reversal trapline

CSM05 Seasonal summary of numbers of small mammals on the six LTER traplines in prairie habitats on which fire regime has been reversed at Konza Prairie


Data set contains seasonal summaries (spring and autumn) of the number of individuals of each species of small mammal captured (relative abundance) on each grassland trapline. Each record contains year, season, trapline and number of individuals captured of each species. These live trap records are based on daily captures during a single 4-day trapping period in spring (mid-March to early April) and autumn (late October to early December) for each of six permanent traplines established on two fire treatments (three traplines per treatment). These two fire treatments include one treatment that was changed from a 20-year burn to an annual burn and one that was changed from an annual burn to 20 years between fires. Bison do not graze these two habitat types.

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Determine temporal and spatial patterns of relative abundance of rodent and shrew populations and composition of assemblages of small mammals in tallgrass prairie as well as assess the effects of reversing fire regimes (from long-term unburned to annually burned and vice versa) on populations and communities of small mammals in contiguous fire treatments.


Location of Sampling Stations: Ungrazed, unburned: R20A; Ungrazed, annual burn: R01A

Frequency of Sampling: Both sites are sampled in autumn (late October to early December) and in spring (mid-March to early April).

Variable Measured: Numbers of individuals for each species of small mammal captured are recorded on each trapline. Sex, reproductive condition and capture location of each individual are recorded at each capture. Age, based on pelage characteristics, is recorded for the two species of Peromyscus at each capture. Body mass of an individual is recorded only at the first capture in each trapping period.

Methods, Traplines: Small mammals are trapped on three permanent traplines in both treatment units. Traplines A and B on each treatment consist of 20 stations with an inter-station distance of 15 m. Trapline C on each treatment has 10 stations with the same inter-station distance as traplines A and B. Because of the limitations of size of treatments and topography, our goal in this study was to have 100 trapnights within a treatment each night that we trapped. Stations 1, 5, 10, 15 and 20 on trapline A and B and stations 1, 5 and 10 on trapline C are marked with stakes of galvanized conduit. All stations are marked with fluorescent orange plastic surveyor flags at least once per year.

Trapping Procedures: Small mammals are trapped for 4 consecutive nights per trapline during each trapping period. Two large Sherman live traps (7.6 by 8.9 by 22.9 cm) are placed within 1 m of the surveyor flag or conduit at each station. Traps are baited with a mixture of high-quality creamy peanut butter (e.g., Jif) and oatmeal (Quaker old-fashioned oatmeal). The mixture is rolled into a small ball (1.5-2.0 cm in diameter) and wrapped in a 10-cm square of weighing paper. The bait is suspended in the trap by closing the back door of the trap on the twisted end of the weighing paper. Polyester fiberfill (5 g) is compressed by a #8 rubber band and used as nesting material in each trap in spring and autumn sampling periods. This nesting material reduces trap mortality in inclement weather. With the nest material and a large amount of bait in each trap, mammals typically are in good condition at the time that trap are checked in all types of weather. In the event that more than 50% of the traps are closed overnight without an individual captured (e.g., due to strong winds or other weather events such as heavy rain or deer licking traps), traps are set for additional nights until less than 50% of traps per night are closed without captures on that trapline.

All traps are checked early each morning, but after the end of the nocturnal activity period. All six traplines are run during the same 4-day trapping period. Generally, the reversal traplines are run after LTER core traplines and seasonal fire traplines in both seasons. Thus the amount of moonlight present during the trapping period is variable across seasons and years due to cloud cover and moon phase for the reversal traplines.

A battery-powered mustache clipper is used to clip a line of fur on each captured animals to indicate that that individuals has been captured in the current trapping period. The position clipped is dependent upon the trapline and occurs as follows: on the right shoulder (on R01A-A trapline in a spring sampling period), left shoulder (on R20A-A trapline in a spring sampling period), right rump (on R01A-A trapline in an autumn sampling period) and left rump (on R20A-A trapline in an autumn sampling period). For traplines B and C on each treatment area, the upper back is marked in an autumn sampling period and upper back in a spring sampling period. The reason for this difference in marking position is that the two A traplines are very close to each other and by marking the animals captured differently, we can determine if an individual has crossed the firebreak within a trapping period. Likewise, this method of marking allows an investigator to count an individual only once within a trapline during a trapping period. Further, three species of rodents (Peromyscus maniculatus, P. leucopus and Neotoma floridana) are marked with an ear tag (#1 monel fingerling tags) in each ear in addition to fur clipping to track movements of individuals among treatment units that are related to fire or to invasion of woody vegetation. Species, sex and reproductive condition of individual small mammals, trap station and any unusual features (e.g., the presence of ticks, fleas or bot fly larvae, variation in color pattern such as stars or blazes) are recorded at each capture of an individual in each trapping period. Body mass is recorded during the first capture of an individual on a trapline. Reproductive information recorded for males is the presence or absence of scrotal testes. Pregnancy is determined by palpation of the abdomen of females; no effort is made to assess the number of embryos. Presence or absence of conspicuous mammae also is recorded. Conspicuous mammae indicate that the female has been reproductively active and is nursing or has nursed offspring. Individuals are weighed to nearest 0.5 g for those weighing less than or equal to 50 g and nearest 1 g for those weighing greater than 50 g by using Pesola balances of an appropriate size.

Form of Data Output: The total number of mammals captured by species by trapline forms the database CSM05.

Summary of All Changes: We began trapping small mammals along the permanent traplines in December 1999 before the fire treatments were reversed. The treatment unit 001A (which was to become R20A) was burned annually from 1972 through 2000. In spring 2001, it became a long-term unburned site except for an accidental wildfire that occurred in spring 2008 after we had completed our small mammal surveys. The treatment unit 020A (which was to become R01A) was unburned except by wildfires in 1980 and 1991 before annual spring burning began in spring 2001. Note that the traplines on R20A are not the same as those used previously in 001A (CSM06).

At the beginning of the reversal of the fire regimes on these two treatment units, we intensively trapped small mammals. From December 1999 through December 2001, we used two methods of individually marking small mammals. On each small mammal, we both toe-clipped and applied an ear tag to the right ear of an individual (except for shrews). To uniquely identify an individual by toe clipping, we removed at most 1 digit per foot. Ear tags (each with a unique number) also were used, but ear tags are often lost, especially if only one ear is tagged and, subsequently, the history of that individual also is lost. These methods of marking allowed us to both identify individuals across traplines on the two treatment units and among trapping periods. Generally, both treatment units were trapped before the spring fire in March or April and then after the spring fire in May, June and then November-December from 2000 to 2002. We continued the general trapping plan in 2003, but used hair-clipping on different positions of the body to track small mammals among different trapping periods. After 2003, hair clipping was solely used as described above in the Methods and sampling occurred only in the spring and autumn of each year. Hair clipping allowed enumeration of the number of different individuals per species captured along each trapline, but not individual recognition. In spring 2008, we started ear-tagging deer mice, white-footed mice and eastern woodrats in addition to hair clipping to gain more information about how these different fire regimes are affecting movements of these three species given the change in vegetation since the beginning of the study.

Small mammals were not trapped on these traplines in autumn 2003 and spring 2009.

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