Surveying Cory Shearwater colonies with camera traps and identifying potential invasive nest predators

Abstract Background The Azores holds the largest population of Cory's shearwater Calonectrisborealis (Cory, 1881) (Aves, Procellariiformes, Procellariidae) in the world. One of the major threats of this species in the Azores is the predation by invasive mammals, which were introduced during European colonisation of the islands. The present study provides a dataset from a camera-trapping survey performed in colonies of Cory’s shearwater. The sampling was conducted between 7 April and 23 October 2019, covering the entire breeding season, in three colonies of the Terceira Island (Azores). A total of 32 nests were sampled using motion-triggered cameras. The aims of this study are to provide information about the ecological patterns of the Cory shearwater and to identify potential nest predators. New information Our results include a total of 6972 records of 15 species (nine species of birds, five of mammals and one reptile), of which 5414 records are of Cory’s shearwater, 478 of potential mammal predators and 1080 of another vertebrate species. Information about the biology of the species is also provided, as species circadian behaviour and habitat description.

The present study provides a dataset from a camera-trapping survey performed in colonies of Cory's shearwater.The sampling was conducted between 7 April and 23 October 2019, covering the entire breeding season, in three colonies of the Terceira Island (Azores).A total of 32 nests were sampled using motion-triggered cameras.The aims of this study are to provide information about the ecological patterns of the Cory shearwater and to identify potential nest predators.

Introduction
Biological invasions, climate change and habitat fragmentation, degradation and destruction are the main drivers of biodiversity loss worldwide (e.g.Vitousek et al. (1997), Bellard et al. (2014), Doherty et al. (2016)).These three biodiversity erosion drivers can act synergistically, but invasive species alone can affect dramatically the native species communities and ecosystems functioning (e.g.Capizzi ( 2020)).In comparison with mainland areas, island ecosystems are especially vulnerable to biological invasions (Blumstein and Daniel 2005, Bellard et al. 2014, Spatz et al. 2017).Mammal predators constitute an important threat to island native vertebrates, being responsible by the decline or extinction of hundreds of island species worldwide (Medina et al. 2014, Dawson et al. 2014, Doherty et al. 2016).Island terrestrial and marine birds have been particularly affected by the introduction of invasive mammals (Medina et al. 2014, Spatz et al. 2017).
The Azores Archipelago comprises nine main islands of volcanic origin and it is located in the North Atlantic Ocean.The islands are considered a high priority area for seabird conservation, harbouring important populations of many seabird species, as for example, the globally endangered Monteiro's storm-petrel Hydrobates monteiroi Bolton et al. 2008(Bolton et al. 2008, BirdLife-International 2016) or the Cory's shearwater Calonectris borealis (Cory, 1881), for which the Azores population is one of the largest worldwide.
Studies about seabirds and terrestrial birds' populations in the Archipelago showed that mammal predators are probably the main cause of breeding failure (Monteiro et al. 1996, Amaral et al. 2010, Hervías et al. 2013a, Hervías et al. 2013b, Lamelas-López et al. 2020, Lamelas-López et al. 2021) or extinction (Monteiro et al. 1996).Mammals were introduced in the Archipelago as a consequence of the Portuguese arrival and settlement in the 15 century.Currently, the mammal predators present in the Archipelago include rodents (house mouse Mus musculus Linnaeus, 1758, black rat Rattus rattus Linnaeus, 1758 and Norway rat Rattus norvegicus Berkenhout, 1769) and carnivores (ferret Mustela furo Linnaeus, 1758, weasel Mustela nivalis Linnaeus, 1766, feral cat Felis silvestris catus Schreber, 1775 and feral dog Canis lupus familiaris Linnaeus, 1758).th Identification of predators and the knowledge about their ecological patterns are crucial to the conservation of native terrestrial and marine birds of the Azores (Rader et al. 2007, Richardson et al. 2009).In this context, camera-trapping has been demonstrated to be an efficient tool to answer a variety of research questions in the fields of animal ecology, behavioural studies and conservation biology or for the inventory and monitoring of wildlife (Tobler et al. 2008, O'Connell et al. 2011, Rendall et al. 2014), particularly applied to identify invasive predators and to assess their impacts on native biodiversity (Oppel et al. 2014, Lamelas-López et al. 2020, Lamelas-López et al. 2021).

General description
Purpose: The main objectives of this study are to provide a dataset of species present in three Cory Shearwater colonies of Terceira Island, obtained from camera-trap records; and to obtain information about the biology of the Cory Shearwater, through the description of habitat and circadian behaviour and to identify potential introduced mammal predators.

