DOI: 10.5061/dryad.2280gb61c
title: Data from: Colorado aquatic macroinvertebrate samples and duck counts

description: Food availability varies considerably over space and time in wetland
 systems, and consumers must be able to track those changes during nutrient
 demanding points in the life cycle like breeding. Resource tracking has
 been studied frequently among herbivores, but receives less attention
 among consumers of macroinvertebrates. We evaluated the change in resource
 availability across habitat types and time, and the simultaneous density
 of waterfowl consumers throughout their breeding season in a
 high-elevation, flood-irrigated system. We also assessed whether the
 macroinvertebrate resource density better predicted waterfowl density
 across habitats, compared to consistency (i.e., temporal evenness) of the
 invertebrate resource or taxonomic richness. Resource density varied
 marginally across wetland types but was highest in basin wetlands (i.e.,
 ponds) and peaked early in the breeding season, whereas it remained
 relatively low and stable in other wetland habitats. Breeding duck density
 was positively related to resource density, more so than temporal resource
 stability, for all species. Resource density was negatively related to
 duckling density, however. These results have the potential to not only
 elucidate mechanisms of habitat selection among breeding ducks in
 flood-irrigated landscapes, but also suggest there is not a consequential
 trade-off to selecting wetland sites based on energy density versus
 temporal resource stability and that good-quality wetland sites provide
 both.
description: <em>Macroinvertebrate Data Collection</em>
 We collected nektonic invertebrate samples using 2-L activity
 traps in 2020 and 2021 (Murkin et al. 1983). We placed traps at
 randomly-selected points within 40 wetland sites that encompassed the five
 different wetland habitats. The sites we sampled in four of the wetland
 habitats (basin wetlands, riparian wetlands, irrigation ditches, and
 flooded hay meadows) spanned three individual properties, including two
 private ranches and Arapaho NWR (Figure 1). We also sampled three public
 reservoirs across the study area. We selected three random wetlands of
 each type on each of the three properties, and three random sampling
 points within each selected wetland with the exception of reservoirs. We
 randomly selected two 200-m length plots of shoreline in each reservoir
 and three random points within each plot to sample (Cooper and Anderson
 1996, de Szalay et al. 2003, Behney 2020). In total, we deployed 126 traps
 during each sampling occasion (3 properties x 4 wetland habitats x 3
 sampled wetland sites of each variety x 3 sampled points in each wetland)
 = 108 samples, + (3 reservoirs x 2 plots in each reservoir x 3 points in
 each plot = 18 samples). Traps remained in the wetlands for 48 hours every
 fourteen days, resulting in six sampling occasions each year over the
 course of the breeding season (13 May through 22 July). No traps were
 placed if the wetland was dry on a given sampling occasion, and that
 status was noted and aquatic invertebrate resource density was treated as
 a zero for that occasion. In the event that a wetland was not flooded or
 less flooded during the second year of sampling (2021), we randomly
 selected new points within the new boundary of the same wetland and
 treated those sampling points as unique from the original locations, but
 nested within the same site. Occasionally traps became dislodged and
 either went missing or floated to the surface, in which case we replaced
 traps and allowed them to remain in the wetland for the subsequent 48
 hours. Activity traps had a 15 cm opening at the widest
 part of the funnel and a 2 cm opening at the narrowest part of the funnel.
