Figure 1
Map of states and provinces used for detailed analyses of number of participants, effort, and number of species recorded.
Table 1
Number of states and provinces showing declines and increases in number of CBC counts in 2020 compared with that predicted based on trends of the previous 10 years. Results by state are in Supplemental Tables 1 and 2.
| UNITED STATES | CANADA | ||
|---|---|---|---|
| Declined | Total | 42 | 10 |
| Outside 95% CI | 31 | 7 | |
| <10% | 21 | 2 | |
| 10–20% | 14 | 6 | |
| >20% | 7 | 2 | |
| Increased | Total | 7 | 3 |
| Outside 95% CI | 4 | 1 | |
| <10% | 6 | 0 | |
| 10–20% | 0 | 0 | |
| >20% | 1 | 3 | |
| As predicted | 1 | 0 |
Figure 2
Spatial distribution of Christmas Bird Counts in California (a) and Saskatchewan (b) prior to the pandemic (2019) and during the pandemic (2020). Each circle represents one count.
Table 2
Differences in spatial distribution of CBC counts in 2019 and 2020 for California and Saskatchewan, two regions exhibiting the greatest reduction in counts owing to the pandemic. Mean distance between counts was produced by proximity analysis in ArcMap. Restriction in coverage is the difference in spatial limit in 2019 compared with 2020 in each of the cardinal directions.
| CALIFORNIA | SASKATCHEWAN | ||
|---|---|---|---|
| Mean distance between counts: | 2019 | 32.697 km ± 1.2 | 47.799 km ± 4.5 |
| (km ± SE) | 2020 | 35.881 km ± 1.7 | 49.035 km ± 7.5 |
| (P = 0.13) | (P = 0.89) | ||
| Restriction in coverage: | North | 0 | 54.887 km |
| South | 0 | 128.963 km | |
| East | 34.950 km | 105.431 km | |
| West | 0 | 96.307 km |
Table 3
Mean difference between actual values of numbers of participants and effort in Christmas Bird Count for 2020 and values predicted based on linear regression for the previous 10 years, for a subset of states and provinces. Negative numbers represent a decrease in 2020 relative to the expected values based on linear regression. With a Bonferroni Correction Factor applied, P-values < 0.001 are considered significant; other levels are shown for reference.
| STATE OR PROVINCE | PARTICIPANTS (NO. OF PEOPLE) | TOTAL EFFORT (HOUR) | EFFORT(HOUR/PERSON) | SPECIES RECORDED |
|---|---|---|---|---|
| Alabama | –0.846 | 3.323 | 0.193 | 2.037 |
| Alaska | –1.296 | –7.645 | 0.216 | –0.453 |
| California | –8.677*** | 6.912 | 0.716*** | 1.544 |
| Hawaii | –3.457 | –0.440 | 0.295 | 1.642 |
| Iowa | –2.622* | 11.617** | 1.183*** | 2.574** |
| Maine | –0.381 | 13.161*** | 0.919** | 2.773* |
| Maryland | –1.264 | 21.775** | 0.858*** | 6.432*** |
| Oklahoma | –1.983 | 11.335 | 1.020** | 7.472** |
| Wyoming | –3.026* | –3.796 | 0.269 | 0.188 |
| Quebec | –0.986 | 10.882* | 0.492 | 4.280*** |
| Saskatchewan | –0.641 | 6.967 | 0.165 | –0.225 |
| w/o SKSA | –3.157* | –0.990 | 0.156 | –0.343 |
[i] SKSA: Saskatoon count.
* P < 0.05; ** P < 0.01; *** P < 0.001.