Abstract:

Marsh rice rats were captured during April-June in 2013-2017 at four oiled and three unoiled sites in southeastern Louisiana. Animals were trapped using Sherman live traps and tagged with ear tags and/or PIT tags (PIT tags were added during the 2017 field season and were only applied to adult animals weighing over 30g). The mark-recapture dataset contains capture information (location, tag numbers) and encounter history over three consecutive trap nights. The abundance dataset contains derived estimates and statistical information calculated in the software program MARK, which provides parameter estimates (e.g. abundance) based on mark-recapture data.

Suggested Citation:

Perez-Umphrey, Anna, Taylor, Sabrina, Stouffer, Phillip. 2019. Mark-recapture and estimated abundance data of marsh rice rats (Oryzomys palustris) trapped on oiled and unoiled plots in Plaquemines Parish, Louisiana from 2013-04-07 to 2017-06-10. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/n7-c7zj-xe50

Purpose:

Mark-recapture datasets are commonly used to estimate demographic parameters of free-ranging species. We estimated the abundance of marsh rice rats in salt marshes affected by the 2010 Deepwater Horizon oil spill by repeatedly trapping at the same sites and tagging captured animals.

Data Parameters and Units:

The file RiceRat_Mark-Recapture_2013-2017_sub1.xlsx: Data is organized by individual sites and dates of an encounter, by year. Year of Trapping: YYYY; Field Site Name: User-defined site identifier; Center of plot-latitude: The latitude of the center of the sampling site in decimal degrees; Center of plot-longitude: The longitude of the center of the sampling site in decimal degrees; Treatment type: Site condition based on SCAT map criteria: oiled (heavily oiled), unoiled (very light or no oil observed); Ear Tag ID: Unique numerical identifier of the tags placed on the right and/or left ears. NA = no ear tag present. Note: tags were placed on only one ear in 2013, both ears in 2014-2016, and in 2017 (when PIT tags began to be deployed) in individuals less than 30g; PIT Tag ID: Unique alphabetical/numerical identifier of the tag placed subcutaneously between the shoulder blades. NA = no PIT tag present (PIT Tags were deployed only in 2017); Collection ID: Unique identifier given to an animal that died during handling but was a new capture (i.e. had no other ID). NA = not applicable. Encounter History-DAY 1: Date of first day of sampling (DD-MM-YY) and whether an animal was captured on this day (1=presence, 0=absence); Encounter History-DAY 2: Date of second day of sampling (DD-MM-YY) and whether an animal was captured on this day (1=presence, 0=absence); Encounter History-DAY 3: Date of third day of sampling (DD-MM-YY) and whether an animal was captured on this day (1=presence, 0=absence); Trap-induced Mortality: Whether an animal died during handling or not (minus 1=died, 1=did not die). The file RiceRat_Derived_Estimates_2013-2017_sub1.xlsx: Year (YYYY); Site (User-defined site identifier for four oiled and three unoiled sites; O2, O3, O4, O6, U1, U2, U4); Annual derived abundance estimates; standard error and confidence intervals for rice rats calculated by the MARK software program. NA = not applicable.

Methods:

Marsh rice rats were trapped using Sherman live traps. If an individual was a recapture, that animal’s unique ear tag and/or PIT tag identification was recorded. If the individual was a new capture, it received either ear tags on one ear (2013 field season), both ears (2014-2016 field seasons), or if it was an adult over 30g, a PIT tag (the 2017 field season). PIT tags were implanted subcutaneously between the shoulder blades using a spring-loaded implanter and 12-gauge needles. All animals were scanned using a PIT tag reader to detect any implanted tags. Data was analyzed in Program MARK under a Huggins closed capture model. Twelve candidate models were considered where capture probability (p) varied by treatment, time, or site, and recapture probability (c) varied by time. Years were analyzed separately and the best fit model for each year was used to derive estimates of marsh rice rat abundance at each site.

Instruments:

Sherman live traps were used to trap marsh rice rats 1cm ear tags: 1005-1, National Band and Tag, Co. Ear tag applicator: 1005s-1, National Band and Tag, Co. PIT tag implanter: MK10 implanter, Biomark, Inc. PIT tags: FDX-B HPT12, Biomark, Inc. PIT tag reader: Biomark 601 Reader, Biomark, Inc.

Individual Files: