This document was generated on 2022-02-17 by Mariana A. Campbell. GENERAL INFORMATION 1. Title of Dataset: "Dietary shifts may underpin the recovery of a large carnivore population". 2. Author Information A. Principal Investigator Contact Information Name: Mariana A. Campbell Institution: Charles Darwin University Address: Ellengowan Drive, Casuarina NT 0909 Australia Email: mariana.campbell@cdu.edu.au B. Associate or Co-investigator Contact Information Name: Hamish A. Campbell Institution: Charles Darwin University Address: Ellengowan Drive, Casuarina NT 0909 Australia Email: hamish.campbell@cdu.edu.au 3. Date of data collection (single date, range, approximate date): 2016 4. Geographic location of data collection: North-western areas of theNorthern Territory, Australia. 5. Information about funding sources that supported the collection of the data: This work was supported by the Australian Research Council (Project ID: DP210103369). SHARING/ACCESS INFORMATION 1. Licenses/restrictions placed on the data: None 2. Links to publications that cite or use the data: Campbell et al., 2022. Campbell, M.A., Udyawer, V., Jardine, T.D., Fukuda, Y., Kopf, R.K., Bunn, S.E., Campbell, H.A. (2022) Dataset: Dietary shifts may underpin the recovery of a large carnivore population. Biology Letters. In review. 3. Links to other publicly accessible locations of the data: NA 4. Links/relationships to ancillary data sets: NA 5. Was data derived from another source? Yes, only for part of the data, which source is listed as "Adame et al., 2018". A. If yes, list source(s): Source: Adame MF, Jardine TD, Fry B, Valdez D, Lindner G, Nadji J, et al. (2018) Estuarine crocodiles in a tropical coastal floodplain obtain nutrition from terrestrial prey. PLoS ONE 13(6): e0197159. https://doi.org/10.1371/journal. 6. Recommended citation for this dataset: Campbell, M.A., Udyawer, V., Jardine, T.D., Fukuda, Y., Kopf, R.K., Bunn, S.E., Campbell, H.A. (2022) Dataset: Dietary shifts may underpin the recovery of a large carnivore population. Biology Letters. DATA & FILE OVERVIEW 1. File List: [BiologyLetters_Campbell_etal_2022_rawdata_dryad.csv] 2. Relationship between files, if important: NA 3. Additional related data collected that was not included in the current data package: NA 4. Are there multiple versions of the dataset? No METHODOLOGICAL INFORMATION Estuarine crocodile bone samples were collected from north-western areas of the Northern Territory (Australia) between Darwin Harbour and the East Alligator River (~300km apart). Historical bone samples were collected from the Museum and Art Gallery of the Northern Territory (MAGNT, Darwin, NT, Australia). Those bones were from crocodiles caught and killed between 1968 and 1986 from various parts of the Northern Territory (n = 22). Some crocodiles were very large and were likely older than 50 years of age upon death. Sampled crocodile bones were from animals with total body lengths ranging between 120 and 513 cm. The sampled bones were not treated or preserved and cleaned by macerating the bones in water. Samples were taken from the left front leg humerus. First, an ~ 0.2 mm outer bone layer was scraped away using a scalpel, and then ~ 0.2 g of bone was scraped out and placed in a sample vial for the analysis.  The contemporary cohort of bone samples was collected from crocodiles trapped and removed from around Darwin as part of the crocodile management program in 2016. These crocodiles ranged from 115 to 330 cm total body length (n = 24). A small section from the left humerus bone was removed and prepared as the museum specimens. The bones were not acidified prior to analysis as carbonate removal has been shown to have minimal effect upon reptile bone δ13C, but instead a correction factor was used (Turner Tomaszewicz et al., 2015). The mean C/N ratios for the bone samples was 3.4 ± 0.2 S.D. (range = 3.1 to 4.3), and only 3 out of 48 samples had C/N ratios above a proposed threshold of 3.6 for intact collagen. Bone samples from both cohorts were freeze-dried at -40ºC (Dynavac Freeze Dryer) for 48h and then homogenised to a fine powder using an electric ball-mill grinder (RETSCH Mixer Mill MM400). A small sub-sample from each was weighed (0.8 – 1.0 mg) into tin capsules and analysed for stable isotopes (δ13C and δ15N) at the Stable Isotope Core Laboratory at Washington State University (WA, USA). The δ13C and δ15N values from those bone samples were corrected using diet-tissue discrimination factors (1.4 ‰ and 3.0 ‰, respectively). The carbon isotope values were corrected for the Suess effect by deducting 0.4 ‰ from the “historic” cohort. Body size is known to influence δ13C and δ15N values in crocodilians. Our “contemporary” cohort had a reduced range of body sizes compared to the “historic” cohort. To provide a more comparative range of body sizes, we sourced additional stable isotope values from Adame et al., 2018. These estuarine crocodiles (n = 41, size range = 83.5 to 420 cm) were captured from the same region between 2012 and 2014 (details on scute tissue isotopic discrimination in Adame et al., 2018). We first tested if it was a valid assumption to combine these two groups of crocodiles, whose collagen had been sampled from different tissues (bone and scute). REFERENCES: Turner Tomaszewicz, C.N., Seminoff, J.A., Ramirez, M.D. & Kurle, C.M. 2015 Effects of demineralization on the stable isotope analysis of bone samples. Rapid Communications in Mass Spectrometry 29, 1879-1888. Adame MF, Jardine TD, Fry B, Valdez D, Lindner G, Nadji J, et al. (2018) Estuarine crocodiles in a tropical coastal floodplain obtain nutrition from terrestrial prey. PLoS ONE 13(6): e0197159. DATA-SPECIFIC INFORMATION FOR: [BiologyLetters_Campbell_etal_2022_rawdata_dryad.csv] 1. Number of variables: 8 2. Number of cases/rows: 88 3. Variable List: d13C: raw isotopic values for δ13C (prior to the correction factor, subtraction of discrimination factor, and correction for Suess effect, see Methodology for details). d15N: raw isotopic values for δ15N (subtraction of discrimination factor, see Methodology for details). TL_cm: crocodile total body length (cm) cohort: experimental group site: location where crocodile sample was originated from, all within the NT, Australia Year_received_MAGNT: Year the crocodile skeleton was received by the Museum and Art Gallery of the Northern Territory (MAGNT) Year_tissue_collection: Year of tissue sample collection source: Tissue/Data source 4. Missing data codes: NA 5. Specialised formats or other abbreviations used: NA