sourced presence data for that state and enough region-specific detail — including at least two native plants that feed the bird there. If the data is thin, the page doesn't exist.
What is the uniqueness check?
Every guide must carry at least five details specific to its place or month — status, nesting window, local plants, city coordinates, seasonal foods. Pages that fall short still render for visitors but are marked noindex and left out of our sitemap, so search engines never see thin content.
Do you use AI-generated bird photos?
No. We only use verified real photography, credited to Wikimedia Commons and USFWS contributors. Species without a verified photo get a typographic header instead of a fake image.
How do I report an error?
Use the contact form. Corrections that check out against the cited sources are applied to the dataset within days, and the affected pages update automatically.