 We placed them so that the top of the widest part of the funnel was
 approximately 1 cm above the surface of the water to capture invertebrates
 in the part of the water column in which dabbling ducks most often forage
 (Guillemain et al. 2000, Behney 2020). Upon collection, traps were emptied
 into a mesh sieve-bottom bucket. All individual invertebrates from the
 sample were placed into plastic storage cups and stored in 70% ethanol
 until processing. We emptied each sample into a 0.355 mm (number 45) gauge
 mesh sieve in a wet lab and moved all individuals to a Petri dish for
 identification and counting (Behney 2020). We placed samples under a
 dissecting microscope (AmScope SM-1BSY-64S Stereo Zoom Microscope) and
 identified individuals to taxonomic Family when possible. Any sample
 containing more than 1000 individuals of a given Family was subsampled by
 16.6% using a 6 x 6 square gridded Petri dish (Williams et al. 2014,
 Behney 2020). We counted individuals in a random subset of six of the 36
 cells and multiplied by six to estimate the total number of individuals of
 that Family in the sample. <em>Waterfowl Data
 Collection</em> We conducted breeding pair counts
 of ducks on the same wetland sites being sampled for macroinvertebrates
 (n=40) using a dependent double-observer methodology during the breeding
 seasons of 2020 and 2021 (Nichols et al. 2000). Pair count survey timing
 coincided with the first three macroinvertebrate sampling occasions. A
 primary observer counted every individual dabbling and diving duck
 observed and reported the number to a secondary observer, who recorded
 data while also recording any observations missed by the primary observer
 (Roy et al. 2021). We restricted the dataset to the four most common
 species of breeding ducks in our study system, which included cinnamon
 teal (<em>Spatula cyanoptera</em>), gadwall (<em>Mareca
 strepera</em>), mallard (<em>Anas platyrhynchos</em>),
 and lesser scaup (<em>Aythya affinis</em>). Although we used
 the standard pair count practice of separating lone drakes from paired
 ducks in each count to identify breeding phenology and thus the timing of
 our first invertebrate sampling occasion, we used the total count of
 breeding ducks for the purposes of evaluating the relationship between
 duck density and invertebrate availability. In addition, few individuals
 were missed by the primary observer (i.e., detection probability was
 high), so we pooled observed drakes and hens of a given species to give us
 a site- and occasion-specific count. Brood surveys also
 occurred on the sites sampled for macroinvertebrates, but followed an
 independent double-observer methodology during 2020-2021 (Nichols et al.
 2000, Vrtiska and Powell 2011). Both observers counted the number of
 ducklings they observed and subsequently compared observations to
 determine whether they had been observing the same brood and compare the
 number counted. The smaller number of ducklings commonly observed at one
 time allowed for accurate count comparisons between observers (Pagano and
 Arnold 2009). The timing of counts coincided with the latter three
 macroinvertebrate sampling occasions. Observers counted all ducklings
 within a given brood and identified their age class according to Gollop
 and Marshall (1954). Observers spent a minimum of ten minutes at each
 wetland site and conducted surveys using window- or tripod-mounted
 spotting scopes and binoculars to allow time for hidden broods to become
 visible (Pagano and Arnold 2009, Walker et al. 2013). We restricted the
 dataset to ducklings of the same four duck species listed above, and
 pooled the total number of ducklings for a given species, site, and
 occasion.
description: # North Park, Colorado aquatic macroinvertebrate samples and duck counts
 [https://doi.org/10.5061/dryad.2280gb61c](https://doi.org/10.5061/dryad.2280gb61c) Aquatic invertebrate data sampled from North Park, Colorado in 2020 and 2021 and corresponding duck/duckling counts conducted simultaneously. ## Description of the data and file structure ID: unique sampling location within a site site: anonymized wetland site of a given habitat type within a property habitat: wetland type (irrigation ditch, hay meadow, basin wetland, reservoir, or riparian) week: sampling occasion  year: 2020 or 2021 property: anonymized landownership - indicates general area of wetland samples dry: whether the wetland was dry when sampled (1=dry, 0=flooded) do: dissolved oxygen (%) temp: temperature (degrees Celsius) cond: conductivity (µS/cm) richness: total number of taxonomic groups of invertebrates found within a sample total.inverts: total number of individuals within a sample across taxonomic groups energy: KJ per trap j.cm3: Joules per cubic cm in a trap size_ha: size of the wetland in ha nducks_total: total number of ducks or ducklings observed of all species nducks_sp: number of ducks or ducklings observed of a given species during the referenced count prop_count: proportion of the total number of ducks or ducklings observed represented by the species in that line duck_density: nducks_sp divided by the size of the wetland (ha) eq: EQ metric described in the manuscript indicating the temporal evenness of energy density Columns K-AL: correspond to the number of individuals found in a sample of a given taxonomic group of invertebrates (column names) Column names are the same across csv files and site, property, and habitat match across files. NA in the dataset indicates missing data