Data from: Condition-dependent immune response in a migrating shorebird, the common snipe Gallinago gallinago

Bird migration, as an energy-demanding activity, is expected to generate
allocation trade-offs between important biological processes, such as
immune response. On one hand, long-distance migratory flights may require
redirection of resources from immune response and promote temporal
immunosuppression. On the other hand, individuals in high body conditions
may have the capacity to cope with the costs of migration while
maintaining adequate levels of immune activity. Here, we investigated the
covariation of immune response and two measures of condition in a
short-distance migratory shorebird, the common snipe Gallinago gallinago.
We captured and experimentally induced immune response using
phytohaemagglutinin (PHA) in 148 snipes during the autumn migration. We
found a positive relationship between PHA-induced immune response with
indices of body condition reflecting aerobic capacity (total blood
haemoglobin concentration) and the level of accumulated energy reserves
(size-corrected body mass). The results provided evidence for
condition-dependent immune response in migrating snipes, indicating that
high-quality individuals are capable of sustaining optimal, non-suppressed
immune responses during migration. We suggest that abundant food resources
at high-quality stopover sites may help individuals rapidly replenish body
reserves essential for the effective functioning of the immune system. It
also seems likely that the maintenance of adequate immune function or its
upregulation may confer significant adaptive advantages under ecological
conditions of increased pathogenic exposure during migration.