Table 1.
Probability that a female who parasitizes an active nest will by chance have a birth nestmate as host, depending on the age of the female and the distance of the parasitized nest from her birth nest
| Nest distance | Age of female in years (no. of females)
|
|||||
|---|---|---|---|---|---|---|
| 2 (24) | 3 (18) | 4 (10) | 5 (6) | 6 (3) | Mean | |
| 0 | 0.083 | 0.111 | 0.400 | 0.167 | 0 | 0.19 |
| 1–2 | 0.105 | 0.083 | 0.125 | 0 | 0 | 0.078 |
| 3–6 | 0.042 | 0.028 | 0 | 0 | 0 | 0.0175 |
| 7–20 | 0.0030 | 0.016 | 0.0079 | 0 | 0 | 0.0067 |
Nest distance is counted in number of active nests from the female's birth nest (0). The results are based on all females returning (and present at the age specified) of 1,172 chicks wing-tagged as nestlings. For instance, at age 3, 2 of 18 females present (P = 0.111) would have parasitized a birth nestmate (social mother or sister) by laying eggs in the birth nest (0). Means are for ages 2–5.