How long do birds in the southernmost forests of the world live? Maximun longevity estimates
The ecology of southern forest birds is little known, and even less is known on their longevity.
Here, based on monthly mist netting data of more than 12 years we report on the maximum
longevity of forest passerine birds and we model the relationship of longevity with body mass,
month of the first capture, and migratory status. Between March 2000 to August 2013, in a
mixture of deciduous and evergreen forests at the Omora Ethnobotanical Park (56oS), on
Navarino Island, southern Chile, we caught 1,026 individuals at least twice from the 10 most
abundant bird species. We estimated longevity based on the time period between the first and last
capture of each individual in the mist nets. To evaluate the effects of variables on longevity we
ran a generalized linear model.
Our results show that the longest lived species were the migrant
tyrannid White-crested Elaenia (Elaenia albiceps, 15g, 8.15 years), the resident emberizid
Patagonian Sierra-finch (Phrygilus patagonicus, 23g, 7.60 years), and the resident furnarid
Thorn-tailed Rayadito (Aphrastura spinicauda, 12g, 6.85). However, mean longevity for these
species was 1.27 (n=123), 0.89 (n=318), and 0.80 (n=427) years, respectively. The results of the
generalized linear model indicate that the date of first capture, the body mass, and the month
when a bird was captured were the factors that best explained the longevity of the
birds. Although the three migratory species were twice as small (14.08g) as the 6 resident species
(28.97g), there was no effect of body mass on longevity. The estimated longevities are
conservative values of how long each bird species can live as most of these birds were banded as
adults and they still lived after their last recapture.