Project description
Title: Surveying seabird colonies with camera traps: The impacts of invasive predators on Cory Shearwater Personnel: Lucas Lamelas-López, Paulo A.V. Borges
Design description: Motion-triggered infrared cameras (Bushnell Trophy HD, Moultrie 880i and 990i) were installed in the colonies at the beginning of the breeding season (e.g.Lamelas-López et al. (2020)).We installed one camera per nest, which remained recording continuously until the end of the breeding season or until the nest was abandoned or depredated and then the camera was moved to another nest.The cameras were deployed at 50-100 cm of the nest entrances.Cameras were configured to take 8 MB-photos, with 30 seconds of delay between them (Lamelas-López et al. 2021).Date and time were automatically recorded for each event.The nests were monitored each 10 days, in order to assess the nest condition and to replace the SD cards and the batteries of the cameras, if necessary.The study was conducted from 7 April and 23 October 2019.The obtained photos were posteriorly analysed and identified by L.L.L.
Sampling description: Motion-triggered infrared cameras (Bushnell Trophy HD, Moultrie 880i and 990i) were installed in the colonies at the beginning of the breeding season (e.g.Lamelas-López et al. (2020)).We installed one camera per nest, which remained recording continuously until the end of the breeding season or until the nest was abandoned or depredated and then the camera was moved to another nest.The cameras were deployed at 50-100 cm of the nest entrances.Cameras were configured to take 8 MB-photos, with 30 seconds of delay between them (Lamelas-López and Salgado 2020, Lamelas-López et al. 2021).Date and time were automatically recorded for each event.The nests were monitored each 10 days, in order to assess the nest condition and to replace the SD cards and the batteries of the cameras, if necessary.The study was conducted from 7 April and 23 October 2019.The obtained photos were posteriorly analysed and identified by L.L.L.
Quality control: All the photos were carefully verified by the authors.
Step description: Between 7 April and 23 October 2019, a total of 32 camera-traps were installed in three of Cory's shearwater colonies on Terceira Island, covering the entire breeding period.We searched occupied nests and installed one camera per nest, which remained recording continuously until the end of the breeding season or until the nest was abandoned or depredated and then the camera was moved to another nest.Cameras were deployed at 50-100 cm of the nest entrance and were programmed to take photos, which recorded date and time of the event.Nests were monitored each 10 days, in order to assess the nest condition and to replace the SD cards and batteries of the cameras.The obtained photos were posteriorly analysed and identified by L.L.L.
The data have been published as a Darwin Core Archive (DwC-A), which is a standardised format for sharing biodiversity data as a set of one or more data tables.We provided an event data table, which contains 2976 records; and an occurrence data table, with 6972 records.
Coordinates: 3843'17"N Latitude; 27°13'14"W Longitude and .scientificNameAuthorship Name of the author of the lowest taxon rank included in the record.

Additional information
A total of 6972 records of vertebrates were obtained, belonging to three classes, seven orders, 11 families and 15 species ( Most abundant mammal species were rodents R. rattus (n = 294) and M. musculus (n = 110) and the domestic cat (n = 68).These species were detected in all C. borealis colonies and they are known predators of terrestrial birds and seabirds in many islands worldwide (Bolton et al. 2008, Medina et al. 2014;Spatz et al. 2017) and particularly in the Azores islands (Monteiro et al. 1996, Hervías et al. 2013a, Hervías et al. 2013b, Lamelas-López et al. 2020, Lamelas-López et al. 2021;Fig. 1).M. nivalis has also been reported has a potential predator of native birds in the Archipelago, but our data suggest that the impact will be probably low (we only recorded four events in one colony).
Teira dugesii was detected in the colonies (n = 298), mainly in the Chanoca colony, which is dominated by rocky areas.
Additionally, in the dataset, we also provided information about the behaviour of the species, particularly of the circadian activity of the species.Calonectris borealis demonstrated to be more active during the dawn and dusk (n = 1738 records) and night (n = 3235 records), in comparison with day (n = 441 records).In general, introduced mammal predators were also more frequently observed during these periods.For example, R. rattus was mainly detected during the night (n = 217) or crepuscule (n = 64) in comparison with the day (n = 13).However, the F. catus was detected during all of the day (crepuscule n = 26, night n = 21, day n = 21).
Identification of introduced predator species and information of their abundance, habitat preferences or behaviour are crucial for information to design effective management plans and conservation actions (Thompson 2007, Lamelas-López et al. 2020).

Figure 1 .
Figure 1.Record of Felis catus predating on a chick of Calonectris borealis in Chanoca colony.
The following Classes and Orders are covered: Aves: Procellariiformes, Columbiformes, Passeriformes; Mammalia: Carnivora, Lagomorpha, Rodentia; Reptilia: Squamata.Surveying Cory Shearwater colonies with camera traps and identifying potential ... The dataset is available on the Global Biodiversity Information Facility platform, GBIF (Lamelas-López and Borges 2023).The following data table includes records at species level.The dataset submitted to GBIF is structured as a sample event dataset, with two tables: event and occurrence tables.The data in this sampling event resource have been published as a Darwin Core Archive (DwCA), which is a standardised format for sharing biodiversity data as a set of one or more data tables.The event table contains 2976 records.This IPT (Integrated Publishing Toolkit) archives the data and, thus, serves as the data repository.The data and resource metadata are available for download from Lamelas-López and Borges (2023).and, thus, serves as the data repository.The data and resource metadata are available for download from Lamelas-López and Borges (2023).
Description: Data set name: Event Table Character set: UTF-8 Download URL: http://ipt.gbif.pt/ipt/resource?r=camera-trap_seabirds_2023Data format: Darwin Core Archive Data format version: version 1.2 Description: geodeticDatum The ellipsoid, geodetic datum or spatial reference system (SRS) upon which the geographic coordinates given in decimalLatitude and decimalLongitude are based.coordinateUncertaintyInMeters Uncertainty of the coordinates, in metres.Data set name: Occurrence Table Character set: UTF-8 Download URL: http://ipt.gbif.pt/ipt/resource?r=camera-trap_seabirds_2023Data format: Darwin Core Archive event resource have been published as a Darwin Core Archive (DwCA), which is a standardised format for sharing biodiversity data as a set of one or more data tables.The occurrence table contains 6972 records.This IPT (Integrated Publishing Toolkit) archives the data establishmentMeans The process of establishment of the species in the location, using a controlled vocabulary: 'native', 'introduced', 'endemic', 'Macaronesian native'.occurrenceStatus Information about the presence/absence of a taxon at a camera location.eventID Identifier of the events, unique for the dataset.taxonRank Lowest taxonomic rank of the record.