surveys

Rabbit Population Densities at the Sevilleta National Wildlife Refuge, New Mexico (1992-2004)

Abstract: 

This study measured the population dynamics of black-tail jackrabbits (Lepus californicus) and desert cottontail rabbits (Sylvilagus auduboni) in the grasslands and creosote shrublands of McKenzie Flats, Sevilleta National Wildlife Refuge.  The study was begun in January, 1992, and continued quarterly each year.  Rabbits were sampled via night-time spotlight transect sampling along the roads of McKenzie Flats during winter, spring, summer, and fall of each year.  The entire road transect was 21.5 miles in length. Measurements of perpendicular distance of each rabbit from the center of the road were used to estimate densities (number of rabbits per square kilometer) via Program DISTANCE.  Results from 1992 to 2002 indicated that spring was the peak density period of the year, with generally steady declines through the year until the following spring. Evidence of a long-term "cycle" (e.g., the 11 year cycle reported for rabbits in the Great Basin Desert) did not appear in the Sevilleta rabbit populations.

Core Areas: 

Data set ID: 

113

Additional Project roles: 

304
305

Keywords: 

Purpose: 

The purpose of the study was to assess the dynamics of rabbit populations in the grasslands and creosote shrublands of the Sevilleta NWR.  Rabbits are important herbivores in these habitats, and can influence NPP and plant species composition.  In turn, these animals also provide high-quality prey for many of the Sevilleta's mammal and reptile carnivores and birds of prey.  Density data on rabbits can be used to calculate herbivore pressure on the plant communities.

Data sources: 

sev113_rabbitdens_20040226.txt

Methods: 

When the samples were collected: The samples were collected in winter, spring, summer, and fall, of each year.  Rabbit populations were sampled during a single night during each of these four seasons per year.  Dates of collection varied in some years, but generally the sampling was conducted in January, April, July, and October.

Sampling Design: The rabbits were sampled along 21.5 miles of roadway that was broken up into four "legs" of varying lengths.

Leg A:  Black Butte southward to Five Points (5.7 miles).

Leg B:  Five Points eastward to the turnoff before Palo Duro Canyon (4.1 miles).

Leg C:  Palo Duro turnoff northward to the old McKenzie Headquarters site (6.1 miles).

Leg D:  McKenzie Headquarters site northwestward to Black Butte (5.6 miles).

Measurement Techniques: The rabbit surveys were conducted at night using spotlights. Surveys began one hour after sunset, when no trace of sunlight or dusk remained.  Beginning in 1998, samples were taken only during full-moon periods. A pickup truck was driven slowly (8-10 miles per hour) along the road of the 21.5 mile circuit.  Two (or more) observers stood in the bed of the pickup truck, and scanned the left and right sides (respectively) of the road with spotlights, while the driver kept watch for rabbits directly in front in the road.  During 1992, the spotlights were Q-Beam 500,000 candlepower spotting lights, with both flood and spot settings (spot settings were used during the rabbit sampling).  From 1993 through 1996, Q-Beam spotlights with 1,000,000 candlepower were used.  In 1997, new spotlights with 3,000,000 candlepower were used; these lights were set permanently on "flood", but illuminated well at distances previously reached by the spot settings of the less-powerful spotlights.  

In addition to the spotlights used by the standing observers in the bed of the pickup truck, two spotlights mounted on the pillar posts of the truck's cab were turned on and set for the roadsides ahead of the truck; these lights, coupled with the high-beam setting of the truck's headlights, illuminated the road in front of the truck for approximately 100 meters. When a rabbit was observed, one person's spotlight illuminated the spot at which the rabbit was first seen.  The second person's spotlight would track the rabbit, so that it was not counted twice.  A meter tape was walked out from the center of the truck bed (which equalled the center of the road) in a perpendicular direction from the road to the location at which the rabbit was first observed.  That distance was measured and recorded to the nearest meter.

If a rabbit was observed in the middle of the road, the distance was recorded as zero.  Beginning in January, 2000, perpendicular distances to the rabbits were taken with a laser range finder, with accuracies of less than 1 meter (accuracies were tested before field use and confirmed to be <1m).  Generally, rabbits within 100 meters of the road could be seen relatively clearly with all three types of spotlights. Other data recorded included (1) the odometer reading in miles from the beginning of the sample at Black Butte (odometers were reset to zero at the start of the sample), (2) whether the rabbit was on the Left or Right side of the road, and (3) the species of rabbit.  In addition, incidental data were recorded on weather conditions, presence of clouds and moon, and the time at which the survey was begun, along with the times at which each Leg was begun and finished.  Finally, the names of the people on the sampling crew were recorded.

