10.5061/DRYAD.0GB5MKM45
Feldman, Mariano J.
0000-0002-2966-5562
Université du Québec en Abitibi-Témiscamingue
Mazerolle, Marc J.
Université Laval
Imbeau, Louis
Université du Québec en Abitibi-Témiscamingue
Fenton, Nicole J.
Université du Québec en Abitibi-Témiscamingue
Data from: Beaver activity and red squirrel presence predict bird
assemblages in boreal Canada
Dryad
dataset
2022
FOS: Natural sciences
automated recorders
Bayesian hierarchical model
beaver
boreal peatland
multispecies occupancy
red squirrel
species richness
Natural Sciences and Engineering Research Council
https://ror.org/01h531d29
Fiducie de Recherche sur la Forêt des Cantons-de-l’Est
2023-01-23T00:00:00Z
2023-01-23T00:00:00Z
en
https://doi.org/10.1093/ornithology/ukad009
https://doi.org/10.5281/zenodo.7349219
35446 bytes
7
CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
Wetlands and predation in boreal ecosystems play essential roles
throughout the breeding season for bird assemblages. We found a positive
association of beaver activity and a negative influence of American red
squirrels (Tamiasciurus hudsonicus) on bird assemblages. We used a
multispecies hierarchical model to investigate whether bird communities
differ between two major wetland habitats in boreal Canada: beaver ponds
and peatland ponds. In addition to including variables such as forest
cover and latitude, we adopted a structural equation model approach to
estimate the occupancy of American red squirrels and its potential
influence on bird communities. Using automated recording stations deployed
at 50 ponds, we detected 96 bird species in 2018 and 2019. Bird species
were grouped into four taxonomic guilds according to their habitat
successional requirements: early successional species, late successional
species, generalists, and wetland species. Beaver ponds harbored higher
species richness, a pattern driven primarily by early successional
species. The occupancy of almost a quarter of the species was lower in the
presence of red squirrels. Late successional species responded positively
to the cover of forest surrounding the pond. Our results highlight the
value of considering acoustic data of red squirrels to quantify habitat
quality in boreal forests. We conclude that beaver activity shapes bird
assemblages through modification of their habitat, and that some bird
guilds are associated negatively with the presence of American red
squirrels.
Acoustic sampling and covariates. We used a SM4 Song meter (Wildlife
Acoustics Incorporation, Concord, Massachusetts, USA) at each pond to
record bird and squirrel vocalizations. During a given sampling period,
ARUs were set with both microphones facing upward for four consecutive
days to record a 5-min sample at 00600 h. Each file was encoded at a
sampling rate of 44.1 kHz and a 16-bit resolution. Each pond was sampled
for four consecutive days during two periods in both years, yielding an
average of 80 minutes per pond. All recording data were analyzed by an
ornithologist with extensive field experience in the study region to
identify species based on their vocalizations or other aural cue. Species
were categorized into four guilds based on their requirements for various
successional stages of black spruce: (1) early successional species,
associated with open areas of low-vegetation such as young forests or
regenerating shrublands; (2) late-successional species preferring older
forest stands; (3) generalists, consisting of species that use a wide
range of successional stages; and (4) wetland and aquatic species. In
addition to birds, we identified the vocalizations of the American red
squirrel from recordings for use in occupancy analysis. We included four
candidate variables as potential predictors of boreal bird occupancy: pond
type, red squirrel latent occupancy, proportion of all forest types over 2
m (deciduous, mixed, and coniferous forest) within circular buffers of
1000 m centered on acoustic recorder locations, and we included latitude
to reflect habitat changes in the study area. We considered two parameters
that potentially influenced detection probability during acoustic surveys:
the quality of the recording and the number of days after snowmelt. Data
processing and analysis. We investigated occupancy patterns of the
American red squirrel, and the entire bird community detected at least
once in our recordings. We prepared detection histories for each species
at each pond, where we indicated detection (1) or non-detection (0) in
each recording of the two periods of four consecutive days in each year.
Each pond in each year was considered as an independent site and we
included a fixed year effect as well as a site random effect to account
for potential differences in occupancy between years. Thus, detection
histories for a given species were arranged in a matrix of 100 rows (50
sites x 2 years) and 8 columns (4 recordings x 2 periods). We estimated
bird community structure with a multispecies site-occupancy model. We
adapted a structural equation strategy to our multispecies occupancy
model. Specifically, one component of our model estimated the occupancy of
American red squirrels as a function of different explanatory variables,
and then used the latent squirrel occupancy as an explanatory variable in
the multispecies occupancy model for the bird communities. We used the
multispecies model to derive the species richness from the posterior
distribution of the true occurrence of each species at each site,
expressed as the mean of the posterior distribution. We investigated the
relationship between species richness against the explanatory variables
pond type, forest cover, latitude, and the posterior mean of the squirrel
occupancy state in a linear mixed-effect model.
The description of each column header for each spreadsheet is provided in
an associated ReadMe file. The steps to follow for each analysis are
provided in Supplementary material the R code files. The final dataset
included detection/non-detection data for 96 species from 50 ponds from
May to August 2018 and 2019 ("Bird_multisp_v2.Rdata"). This
dataset is shared in one file in the form of a 3-dimensional array table,
which contained rows for pond units (n=100), columns for visits (n=8), and
rectangular matrices for species (n=96). Please contact the author for any
additional inquiries of how data was collected and analyze.