title: Using dynamic N-mixture models to test cavity limitation on northern flying squirrel demographic parameters using experimental nest box supplementation.
abstract: Dynamic N-mixture models have been recently developed to estimate demographic parameters of unmarked individuals while accounting for imperfect detection. We propose an application of the Dail and Madsen (2011: Biometrics, 67, 577-587) dynamic N-mixture model in a manipulative experiment using a before-after control-impact design (BACI). Specifically, we tested the hypothesis of cavity limitation of a cavity specialist species, the northern flying squirrel, using nest box supplementation on half of 56 trapping sites. Our main purpose was to evaluate the impact of an increase in cavity availability on flying squirrel population dynamics in deciduous stands in northwestern Québec with the dynamic N-mixture model. We compared abundance estimates from this recent approach with those from classic capture-mark-recapture models and generalized linear models. We compared apparent survival estimates with those from Cormack-Jolly-Seber (CJS) models. Average recruitment rate was 6 individuals per site after 4 years. Nevertheless, we found no effect of cavity supplementation on apparent survival and recruitment rates of flying squirrels. Contrary to our expectations, initial abundance was not affected by conifer basal area (food availability) and was negatively affected by snag basal area (cavity availability). Northern flying squirrel population dynamics are not influenced by cavity availability at our deciduous sites. Consequently, we suggest that this species should not be considered an indicator of old forest attributes in our study area, especially in view of apparent wide population fluctuations across years. Abundance estimates from N-mixture models were similar to those from capture-mark-recapture models, although the latter had greater precision. Generalized linear mixed models produced lower abundance estimates, but revealed the same relationship between abundance and snag basal area. Apparent survival estimates from N-mixture models were higher and less precise than those from CJS models. However, N-mixture models can be particularly useful to evaluate management effects on animal populations, especially for species that are difficult to detect in situations where individuals cannot be uniquely identified. They also allow investigating the effects of covariates at the site level, when low recapture rates would require restricting classic CMR analyses to a subset of sites with the most captures.
authors.affiliation: Chaire industrielle CRSNG-UQAT-UQAM en Aménagement Forestier Durable, Institut de Recherche sur les Forêts, Université du Québec en Abitibi-Témiscamingue 445 boul. de l'Université, Rouyn-Noranda, QC, J9X 5E4, Canada ; Centre d'Étude de la Forêt, Université du Québec en Abitibi-Témiscamingue 445 boul. de l'Université, Rouyn-Noranda, QC, J9X 5E4, Canada.
authors.forename: Pauline
authors.initials: P
authors.lastname: Priol
authors.affiliation: Centre d'Étude de la Forêt, Université du Québec en Abitibi-Témiscamingue 445 boul. de l'Université, Rouyn-Noranda, QC, J9X 5E4, Canada.
authors.forename: Marc J
authors.initials: MJ
authors.lastname: Mazerolle
authors.affiliation: Chaire industrielle CRSNG-UQAT-UQAM en Aménagement Forestier Durable, Institut de Recherche sur les Forêts, Université du Québec en Abitibi-Témiscamingue 445 boul. de l'Université, Rouyn-Noranda, QC, J9X 5E4, Canada ; Centre d'Étude de la Forêt, Université du Québec en Abitibi-Témiscamingue 445 boul. de l'Université, Rouyn-Noranda, QC, J9X 5E4, Canada.
authors.forename: Louis
authors.initials: L
authors.lastname: Imbeau
authors.affiliation: Département des Sciences Biologiques, Chaire industrielle CRSNG-UQAT-UQAM en Aménagement Forestier Durable, Université du Québec à Montréal P.O Box 8888, Succursale Centre-ville, QC, H3C 3P8, Canada.
authors.forename: Pierre
authors.initials: P
authors.lastname: Drapeau
authors.affiliation: Ministère des Ressources Naturelles, Direction générale de l'Abitibi-Témiscamingue 70 avenue Québec, Rouyn-Noranda, QC, J9X 6R1, Canada.
authors.forename: Caroline
authors.initials: C
authors.lastname: Trudeau
authors.affiliation: Chaire industrielle CRSNG-UQAT-UQAM en Aménagement Forestier Durable, Institut de Recherche sur les Forêts, Université du Québec en Abitibi-Témiscamingue 445 boul. de l'Université, Rouyn-Noranda, QC, J9X 5E4, Canada ; Centre d'Étude de la Forêt, Université du Québec en Abitibi-Témiscamingue 445 boul. de l'Université, Rouyn-Noranda, QC, J9X 5E4, Canada.
authors.forename: Jessica
authors.initials: J
authors.lastname: Ramière
keywords: Abundance; BACI design; Dail–Madsen open N-mixture model; Glaucomys sabrinus; apparent survival; habitat selection; manipulative experiment; recruitment; snags; tree cavities