Analytical Procedures: The perpendicular distance data were entered into Program DISTANCE to estimate the total density of rabbits in the study area. Values were computed as numbers of individuals per square kilometer In the analyses, if there were sufficient numbers of rabbits (>10 per leg), the difference legs were analyzed separately, and the resulting mean densities were estimated by averaging the four leg estimates.  In the results tables below, these instances are indicated by the category, "MEAN".  If sample sizes were too small to estimate the four legs separately, then all the rabbit observations were pooled together, and a density estimate for the entire 21.5 mile survey was calculated. These results are indicated by the category, "ALL".

Quality Assurance: 

The program DISTANCE command codes were as follows:

Options;

Title='SEVILLETA RABBIT

DENSITIES';

Type=Line;


Length/Units='Miles';

Area/Units='Hectares';

Distance=Perp/Measure='Meters'/Exact;

Object=Single;

End;


Data;

Stratum/label='DATE ENTERED HERE';

Sample=1/Label='ALL

LEGS, DATE ENTERED HERE'/Effort=21.5;

DISTANCE DATA ENTERED HERE, SEPARATED BY COMMAS;

End;


Estimate;

Est /key=uniform /adj=cosine  /select=sequential /criterion=AIC /monotone=weak;

Est /key=uniform /adj=hermite /select=sequential /criterion=AIC /monotone=weak;

Est /key=hnormal /adj=cosine  /select=sequential /criterion=AIC /monotone=weak;

Est /key=hnormal /adj=hermite /select=sequential /criterion=AIC /monotone=weak;

Pick=AIC;

Density by sample;


End;

Response of Larrea tridentata to a Natural Extreme Cold Event at the Sevilleta National Wildlife Refuge, New Mexico

Abstract: 

Shrub expansion into grasslands can cause abrupt changes in ecosystem processes. Creosote (Larrea tridentata) is a native shrub in warm, arid deserts of the southwestern US and has taken over C4 grasslands. A limited freeze tolerance is thought to dictate the northern boundary of creosote and the Sevilleta National Wildlife Refuge occurs near to the northern extent of creosote. Cold temperatures are known to damage creosote. In laboratory trials, temperatures of -25 for 1 hour lead to xylem damaging embolism in nearly 100% of stems and temperatures of -24 C lead to seedling death in the lab. Sevilleta LTER meteorological data from a station located within creosote shrublands indicated a low temperature of -20 C between 1999 and 2010. On February 3, 2011 temperatures hit record lows in central New Mexico, reaching -30 C at shrublands within the SNWR. To address how creosote responds to a natural extreme cold events, plots were established to monitor creosote initial response and regrowth following the cold event. Initial surveys will determine canopy death and subsequent surveys of the same individuals will allow us to determine how creosote responds to record cold temperatures.

Core Areas: 

Additional Project roles: 

45

Data set ID: 

244

Keywords: 

Methods: 

Plots were established at 6 locations across SNWR. Criteria for site selection included the presence of L. tridentata, flat terrain to limit microtopographic impacts, close proximity to existing meteorological stations, and variation in shrub density between sites. At each site, approximately 200 shrubs were evaluated within circular plots (20m in diameter) with the number of plots at each site varying in shrub density. Initial surveys to determine canopy death were conducted in early April 2011. These surveys consisted of tagging each shrub with an unique ID, estimating canopy death, and measuring maximum canopy height, maximum width and the perpendicular width to max width.

Additional information: 

Study Area 1:  

Study Area Name:  South Gate

Study Area Location: Located across the road from the met station located at South Gate.

Bounding Box:  

North Coordinate:  34.42

South Coordinate: 34.19

East Coordinate: -106.513

West Coordinate: -107.08

Study Area 2:  

Study Area Name: Microwave shrubland

Study Area Location: Located near the Microwave tower on the West side of the SNWR. Plots are located 100 to 200 m down the road just East of the tower towards Red Tank. Plots are on the West side of the road.

