Data from: DNA metabarcoding reveals the broad and flexible diet of a declining aerial insectivore

Aerial insectivores are highly mobile predators that feed on diverse prey items that have highly variable distributions. As such, investigating the diet, prey selection, and prey availability of aerial insectivores can be challenging. In this study, we used an integrated DNA barcoding method to investigate the diet and food supply of Barn Swallows, an aerial insectivore whose North American population has declined over the past 40 years. We tested the hypotheses that Barn Swallows are generalist insectivores when provisioning their young and select prey based on size. We predicted that the diets of nestlings would contain a range of insect taxa but would be biased towards large prey items and that the diet of nestlings would change as prey availability changed. We collected insects using Malaise traps at ten breeding sites and identified specimens using standard DNA barcoding. The sequences from these insect specimens were used to create a custom reference database of prey species and their relative sizes for our study area. We identified insect prey items from nestling fecal samples by using high-throughput DNA sequencing and comparing the sequences to our custom reference database. Barn Swallows fed nestlings prey items from 130 families representing 13 orders but showed selection for larger prey items that were predominantly from seven dipteran families. Nestling diet varied both within and between breeding seasons as well as between breeding sites. This dietary flexibility suggests that Barn Swallows are able to adjust their provisioning to changing prey availability on the breeding grounds when feeding their nestlings. Our study demonstrates the utility of custom reference databases for linking the abundance and size of insect prey in the habitat with prey consumed when employing molecular methods for dietary analysis

Does prey availability affect the reproductive performance of Barn Swallows (Hirundo rustica) breeding in Ontario, Canada?

Animal populations are often limited by food availability, particularly during the breeding season. In birds, food limitation can impact several components of the reproductive cycle, including the timing of reproduction and reproductive output. Barn Swallows (Hirundo rustica Linnaeus, 1758) have experienced a population decline over the past 40 years in North America that is thought to be related to changes in prey availability. We monitored Barn Swallow reproductive behaviour and prey availability throughout two breeding seasons at ten sites in Ontario, Canada to test the hypothesis that limited prey availability during the breeding season affected reproductive behaviour. We found no relationship between food availability and the number of eggs laid or the number of young fledged. Neither did we observe higher rates of second brooding or more pairs nesting at breeding sites with higher food availability. Barn Swallows did not time their reproductive effort to maximize prey availability during the nesting period, but any mismatch in phenology of prey and bird reproduction at a breeding site was not associated with lower reproductive success. The results of this study did not support our hypothesis and suggest that Barn Swallow reproductive behaviour was not negatively affected by limited prey availability on the breeding grounds.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Data from: Discrimination of grasshopper (Orthoptera: Acrididae) diet and niche overlap using next-generation sequencing of gut contents

Species of grasshopper have been divided into three diet classifications based on mandible morphology: forbivorous (specialist on forbs), graminivorous (specialist on grasses), and mixed feeding (broad-scale generalists). For example, Melanoplus bivittatus and Dissosteira carolina are presumed to be broad-scale generalists, Chortophaga viridifasciata is a specialist on grasses, and Melanoplus femurrubrum is a specialist on forbs. These classifications, however, have not been verified in the wild. Multiple specimens of these four species were collected, and diet analysis was performed using DNA metabarcoding of the gut contents. The rbcLa gene region was amplified and sequenced using Illumina MiSeq sequencing. Levins' measure and the Shannon–Wiener measure of niche breadth were calculated using family-level identifications and Morisita's measure of niche overlap was calculated using operational taxonomic units (OTUs). Gut contents confirm both D. carolina and M. bivittatus as generalists and C. viridifasciata as a specialist on grasses. For M. femurrubrum, a high niche breadth was observed and species of grasses were identified in the gut as well as forbs. Niche overlap values did not follow predicted patterns, however, the low values suggest low competition between these species

Illumina_Guts_Dryad_submitted_files

Illumina_Guts_Dryad_submitted_file

Conductivity, temperature, and depth measurements at the RMS Titanic wreck and Nargeolet-Fanning Ridge, Northwest Atlantic, in summer 2022

To gain information on the physical parameters of deep water in the Northwest Atlantic, CTD measurements were taken during seven dives to the RMS Titanic wreck (front of bow approx. 41.7330181, -49.9460561; 3816 m water depth) and one dive to the Nargeolet-Fanning Ridge (approx. 41.5980514, -49.4386889; 2896 m water depth) during the OceanGate expedition aboard the AHTS Horizon Arctic, 15 June - 25 July 2022. The CTD measurements of the water column down to a maximum water depth of 3853 m were conducted using a Valeport MIDAS SVX2 6000 unit attached to the submersible Titan for the duration of each dive and provided standard data for conductivity, temperature, and pressure. Conductivity and temperature data were used to compute salinity

Investigating suburban micromoth diversity using DNA barcoding of malaise trap samples

Micromoths can be challenging to identify based on morphology and are frequently omitted in assessments of moth diversity. However, their species richness and biology make them important components of terrestrial ecosystems. In this study we identified 1227 micromoths from a suburban garden at 63° north using DNA barcoding of Malaise trap samples. We recorded 78 different species with the 11 most abundant taxa accounting for 82 % of the catch. The remaining 67 species were represented by fewer than 14 specimens, but the number was often sufficient to provide a good idea of phenology. The larvae of these 78 species all feed on plants common in suburban environments. We show that when facilitated by identifications through DNA barcoding, Malaise traps provide interesting insights into the micromoth communities of suburban environments that might otherwise be overlooked. The use of Malaise traps is beneficial for investigations at high latitudes where light trapping is inefficient for sampling moths due to bright summer nights

Total alkalinity and dissolved inorganic carbon measurements at the RMS Titanic wreck and Nargeolet-Fanning Ridge, Northwest Atlantic, in summer 2022

To gain information on the chemical parameters of deep water in the Northwest Atlantic, water samples were taken using a Niskin bottle deployed at five stations at the RMS Titanic wreck site (stations: 0075, 0079, 0080, 0081, 0082 - deepest samples at station 0081: 41.7335576, -49.9467401, 3831 m water depth) and at one station at the Nargeolet-Fanning Ridge (station 0083: 41.5975604, -49.439188, 2870 m water depth) during the OceanGate expedition aboard AHTS Horizon Arctic, 15 June - 25 July 2022. A total of 20 water subsamples were collected and analysed for total alkalinity (TA) and dissolved inorganic carbon (DIC). TA was analysed using an Apollo SciTech AS-ALK2 alkalinity titrator and DIC was analysed using an Apollo SciTech AS-C3 inorganic carbon analyser. The aragonite saturation state was calculated using the CO2SYS system (Lewis and Wallace, 1998)