Small mammal densities were estimated from small mammal recapture data in burned and unburned grassland.
Web trapping design:
Experimental units were established in a 4 x 4 grid as part of a burn and antelope exclosure experiment. Small mammals were trapped in fireblocks 1, 2, 3, and 4. Each fireblock contains four webs, for a total of 16 webs. Small mammal densities are estimated from recapture data.Within each location four webs were established. Each web contains twelve 100m transects radiating from a central point in a spoke like fashion. Four "Sherman" traps were placed around this central point. Twelve traps are placed along each of the radiating lines, the first four are placed at 5m intervals, and the remaining eight placed at 10m intervals. Rebar were used to mark the location of trap placement. Each rebar was tagged with a number from 1 to 145, with trap number 1 at the north facing spoke and radiating out to trap number 12, with each spoke following with successive numbers increasing in a clockwise fashion. Trap number 145 includes the four traps placed in the center of the web. Traps were placed adjacent to rebar unless a shaded area could be found within a meter or so along an arc of equal radius from the center. The webs are separated by distances from approx. 100m to 600m. Within each fireblock, each web is marked with a number from 1-4.Trapping times:Each summer was divided into two periods: period 1 and period 2.Mammals were trapped as follows:1991: period 1: NA period 2: September 4 - October 41992: period 1: April 15 - May 8 period 2: August 4 - September 171993: period 1: April 6 - 29 period 2: September ??Each location was trapped in the same order for each period.The order is as follows:1. Fireblock 12. Fireblock 23. Fireblock 34. Fireblock 4Each trapping session consisted of placing and baiting traps on Monday, then checking the traps at dawn on both Tuesday (night 1), Wednesday (night 2), and Thursday (night 3). The traps were collected on Thursday after being checked for animals. A small handful of rolled oats was placed into each trap, with small amounts placed outside trap door. Animals were removed form closed traps with the aid of plastic bags. They were then identified to species. Weight was determined to the nearest gram using a pesola scale. Body, tail, foot, and ear measurements were taken for Peromyscus. Body and tail measurements were taken for Onychomys, Perognathus, and Reithrodomtomys. All measurments were taken to the nearest millimeter using a plastic ruler. Reproductive status was determined by examination of the genitalia. The animal was also sexed, aged, and marked. Marking was done to each animal on the first nights capture for each individual animal.
File created by Susan McKelvey 3/29/93. File supplemented by Rosemary Vigil 24 June 1993. Checked Oct 20, 1995; James Brunt
Data Entry1. Data were entered at Biology Annex using data entry program "mammal-entry"2. Data were checked for errors by comparing original data sheets with the data entered into the computer.3. After all errors were corrected, a dbf file was created using a Sun machine. (/research/local/mammal/bin/SASmam2dbf filename > filename.dbf) This modifies the comments, leaving out comments noted as "na".4. A rdb file was then created using "arc2rdb filename.dbf > filename.rdb".5. The rdb file was then checked for errors using "check < filename.rdb".6. After errors were corrected, the rdb file was sorted using "sort filename | uniq -c | page" to check that every entry was unique.7. Duplications were investigated and corrected.8. Dbf and rdb files were then copied to /research/archive/dbwork/vertebrate/ mammal/burnplot9. From sevilleta, at burnplot>, the rdb file was run through a program called webDist to create an input file as such: " webDist filename.rdb location period > conventional input name. (naming conventions: site-season-year.in)10.Input file was copied into /research/archive/dbwork/vertebrate/mammal/ burnplot11.From a PC, the input file was run through a distance program in order to get densities. (from dos: L:, cd distance, dist i=L:\burnplot/filename.in o=L:\burnplot\filename.out)12.Densities were cbtained from the output file and put into /mammal/data/ density-data/mammal_densities.data.burn which is a table containing the following: year season location web n density stderr cv lcl ucl. 13.At this point, nothing further has been done.