Bounding Box:  

North Coordinate: 34.42

South Coordinate: 34.19

East Coordinate: -106.518

West Coordinate: -107.08

Study Area 3:  

Study Area Name: BurnX shrubland site

Study Area Location: Located near Met station 52b, established near the burn enclosure (BurnX) Black Grama site.

Bounding Box:  

North Coordinate:  34.42

South Coordinate: 34.19

East Coordinate: -106.513

West Coordinate: -107.08

Gunnison’s Prairie Dog Use of Resource Pulses in a Chihuahuan Desert Grassland at the Sevilleta National Wildlife Refuge, New Mexico: Re-sight Scan Data

Abstract: 

Seasonal environments experience cyclical or unpredictable pulses in plant growth that provide important resources for animal populations, and may affect the diversity and persistence of animal communities that utilize these resources. The timing of breeding cycles and other biological activities must be compatible with the availability of critical resources for animal species to exploit these resource pulses; failure to match animal needs with available energy can cause population declines. Adult Gunnison’s prairie dogs emerge from hibernation and breed in early spring, when plant growth is linked to cool-season precipitation and is primarily represented by the more nutritious and digestible plants that utilize the C3 photosynthetic pathway. In contrast, summer rainfall stimulates growth of less nutritious plants using the C4 photosynthetic pathway. Prairie dogs should therefore produce young during times of increased productivity from C3 plants, while pre-hibernation accumulation of body fat should rely more heavily upon C4 plants.  If seasonal availability of high-quality food sources is important to Gunnison’s prairie dog population growth, projected changes in climate that alter the intensity or timing of these resource pulses could result in loss or decline of prairie dog populations.  This project will test the hypothesis that population characteristics of Gunnison's prairie dog, an imperiled grassland herbivore, are associated with climate-based influences on pulses of plant growth.

Data set ID: 

242

Core Areas: 

Additional Project roles: 

40
41

Keywords: 

Methods: 

Gunnison’s prairie dogs will be monitored at 6 colonies, with 3 colonies each occurring with the range of prairie and montane populations. Colonies for study within the prairie populations occur at Sevilleta National Wildlife Refuge (n = 3 prairie populations) and at Vermejo Park Ranch (n = 3 montane populations).  Live-trapping of prairie dogs will be conducted during 3 periods of the active seasons—following emergence (April), after juveniles have risen to the surface (mid-to-late June), and pre-immergence (beginning in August).  Trapping will occur for 3-day periods, following pre-baiting with open traps.  At capture, sex and body mass of each individual will be recorded.  Blood and subcutaneous body fat samples will be collected nondestructively for analysis of isotopic composition.  Prairie dogs will be marked with dye, and released on site immediately following processing.  After trapping periods at each site have concluded, population counts will be conducted during 2-3 re-sighting (or recapture) periods for each prairie dog colony.  Resighting observation periods will be ~3 hours in length, and consist of 2-6 systematic scans of the entire colony, beginning and ending from marked points outside of the colony boundary.  During each observation period, prairie dogs will be counted, recorded as marked or unmarked, and location on the colony noted.  

Vegetation cover and composition measurements will be collected (or obtained at Sevilleta, where such data is already being collected) during pre- and post-monsoon periods of the active season.  Total cover will be measured by plant species (or to genus if species is indeterminable). Total cover will be measured at 12 grid points per colony using Daubenmire frames (0.5 m x 0.5 m), and at 12 grid locations 200-800 m outside of each colony boundary.  Adjacent to each Daubenmire frame, a 20 cm x 30 cm sample of vegetation will be clipped and dried for determination of volumetric moisture content of vegetation.  

Primary productivity variables (cover, moisture content) will be tested for correlations to individual and population-level condition indicators in prairie dogs.  Carbon isotope ratios (δ13C) from prairie dog blood and fat samples will be analyzed on a continuous flow isotope ratio mass spectrometer.  The relative contribution of C3 and C4 plants to the diet of each individual will be determined based upon δ13C ratios for C3 and C4 plants in the study area and a 2-endpiont mixing model, and will be calculated for each individual animal, population and season.  Population estimates will be calculated using mark-resight estimates, and compared to maximum above-ground counts.  The influence of resource pulses on prairie dog population parameters will be tested by comparing the vegetation cover, moisture content, and ratio of total C3:C4 plant cover to the ratio of C3:C4 plants in prairie dog diets, population estimates, and juvenile:adult ratios as an index to population recruitment.   

