small mammals

CSM01 Seasonal Summary of Numbers of Small Mammals on 14 LTER Traplines in Prairie Habitats 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 two 4-day trapping periods in spring (late February to early April) and autumn (early October to mid-November) for each of 14 permanent traplines established on seven fire-grazing treatments (two traplines per treatment). These seven fire-grazing treatments include three sites that are grazed by bison (1 unburned, 1 annual burn and 1 4-year burn) and four sites that are not grazed by bison (1 unburned, 1 annual burn and 2 4-year burn).

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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 to determine the effects of weather patterns, occurrence of fire, frequency of fire, topographic features and bison grazing on populations and communities of small mammals.


Location of Sampling Stations: Ungrazed, unburned - 020B; Grazed, unburned - N20B; Ungrazed, annual burn - 001D; Grazed, annual burn - N01B; Ungrazed, 4 yr. burn - 004B, 004F; Grazed, 4 yr. burn - N04D

Frequency of Sampling: All sites are sampled in autumn (early October to mid-November) after most reproduction by small mammals has occurred and before winter stress is significant and in spring (late February to early April) before fire has occurred on those sites to be burned that year to estimate both early spring abundance and winter survival (difference in relative abundance between autumn and spring).

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 two permanent traplines in each of seven treatment units. trapline consists of 20 stations with an inter-station distance of 15 m and terminal stations (1 and 20) at least 50 m from the boundary of the treatment unit. When possible, each trapline was placed so that station 1 was in upland (shallow soil) and station 20 in lowland prairie (deeper soil), and so the two traplines within a treatment unit would include about 16 stations in upland, 8 stations across limestone outcrops and 16 stations in lowland. Because of the topographic goals, the two traplines within a treatment unit are not replicates of each other and the topographic goals were not always achieved. Stations 1, 5, 10, 15 and 20 on each trapline 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, deer licking traps or raccoons or crows setting off traps), traps are set for additional nights until < 50% of traps per night are closed without captures on that trapline. Small rocks are placed on traps in habitats that have little cover (e.g., on grazing lawns created by bison) to reduce problems due to wind. During the two trapping sessions each season, bison are removed from the phase II area of the bison enclosures to avoid damage to traps (e.g., stepping or rolling on them) and impacts on trap effectiveness (bison nuzzling or licking traps) and to ensure safety of field personnel.

All traps are checked early each morning, but after the end of the nocturnal activity period. Seven traplines are run simultaneously, one in each treatment, followed by the setting of the next series of traplines in the next week. The first trapline to be trapped in each treatment unit is selected at random by using a random number generator. The time of trapping in each season is selected by attempting to place the dark phase of the moon (no moon) in the middle of the two sampling periods.

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 as follows: on the right shoulder (first set of traplines in a spring sampling period), left shoulder (second set of traplines in a spring sampling period), right rump (first set of traplines in an autumn sampling period) and left rump (second set of traplines in an autumn sampling period). 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 < 50 g and nearest 1 g for those weighing > 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 CSM01.

Summary of All Changes: In autumn 1981, two traplines were established in each of ten experimental fire treatments (001D, 004B, 004D, 004F, 004G, 010A, 000B, N01D, N04D and N00D). Live-trap surveys were conducted in spring, summer and autumn; small mammals were marked by toe-clipping procedures. During winter 1981-1982, the Konza Prairie management committee shifted treatment boundaries to create watershed units for those treatment areas that drained into Kings Creek. Because of that decision, our traplines in N00D were encompassed in the new boundaries of N01D. Therefore, we established two new traplines in another treatment unit (N00B) in spring 1982. Also, the experimental designation for N01D was changed to N01B. During spring, summer and autumn 1982, surveys were conducted using 22 traplines; use of the two traplines in N00D was discontinued before the spring 1983 survey. Data for small mammals captured in N00D for spring, summer and autumn sampling periods in 1982 are found in CSM06.

From spring 1983 through summer 1984, censuses were conducted using two traplines in each of ten treatments (001D, 004B, 004D, 004F, 004G, 010A, 000B, N01B, N04D and N00B). In autumn 1984, four new traplines were established with two traplines in 002C and two in 002D (24 total sampling lines). Four more traplines were added in autumn 1985 with two in 010D and two in 001A (28 total sampling lines). After 1987, summer sampling was discontinued because of the intensive labor required to close traps in the morning and open traps in late afternoon each day on each trapline in each trapping period. All data for small mammals captured in summer trapping periods are found in CSM06. In 1988, Konza Prairie management committee changed unburned research treatments to treatments with a 20-year frequency of occurrence of fire and, therefore, 000B and N00B became 020B and N20B, respectively.

The treatment units (N01B and N04D) remained unburned from 1968 until spring 1988 when annual burning was initiated on N01B and the 4-year cycle was initiated on N04D. Spring fires occurred after our trapping session in these and other treatment units. N20B was not burned in 1988, but it had been burned in 1980.

Before the spring sampling period in 1989, the number of traplines sampled was reduced from 28 traplines to 14; the 14 traplines remaining included two traplines in each of seven experimental treatments (001D, 004B, 004F, 020B, N01B, N04D and N20B). Selection of these 14 traplines was based on the goal of maintaining the sampling of small mammals in annual, 4- year and 20-year burn treatments in both ungrazed prairie (001D, 004B and 020B, respectively) and in the same fire treatments in prairie grazed by bison (N01B, N04D and N20B). In addition, a second ungrazed 4-year fire treatment (004F) was continued to help monitor climatic effects on small mammals in prairie experiencing periodic fires. Data for small mammals captured on traplines that were discontinued (001A, 002C, 002D, 004D, 004G, 010A and 010D) can be found in CSM06.

In autumn 1990, we started clipping hair at the first capture of a small mammal in each season in exchange for the more invasive clipping of <= 1 digit per foot, which had been used since 1981 to identify individuals. Hair clipping allowed enumeration of the number of different individuals per species captured along each trapline, which was all that was required for maintenance of the CSM01 data set. In autumn 2008, we started ear-tagging deer mice, white- footed mice and eastern woodrats to gain more information about how new fire treatments near the 14 core traplines and how the invasion of woody vegetation was affecting movements of these three species.

In May 1992, gates were opened between phase I and phase II of the bison area. N01B, N04D and N20B lie within the phase II area. All sampling periods from autumn 1981 through spring 1992 on these three treatment units occurred on traplines that had not been grazed by bison.

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