Table 1.
Overview of activity rhythms in four free-living arctic-breeding birds in relation to sex and breeding stage. Activity patterns were classified into three categories based on Lomb–Scargle periodogram analysis: arrhythmic, no periodicity could be detected; entrained, a significant periodicity was detected that did not differ from 24 h; free-running, a significant periodicity was detected that deviated significantly from 24 h. Note that the three shorebird species have precocial young (parental care only includes brooding, attending and defending the young), whereas the Lapland longspur has altricial young (fed by both parents).
| species | social mating systema | parental care patterna | sex | activity pattern |
||
|---|---|---|---|---|---|---|
| arrhythmic | entrained | free-running | ||||
| semipalmated sandpiper | monogamous | biparental | male | pre-incubation | — | incubation |
| female | pre-incubation | — | incubation | |||
| pectoral sandpiper | polygynous | female only | male | entire season | — | — |
| female | pre-incubation | incubation | — | |||
| red phalarope | polyandrous, sex-role reversed | male only | male | pre-incubation | incubation | — |
| female | entire season | — | — | |||
| Lapland longspur | monogamous, occasional polygyny | biparental (female-only incubation) | male | — | entire season | — |
| female | — | entire season | — | |||