Instrumentation: 

*Instrument Name: Continuous flow isotope ratio mass spectrometer

*Manufacturer: Thermo-Finnigan IRMS  Delta Plus 

*Instrument Name: Elemental Analyzer

*Manufacturer: Costech

*Model Number: ECS4010

Additional information: 

Other Field Crew Members: Talbot, William; Duran, Ricardo; Gilbert, Eliza; Donovan, Michael; Nichols, Erv; Sevilleta LTER prairie dog field crew led by Koontz, Terri; Sevilleta NWR prairie dog field crew led by Erz, Jon.

Tissue samples are analyzed for stable carbon isotope ratios in stable isotope laboratory operated by Dr. Zachary Sharp and Dr. Nicu-Viorel Atudorei of the Department of Earth and Planetary Sciences, University of New Mexico.

Plant phenology or life-history pattern changes seasonally as plants grow, mature, flower, and produce fruit and seeds. Plant phenology follows seasonal patterns, yet annual variation may occur due to annual differences in the timing of rainfall and ambient temperature shifts. Foliage growth and fruit and seed production are important aspects of plant population dynamics and food resource availability for animals.

The late Dr. Clifford S. Crawford established the Sevilleta’s Schoolyard LTER Program which funds an educational outreach program known locally as the Bosque Ecosystem Monitoring Program (BEMP).  The major focus of the program is to monitor key indicators of structural and functional change in the Middle Rio Grande riparian cottonwood forest ('bosque') corridor through central New Mexico, including the Sevilleta National Wildlife Refuge.

Gunnison's Prairie Dog Use of Resource Pulses in a Chihuahuan Desert Grassland at the Sevilleta National Wildlife Refuge, New Mexico: Capture Data

Abstract: 

Seasonal environments experience cyclical or unpredictable pulses in plant growth that provide important resources for animal populations, and may affect the diversity and persistence of animal communities that utilize these resources. The timing of breeding cycles and other biological activities must be compatible with the availability of critical resources for animal species to exploit these resource pulses; failure to match animal needs with available energy can cause population declines. Adult Gunnison’s prairie dogs emerge from hibernation and breed in early spring, when plant growth is linked to cool-season precipitation and is primarily represented by the more nutritious and digestible plants that utilize the C3 photosynthetic pathway. In contrast, summer rainfall stimulates growth of less nutritious plants using the C4 photosynthetic pathway. Prairie dogs should therefore produce young during times of increased productivity from C3 plants, while pre-hibernation accumulation of body fat should rely more heavily upon C4 plants. If seasonal availability of high-quality food sources is important to Gunnison’s prairie dog population growth, projected changes in climate that alter the intensity or timing of these resource pulses could result in loss or decline of prairie dog populations. This project will test the hypothesis that population characteristics of Gunnison's prairie dog, an imperiled grassland herbivore, are associated with climate-based influences on pulses of plant growth.

Data set ID: 

241

Core Areas: 

Additional Project roles: 

37
38
39

Keywords: 

Methods: 

Gunnison’s prairie dogs will be monitored at 6 colonies, with 3 colonies each occurring with the range of prairie and montane populations. Colonies for study within the prairie populations occur at Sevilleta National Wildlife Refuge (n = 3 prairie populations) and at Vermejo Park Ranch (n = 3 montane populations). Live-trapping of prairie dogs will be conducted during 3 periods of the active seasons—following emergence (April), after juveniles have risen to the surface (mid-to-late June), and pre-immergence (beginning in August). Trapping will occur for 3-day periods, following pre-baiting with open traps. At capture, sex and body mass of each individual will be recorded. Blood and subcutaneous body fat samples will be collected nondestructively for analysis of isotopic composition. Prairie dogs will be marked with dye, and released on site immediately following processing. After trapping periods at each site have concluded, population counts will be conducted during 2-3 re-sighting (or recapture) periods for each prairie dog colony. Resighting observation periods will be ~3 hours in length, and consist of 2-6 systematic scans of the entire colony, beginning and ending from marked points outside of the colony boundary. During each observation period, prairie dogs will be counted, recorded as marked or unmarked, and location on the colony noted. Vegetation cover and composition measurements will be collected (or obtained at Sevilleta, where such data is already being collected) during pre- and post-monsoon periods of the active season. Total cover will be measured by plant species (or to genus if species is indeterminable). Total cover will be measured at 12 grid points per colony using Daubenmire frames (0.5 m x 0.5 m), and at 12 grid locations 200-800 m outside of each colony boundary. Adjacent to each Daubenmire frame, a 20 cm x 30 cm sample of vegetation will be clipped and dried for determination of volumetric moisture content of vegetation. Primary productivity variables (cover, moisture content) will be tested for correlations to individual and population-level condition indicators in prairie dogs. Carbon isotope ratios (δ13C) from prairie dog blood and fat samples will be analyzed on a continuous flow isotope ratio mass spectrometer. The relative contribution of C3 and C4 plants to the diet of each individual will be determined based upon δ13C ratios for C3 and C4 plants in the study area and a 2-endpiont mixing model, and will be calculated for each individual animal, population and season. Population estimates will be calculated using mark-resight estimates, and compared to maximum above-ground counts. The influence of resource pulses on prairie dog population parameters will be tested by comparing the vegetation cover, moisture content, and ratio of total C3:C4 plant cover to the ratio of C3:C4 plants in prairie dog diets, population estimates, and juvenile:adult ratios as an index to population recruitment.

