Population Ecology


, Volume 148, Issue 3, pp 405-413

First online:

Importance of adult survival, local recruitment and immigration in a declining boreal forest passerine, the willow tit Parus montanus

  • Satu LampilaAffiliated withDepartment of Biology, University of Oulu Email author 
  • , Markku OrellAffiliated withDepartment of Biology, University of Oulu
  • , Eduardo BeldaAffiliated withDepartament de Ciència Animal, Universitat Politècnica de València
  • , Kari KoivulaAffiliated withDepartment of Biology, University of Oulu

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Population growth rate (λ) and its components (adult survival, local recruitment, immigration and their relative contributions to λ) were studied in the declining willow tit Parus montanus in Northern Finland. Capture–recapture models for open populations were used to estimate the population parameters and their process variation. Adult survival was fairly high with low variation (0.593, CV=0.067). As expected, local recruitment was lower and more variable (0.063, CV=0.610). During the 12-year study, the population growth rate averaged to one (0.988, CV=0.197; calculated as \( {\hat{\sigma }_{{{\text{process}}}} } \mathord{\left/ {\vphantom {{\hat{\sigma }_{{{\text{process}}}} } {{\text{mean}}}}} \right. \kern-\nulldelimiterspace} {{\text{mean}}}). \) However, if the present processes continue, population projections show that the population is likely to decline. There was considerable temporal variation in the relative contributions of demographic parameters to λ. In all years, adult survival had the highest relative contribution (mean 64%) to the population growth rate and it was the least variable trait. Immigration had a higher relative contribution (22%) to λ than local recruitment (14%). Based on the results for the contributions to λ, the main conservation concern for willow tits is adult survival. Due to low variation, adult survival may be difficult to enhance, but at least it should be prevented from declining. High stochasticity in local recruitment and immigration is probably an inherent characteristic of highly seasonal environments, making these traits difficult to address for conservation practices.


Capture–recapture Population growth Process variation MARK