DOI: 10.5061/dryad.0cfxpnw3r
title: Data from: Asynchrony, density dependence, and persistence in an amphibian

description: The wood frog (Rana sylvatica = Lithobates sylvaticus) is a
 common, early-spring breeding anuran species in the United States and
 Canada. Females typically lay their egg masses in concentrated areas of a
 few meters over several days. Most female wood frogs mature after two
 years. Each female lays one egg mass in a given year, and most show high
 (~100%) site fidelity after first breeding, although a small portion of
 juveniles disperse up to 2000 m away from their natal site before their
 first breeding season. The lifespan of wood frogs depends on latitude, but
 they rarely live longer than five years. From 2000 to 2020 we conducted
 wood frog egg mass counts in 64 freshwater nonpermanent wetlands in the
 3212 hectare Yale-Myers Forest in northeastern Connecticut, USA. The
 wetlands varied in surface area (average = 2642 m2, range = 24–41361 m2,
 CV = 252), canopy closure (i.e., global site factor; average = 52%, range
 = 0–98%, CV = 68), depth (average = 52 cm, range = 22–118, CV = 46), and
 egg mass counts (average = 71, range = 0–1113, CV = 130). As each female
 only lays one egg mass per year (i.e., only produces one clutch) and site
 fidelity is high, egg mass counts offer an accurate proxy for the number
 of breeding females within a pond in a given year. Previous work indicates
 egg mass counts are an accurate and precise technique for monitoring wood
 frog populations.
description: <em>Pond-level
 variables</em> Attributes of ponds in our models
 included maximum pond depth and canopy closure. Depth was recorded at the
 time of egg mass surveys. Most ponds have a permanent depth gauge so
 measurements are standardized across years, otherwise depth was recorded
 as the deepest point in the pond. Pond canopy closure was measured as in
 Arietta et al. (2020) by using five hemispherical photographs taken along
 the shore at each cardinal point and at the center of each pond during
 leaf-off and leaf-on seasons. We estimated average leaf-on and leaf-off
 global site factor (GSF; the ratio of above-canopy radiation to
 under-canopy radiation) (Anderson 1964) and used a weighted GSF value
 integrated over the duration of wood frog embryonic and larval life cycle
 (Halverson et al. 2003). GSF is scaled between 0–1, and we report it here
 as a percentage. <em>Regional-level
 variables</em> We included air temperature and
 Palmer Drought Severity Index as regional-scale variables. Here we define
 regional factors as those affecting multiple breeding populations
 simultaneously. We downloaded daily temperature records from the National
 Climatic Data Center of the National Oceanic and Atmospheric
 Administration (NOAA) observing station at the Windham Airport in
 Willimantic, Connecticut, approximately 19 km south of the study area. We
 estimated winter thaw as the number of days between 1 October and 30 March
 above freezing in the winter prior to breeding (i.e., winter
 thaw<sub>(t-1)</sub>). This date range gives an estimate of
 the fall and winter conditions for juveniles and adults and aligns winter
 temperature with the hydrologic water year that begins 1 October each
 year. The Palmer Drought Severity Index (hereafter
 drought severity) uses temperature, precipitation, and soil information to
 estimate the departure of moisture supply from the norm. We downloaded
 historical monthly drought severity data for Connecticut from the National
 Centers for Environmental Information division of NOAA (available at
 https://www.ncdc.noaa.gov/temp-and-precip/drought/historical-palmers/psi/200011-202010). Drought severity typically ranges between -4 and 4, although more extreme values are possible. A drought severity value around zero indicates normal conditions, whereas a value ≤ -4 indicates extreme drought and a value ≥ 4 extremely wet conditions. We used an average monthly drought severity value from 1 March to 30 September to represent the moisture conditions that breeding adults, tadpoles, and new metamorphs would experience from the highest pond levels (early spring) to lowest levels in late summer and early fall. To test if larval and juvenile conditions affected females during their first breeding year, we also tested a two-year lag in drought severity (i.e., drought severity<sub>(t-2)</sub>) corresponding to the first year of maturity. <em>Estimating density dependence measures</em> Females typically take two years to reach sexual maturity, so the effect of larval intraspecific competition within a focal pond on a breeding female was defined as the density of egg masses (i.e., egg masses / pond area) two years prior. The effect of neighboring ponds (a proxy for terrestrial density dependence) was estimated using a summed function of egg mass data from neighboring ponds (i.e., within 500 m) weighted by inverse distance. Closer ponds are given greater weight in generating the estimate. <em>Population growth rate</em> We defined population growth rate (hereafter growth rate) as the number of breeding females over a generation time of two years: ln((egg masses<sub><sub><sub>t</sub></sub></sub> + 1)/egg masses<sub>(<sub>t</sub><sub>-</sub><sub>2)</sub></sub> +1))/2 <br>Where <em>t</em> is the number of egg masses in the survey year, <em>t-2</em> is the number egg masses two years prior, and the entire function is divided by the number of years between measurements. This approach normalizes high and low values for better comparison across ponds.
description: ReadMe_file.txt information
 <strong>woodfrogdata.csv</strong>
 This is the main data file with all years of data from all ponds.
 This dataset contains 14 columns x 1130 rows
 <strong>Pond.ID</strong> = pond name
 <strong>Year</strong> = year of data
 collection <strong>Depth</strong> = depth
 (cm) of water within a pond during egg mass surveys at depth gauge or in
 deepest point of pond (if no gauge is installed)
 <strong>RASY.Count.1</strong> = independent whole
 pond count of <em>Rana sylvatica</em> egg masses by observer
 1 <strong>RASY.Count.2</strong> =
 independent whole pond count of <em>Rana sylvatica</em> egg
 masses by observer 2
 <strong>Avg.RASY.Count</strong> = average of the two
 independent counts <strong>RASYdens
 </strong>= density of RASY egg masses (Avg.RASY.Count/pond area) in
 egg masses/m<sup>2</sup>
 <strong>GrowthRate </strong>= population growth rate
 as estimated by egg masses (see explanation above)
 <strong>RASYdens_t2</strong> = RASY density two
 years prior to the current year (egg
 masses/m<sup>2</sup>)
 <strong>days_thawed</strong> = number of days between
 1 October and 30 March above freezing in the winter prior to
 breeding <strong>spfaPDSI</strong> =
 average monthly drought severity value from 1 March to 30 September of the
 breeding year <strong>spfaPDSIlag</strong>
 = average monthly drought severity value from 1 March to 30 September two
 years prior to the breeding year
 <strong>wEggs</strong> = number of egg masses in
 neighboring ponds within 500 m of focal pond weighted by distance from
 pond (see data description)
 <strong>distance.mat.csv</strong>
 Distance matrix for distance (in meters) between each pond.
 Dataset is 65 columns x 65 rows.
 <strong>pondinfo.csv</strong> Area
 (m<sup>2</sup>) and canopy data (as Global Site Factor, see
 data description) for each pond. Dataset is 3 columns x 65 rows.