Instrumentation: 

Instrument Name: Continuous flow isotope ratio mass spectrometer Manufacturer: Thermo-Finnigan IRMS Delta Plus Model Number: Instrument Name: Elemental Analyzer Manufacturer: Costech Model Number: ECS4010

Additional information: 

Field Crew: Hayes, Chuck; Talbot, William; Duran, Ricardo; Gilbert, Eliza; Donovan, Michael; Nichols, Erv; Sevilleta LTER prairie dog field crew led by Koontz, Terri; Sevilleta NWR prairie dog field crew led by Erz, Jon.

Coyote Scat Surveys in Chihuahuan Desert Grassland and Shrubland Sites, Spring, Summer and Fall at the Sevilleta National Wildlife Refuge, New Mexico (2008-2009)

Abstract: 

This data set contains information regarding carnivore scat surveys that were performed at sites in grama grassland and both creosote and mesquite shrubland habitats at the Sevilleta NWR. A total of nine surveys were carried out along road-based transects, each of which is a mile long, during one season in 2008 (June-July) and three seasons in 2009: spring (April-May), summer (July-August), and fall (October-November). There were 10 transects in grassland areas and 10 in shrubland areas in 2008. All 20 transects, as well as two additional transects in grassland areas, were surveyed in 2009. For more information on the structure of the vegetation surrounding these road based transects, see the "Vegetation surveys in grassland and shrubland sites that are associated with coyote scat surveys at the Sevilleta NWR, 2008-2009" data set. Scat samples were identified in the field and collected for genetic and stable carbon isotope analysis. Field recorded variables include: scat freshness, maximum diameter, length, and GPS coordinates, as well as the field-based species identification for the sample. Information on the lab based species and individual identification results are also presented.

This data was collected in order to obtain information on the size and feeding ecology of the coyote populations in grassland vs. shrubland habitats in three seasons (spring, summer and fall) and two years (2008 and 2009) at the Sevilleta NWR. A mark recapture analysis can be performed on the data from 2009 since two surveys were carried out for each scat transect in each of the three seasons and coyote scats were run through a genetic analysis to determine individual identity of the coyotes. A rough assessment of coyote habitat use can also be performed using the individual identity and coyote scat location information. Future isotope analysis will indicate whether the base of the food chain is C4 (grass) vs. C3 (shrubs) plants in grassland vs. shrubland habitats in each of the three seasons (spring (pre-monsoon), summer (monsoon) and fall (post monsoon)) and in each of two years (2008 and 2009).

Data set ID: 

220

Core Areas: 

Additional Project roles: 

373
374
375

Keywords: 

Data sources: 

sev220_coyotescatsurvey_20150618.csv

Methods: 

Experimental Design: Carnivore scat surveys were carried out along roads located in grassland and shrubland habitats throughout the Sevilleta NWR. Surveys were done along 20 road based transects in 2008 and 22 transects in 2009. 10 transects were located in grassland areas and 10 in shrubland areas in 2008; there were 12 transects in grassland areas and 10 in shrubland areas in 2009.

