Audubon's planning advice for the Bird-a-Day challenge is to use eBird to see which species visit your area at different times of year, then build a monthly hit list. This planner does the bookkeeping. Paste your own list with the months each bird is around, and it shows how many days you have to fill, how many species you have to fill them with, and which birds to spend each month. It runs in your browser and nothing is uploaded.
The example list loads on your first visit. Its month windows are invented for the demo, so replace it with your own.
How to write your list
Each line is a species name, a vertical bar, then the months the bird is usually around where you bird. Lines starting with # are ignored.
| You type | The planner reads |
|---|---|
Northern Cardinal | all |
Present every month (a line with no bar means the same) |
Dark-eyed Junco | Oct-Apr |
October through April; ranges can wrap past December |
Yellow-rumped Warbler | Oct-Nov, Apr-May |
Two separate windows |
! Snow Bunting | Dec-Feb |
! marks a bird you want spent early, such as a scarce or hard-to-find one |
To fill in the months, open the eBird bar chart for your county or a favorite hotspot. The eBird Help Center says you can reach it from the Bar Charts link on any region or hotspot page, or from the main Explore page. Each bar shows frequency, which eBird defines as "the proportion of complete checklists reporting that species within a specified date range and region." Taller bars mean a species is reported on more checklists. The tallest bar height covers frequencies from 0.6 to 1.0, and an empty gray box means the species was not reported in that period. Write down the months where a bird shows a bar you would trust.
To find candidates you have not thought of, eBird's Targets tool lists species reported in a region and range of months that are missing from one of your eBird lists. It can sort them by frequency, "the percentage of complete checklists that have reported the species." Month and day targets work the same way for your eBird month and day lists.
The formula
The planner shows four numbers and runs one check:
| Term | Meaning | How it is worked out |
|---|---|---|
| D | Days you still need a bird for | End date − start date + 1 |
| P | Species pool | Birds on your list that you have not logged yet and that are present in at least one month between the two dates |
| P − D | Surplus or shortfall | Positive: spare birds. Negative: the list cannot cover the run |
| P ÷ D | Pool per day | Must be at least 1.00 to have any chance |
P ≥ D is necessary but not enough. Timing matters too, because you can only log one bird per day. Twenty birds that are only around in winter cannot cover twenty days in July. So the planner also walks through the dates one at a time. Each day it picks the unused bird whose window closes soonest. Ties go first to ! birds, then to birds present in fewer months of the year, then to list order. The first day with no unused bird present is the projected end of the run. This "last chance first" order is a simple scheduling rule, not a forecast. Your real list will change with weather, travel and luck.
- Days to fill (blue, solid): one bird per day adds up to 365 by December 31 in a non-leap year.
- Species available so far (green, dashed): an imaginary 258-species list, counting each bird from the first month it is present. Illustrative numbers only.
- Lines cross in early July: from here the days outrun the birds, so this list's run would end around then, however the birds are ordered.
- Year-end shortfall: 365 − 258 = 107 days with no new bird on this list.
Why spend the scarce birds first
The ordering follows the strategy in Audubon's Bird-a-Day coverage. The 2017 article advises: "always note the most unusual species you see," and save the regulars for a day when you are too busy or stressed to do some real birding. Its seasonal sketch is that winter is good for waterfowl, spring brings songbirds, summer suits shorebirds and fall brings raptors. Rene Ebersole's 2012 run shows the squeeze. Her winter birds left in March, the new spring migrants were harder to identify, and she ended on April 1, Day 92, with a Rock Pigeon.
The arithmetic for a full year is hard too. Audubon notes that more than 700 species can be found regularly in the United States and Canada, counting ABA codes 1, 2 and 3. A full calendar year needs 365 of them, spread one per day.
Reading the results
- Shortfall overall (P − D below zero): add birds. Look at eBird Targets for nearby counties or hotspots. When you travel, Audubon suggests making the most of local specialties.
- Enough birds but a gap month: find the month where Uncovered is above zero. Then look for birds present in that month, or move a trip into it.
- Big surplus: hold your reserve. Those are your sick-day and busy-day birds.
- Update as you go: paste each day's bird into Already logged, or keep the list in the streak tracker and paste its export here.
For the rules and house-rule choices, see the Bird-a-Day challenge guide. To grow the year-round part of your list at home, start with what to feed backyard birds and the common backyard birds profiles.
Privacy
No analytics, no cookies, no server. If your browser allows local storage, the planner saves your list and end date under one item (birdaday-planner-v1) on this device only. Clear deletes it. Without storage it still works, but the list resets when you leave.
Sources
- Boost Your Birding Skills by Seeing a New Bird Every Day This Year — Audubon (2017)
- Bird-A-Day Challenge — Audubon (2011)
- Bird-A-Day Challenge Ends on Day 92 — Audubon (2012)
- eBird Bar Charts and Graphs — eBird Help Center
- eBird Alerts and Targets FAQs — eBird Help Center
- eBird Targets — eBird news
- Month and day targets — eBird news