Details and raw isotope data for samples related to a semi-controlled feeding study involving rats fed to a red-tailed hawk (Buteo jamaicensis) and Eurasian eagle owl (Bubo bubo).

Rationale: We investigated isotopic diet-excreta offset (Ddiet-excreta) for predatory birds, and the isotopic influence of bird digestion on consumed prey tissues. The foraging ecology of predatory birds can be non-invasively monitored using excreta or regurgitated prey. However, one must account for Ddiet-excreta and any influence of digestion on prey tissues. Neither of these has been previously evaluated for predatory birds.
Methods: We worked with a captive Eurasian eagle owl (Bubo bubo) and red-tailed hawk (Buteo jamaicensis) fed frozen rats. We collected rat feet, as well as regurgitated pellets and excreta from each bird’s enclosure. We analyzed carbon (d13C) and nitrogen (d15N) isotopes in undigested rat muscle, undigested and digested fur and bone collagen (extracted from pellets); d13C, oxygen (d18O), and strontium (87Sr/86Sr) isotopes in rat bone bioapatite; and d13C, d15N and 87Sr/86Sr in bird excreta.
Results: Diet-excreta offset differed slightly between individuals, ..., This dataset summarizes raw isotope data for rat tissues before and after digestion by Rhett, the red-tailed hawk, or Caspian, the eagle owl, who were individually housed at the Cincinnati zoo. We have also included isotope data for excreta produced by the birds. The study was conducted for a total of 11 days. A foot from each consumed rat was collected before feeding the birds, and then a regurgitated casting and excreta sample were collected from each bird's enclosure the following day. 
Rat collagen was isolated by soaking samples in 0.5 N HCl at 4°C ultil they were demineralized, rinsing in ultrapure water five times. Lipids were removed from rat muscle, hair and bone by sonicating samples in trace metal grade petroleum ether 2 to 5 times, then sonicating in ultra pure water 2 to 5 times, and drying.
Rat bioapatite was processed by soaking powdered sample in 30% H2O2 for 72 hours, rinsing with ultrapure water five times, soaking in 1 M Acetic Acid buffered with calcium acetate,..., , # Details and raw isotope data for samples related to a semi-controlled feeding study involving rats fed to a red-tailed hawk (Buteo jamaicensis) and Eurasian eagle owl (Bubo bubo).

[https://doi.org/10.5061/dryad.ksn02v7ft](https://doi.org/10.5061/dryad.ksn02v7ft)

## Description of the data and file structure

### Files and variables

#### File: Dryad\_dataset.xlsx

**Description:** 

This dataset summarizes raw isotope data for rat tissues before and after digestion by Rhett, the red-tailed hawk, or Caspian, the eagle owl, who were individually housed at the Cincinnati zoo. We have also included isotope data for excreta produced by the birds. The study was conducted for a total of 11 days. A foot from each consumed rat was collected before feeding the birds, and then a regurgitated casting and excreta sample were collected from each bird's enclosure the following day. 

Within the dataset, blank cells indicate analyses that were not performed for specific samples. No data were exclud...,