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Local and Global Climate Effects on Storm Petrel Demography

Table 1. All covariates used in the analyses, and their main characteristics.

Kind of covariateName Characteristics label Reference period demographic
parameters that could
Available years be influenced

Individual Winter North Atlantic global-scale covariates WNAO December-February 1991–2012 Survival
Individual oscillation
Individual
Individual Temperature anomaly. local scale breeding ground PBT March-April 1991–2012 Survival and breeding
Pre-Breeding period covariate
Individual
Rainfall anomaly. Pre- local scale breeding ground PBR March-April 1991–2012 Survival and breeding
Individual Breeding period covariate

Individual North Atlantic global-scale covariates PBNAO March-April 1991–2012 Survival and breeding
Individual oscillation. Pre-Breeding
Individual period

Individual Integrative climatic PCA derived integrative PC1PB March-April 1991–2012 Survival and breeding
Individual index 1 Pre-Breeding covariates
Individual period
External
External Integrative climatic PCA derived integrative PC2PB March-April 1991–2012 Survival and breeding
index 2 Pre-Breeding covariates
period

Temperature anomaly. local scale breeding ground BT May-August 1991–2012 Survival and breeding
Breeding period covariate May-August 1991–2012 Survival and breeding
May-August 1991–2012 Survival and breeding
Rainfall anomaly. local scale breeding ground BR
Breeding period covariate

North Atlantic global-scale covariates BNAO
oscillation. Breeding
period

Integrative climatic PCA derived integrative PC1B May-August 1991–2012 Survival and breeding
Survival and breeding
index 1 Breeding region covariates Survival and breeding
Survival
Integrative climatic PCA derived integrative PC2B May-August 1991–2012 Survival

index 2 Breeding region covariates

West Sicily Rainfall index PCA derived integrative WSR May-April 1991–2012
covariates

Sea surface temperature PCA derived integrative SST December - February 2001–2010
covariates

Chlorophille concentration PCA derived integrative CHL December - February 2001–2010
covariates

In the table we reported time-dependent individual covariates as ‘‘individual’’ and environmental covariates as ‘‘external’’.
doi:10.1371/journal.pone.0094526.t001

subsequent age classes. The assumptions underlying our model 2 W1|(1{Y1) W1Y1 3
are: a. detection probability of non-breeders and skippers is zero; W2 1{W1
b. once in the breeder state, individuals cannot go back to the non WY~46 0 0 1{W2 75,
breeder state; c. there is an age from which the probability of
becoming a breeder (probability of transition from non breeder to 0 1
breeder) levels off at a constant value. As a consequence, at a given
sampling occasion, an animal may be a pre-breeder (a juvenile of 23
one year or more, not yet recruiting, state PB), breeder (adults after p 00
first breeding are generally considered breeders, state B), or dead
(state dead, unobservable). The following observations may be B~64 1{p 0 p 75:
made: ‘1’ (if detected as chick), ‘2’ (if detected as adult) and ‘0’ (if 1 00
not detected). We tested the full recruitment age (the age at which
any bird has become a breeder) and the age of full breeding Columns of the matrix P and WY correspond respectively to
(considering the probability of becoming a breeder as a function of
age). To address age variation in the probability of becoming a state PB, B and dead, columns of the matrix B correspond to the
breeder, we used only individuals of known age, i.e., only those
ringed as chicks (3135), considering ringing as chicks as first observations ‘non detected’ and ‘detected’ while rows of the
capture event. We define the initial state vector P, the transition matrices WY and B correspond respectively to state PB, B, and
matrix WY (survival multiplied by transition between states dead. W1denotes the pre-breeder survival, W2 the adult survival,
conditional on survival) and the event matrix B. Y1is the probability of becoming a breeder and p is the detection
probability.
P~½ p 1{p 0Š ,
Individuals are first captured as PB and then become B; p
denotes the proportion of newly marked in state PB. W16Y1
represents the probability that a pre-breeder survives and attempts

PLOS ONE | www.plosone.org 3 April 2014 | Volume 9 | Issue 4 | e94526