Data from: Detailed monitoring of a small but recovering population reveals sublethal effects of disease and unexpected interactions with supplemental feeding

1. Infectious diseases are widely recognized to have substantial impact on
wildlife populations. These impacts are sometimes exacerbated in small
endangered populations, and therefore, the success of conservation
reintroductions to aid the recovery of such species can be seriously
threatened by outbreaks of infectious disease. Intensive management
strategies associated with conservation reintroductions can further
compound these negative effects in such populations. 2. Exploring the
sublethal effects of disease outbreaks among natural populations is
challenging and requires longitudinal, individual life-history data on
patterns of reproductive success and other indicators of individual
fitness. 3. Long-term monitoring data concerning detailed reproductive
information of the reintroduced Mauritius parakeet (Psittacula echo)
population collected before, during and after a disease outbreak was
investigated. 4. Deleterious effects of an outbreak of beak and feather
disease virus (BFDV) were revealed on hatch success, but these effects
were remarkably short-lived and disproportionately associated with
breeding pairs which took supplemental food. Individual BFDV infection
status was not predicted by any genetic, environmental or conservation
management factors and was not associated with any of our measures of
immune function, perhaps suggesting immunological impairment. Experimental
immunostimulation using the PHA (phytohaemagglutinin assay) challenge
technique did, however, provoke a significant cellular immune response. 5.
We illustrate the resilience of this bottlenecked and once critically
endangered, island-endemic species to an epidemic outbreak of BFDV and
highlight the value of systematic monitoring in revealing inconspicuous
but nonetheless substantial ecological interactions. Our study
demonstrates that the emergence of such an infectious disease in a
population ordinarily associated with increased susceptibility does not
necessarily lead to deleterious impacts on population growth and that
negative effects on reproductive fitness can be short-lived.