Permanent and temporary mate-switching in a long-lived seabird: Insights from a 64-year study

In long-lived monogamous animals, pair bonds play a crucial role in
breeding success. In many predominantly monogamous animals, however, there
is often some degree of mate-switching. Mate-switching may represent an
opportunity to acquire a higher quality partner or breeding site following
breeding failure. Using a 64-year dataset, we investigated the dynamics of
mate-switching in Leach’s storm-petrels (Hydrobates leucorhous). We
observed that, on average, 4.3 % of pairs permanently switched mates each
year (i.e., permanent mate switch), with an increasing rate in recent
years. A small proportion (1.1 % annual average) of pairs switched mates
but reunited in a later year (i.e., temporary mate switch). As expected
from previous studies, breeding failure was a significant predictor of
permanent mate-switching. But temporary mate-switching was unrelated to
breeding failure, suggesting these two kinds of mate-switching are caused
by different decision-making processes. Rising global mean temperatures
(GMT) was associated with increases in both temporary and permanent mate
switching rates, raising the possibility that ongoing climate change will
destabilize future population dynamics in this declining seabird species.