Final statistics of Swallow Nest Boxes at Buttertubs West Marsh.
Number of boxes: 36
Number of boxes with eggs: 24 (67%)
Number of eggs laid: 138
Mean clutch size (range): 5.3 (3-6)
Number of eggs hatched (% eggs hatched): 120 (87%)
Number of nestlings banded (% nestlings banded): 97 (81%)
Number of females banded: 21
Number of males banded: 4
Number fledged (% nestlings fledged): 83 (69%)
% eggs to fledglings: 50%
Fledging rate (young per pair): 3.2
Summary statistics of Tree Swallow nesting productivity at Buttertubs West Marsh during 2018-2022, and 10-year average.
| Parameter | 2018 | 2019 | 2020 | 2021 | 2022 | 10-year Average |
| Number of boxes | 30 | 30 | 36 | 36 | 36 | — |
| Number of boxes with eggs (% of boxes with eggs) | 24 (80%) | 21 (70%) | 29 (81%) | 27 (75%) | 20 (56%) | 21 (65%) |
| Number of eggs laid | 135 | 141 | 193 | 194 | 131 | 126 |
| Mean clutch size (range) | 5.0 (1-7) | 5.0 (2-7) | 5.1 (2-7) | 5.1 (3-7) | 5.7 (2-7) | 5.1 |
| Number of eggs hatched (% eggs hatched) | 115 (85%) | 106 (75%) | 148 (77%) | 119 (61%) | 116 (89%) | 94 (73%) |
| Number of nestlings banded (% nestlings banded) | 105 (91%) | 97 (92%) | 92 (62%) | 88 (74%) | 115 (99%) | 78 (85%) |
| Number fledged (% nestlings fledged) | 62 (54%) | 84 (79%) | 76 (51%) | 50 (42%) | 97 (84%) | 60 (66%) |
| % eggs to fledglings | 46% | 60% | 42% | 26% | 74% | 49% |
| Fledging rate (young per pair) | 2.3 | 3.0 | 2.0 | 1.3 | 4.2 | 2.6 |
