Sergio, F., Tavecchia, G., Taferna, A., López Jimenez, L. Blas, J., De Stephanis, R. Marchant, T. A., Kumar, N. and Hiraldo, F. 2015 No effect of satellite tagging on survival, recruitment, longevity, productivity and social dominance of a raptor, and the provisioning and condition of its offspring. J. App. Ecol. Accepted.
Abstract:
1.The deployment of electronic devices on animals
is rapidly expanding and producing leapfrog advances in ecological
knowledge. Even though their effects on the ecology and behaviour of the
marked subjects are potentially important, less than 10% of the studies
are accompanied by an evaluation of impact, and comprehensive,
long-term assessments have been few. Therefore, there is an urgent need
to test for impacts, especially for tags that are heavy and deployed for
long time periods, such as satellite transmitters.
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| Photo: F. Sergio |
2.We marked 110 individuals of a medium-sized, migratory raptor, the black kite Milvus migrans,
with GPS satellite tags, representing about 4% of the body mass and
attached as backpacks through a Teflon harness. Tagged individuals were
compared to control animals of similar sex, age and breeding status for a
large number of behavioural, condition-related and ecological traits.
3.Despite
a sample size 2–3-fold greater than most previous assessments that
reported significant impacts, there was no detectable difference between
tagged and control individuals in key vital rates such as survival
probability, longevity, recruitment, age of first breeding, reproductive
performance and timing of breeding.
4.Tagged
and untagged kites showed similar social dominance during fights over
food and a similar capability to provision nestlings, which prevented
carry-over effects on the stress levels and condition of their
offspring.
5.Synthesis and applications.
Radio-marking studies are growing exponentially in the current
“movement ecology era” and impact assessments will be ever more
important. In principle, tags of up to 4% mass-load can be deployed
without apparent harm on some avian soaring species, but impacts should
be properly evaluated on a case-by-case basis. Resilient species for
which impacts seem weak could be used as early warning systems for
trials of new devices: if impacts are observed, they are likely to be
even greater on more vulnerable species. Finally, individual fatalities
caused by marking should be taken into serious account, but
comprehensively evaluated in the light of broader population-level
impacts. Future initiatives to minimize tagging impacts could include
more stringent licensing criteria enforcing attendance at training
courses or incorporation of impact evaluations into study designs,
increased availability of training courses for tagging, and enhanced
sharing of information through blogs, workshops or specialized journal
sections.