Instrumentation: 

Sampling Design: Each scat transect was 1 mile long and was separated from all other transects by at least 1 mile to ensure independence of scat samples collected on different transects. Each transect surveyed in 2008 (n=20) was surveyed a total of three times between June 24th and July 24th, 2008. Each transect surveyed in 2009 (n=22) was surveyed a total of six times between April 13th and November 6th, 2009. For 2009, two surveys were carried out in each of three seasons: spring (April-May 2009); summer (July-August 2009); and fall (October-November 2009).

Field methods: The beginning and end points of each scat transect were marked at the beginning of the summer field season in 2008, and then re-marked as necessary at the beginning of the spring field season 2009, with a wooden stake and a pin flag so that each of the three surveys in 2008 and six surveys in 2009 were carried out along the same road segments. The end points of three transects (D,E, and R) were moved slightly from their original locations in summer, 2008 and two transects were added (U and V) in 2009. The coordinates of all of these new locations were determined via GPS and recorded. Before the first scat survey in 2008, and before the first scat survey in each season in 2009, all transects were cleared of all visible carnivore scat. During each of the three subsequent surveys in 2008, and during the two subsequent surveys in each season in 2009, each complete carnivore scat sample encountered was measured and collected. A sample was considered to be incomplete if it were clearly torn or very small and likely missing part of the sample. When clearing transects and conducting surveys, the transects were driven in a field vehicle (truck) at 5-10mph and the driver looked through both the windshield and front windows for scat samples. In 2008, there was a second observer who would sit in the passenger seat and look through the windshield and front windows. When a particular item could not be identified from within the truck, the observer would get out of the vehicle and investigate the item further. When a carnivore scat sample was encountered, a photograph was taken and the GPS coordinates for the location of the scat were recorded. If the scat was composed of multiple pieces that were spread out along the road, then an attempt was made to record the GPS coordinates of a point midway between the two pieces that were furthest apart. If the scat was not flattened or otherwise degraded, two measurements of maximum diameter and one measurement of length were recorded. When a scat contained multiple pieces, these measurements were generally taken on the longest piece. If part of the scat was flattened, then measurements were taken on the longest, unflattened piece. Maximum diameter was measured using calipers and length was measured using a clear, plastic ruler. Once the measurements were taken, small pieces of the scat were removed using flame sterilized tweezers and placed in a 2mL plastic tube containing DET buffer. The buffer preserved the samples for future genetic analysis. The remainder of the sample was then collected in a ziplock bag for future drying and carbon isotope analysis.

Laboratory Procedures: 

All scat samples were dried for 24 hours at 70 degrees Celsius and, in future, will be prepared and run through a stable carbon isotope analysis in a coupled element analyzer and mass spectrometer. Small subsamples of each scat will be run through a mitochondrial DNA species test. All samples identified as coyotes in this test will then be run through a microsatellite analysis, with 8 loci, to identify individuals.

Quality Assurance: 

Data were recorded in the field and entered into a spreadsheet in Excel. Field recorded comments were removed since they did not add significantly to the value of the data and, in some cases, their importance or meaning would have been difficult to explain. No automated or quantitative data quality checks were performed.

Additional information: 

Additional Information on the personnel associated with the Data Collection / Data Processing Other field crew members:Jon Erz and Teresa Seamster

Small Mammal Exclosure Study (SMES) Ant Data from Chihuahuan Desert Grassland and Shrubland at the Sevilleta National Wildlife Refuge, New Mexico (1995-2005)

Abstract: 

Animal consumers have important roles in ecosystems, determining plant species composition and structure, regulating rates of plant production and nutrients, and altering soil structure and chemistry. This is data for numbers and species of seed harvester ant nests mapped from each of the SMES study plots. Seed harvester ant nests were mapped on each of the study plots once each year in the autumn. Ant nest maps were drawn on to pre-designed plot diagrams. Each nest was located on the diagram in reference to one of the 36 vegetation quadrat marker posts. The distance from the post, direction from the post, and species name were plotted on the map diagram. Data such as total numbers of nests of each ant species, and spatial arrangement of nests, were then taken from the diagram maps. The following question was asked: Do small mammals interact with other herbivore and granivore consumers enough to affect the species composition and abundances of other consumers such as ants?

Core Areas: 

Data set ID: 

88

Additional Project roles: 

188
189

Keywords: 

Data sources: 

sev088_smesant_04102009.txt

Methods: 

Experimental Design: 

The Small Mammal Exclosure Study plots are located in a grassland and shrubland. These plots were established in 1995 to monitor the effects of indigenous small mammals on plant communities across the Chihuahuan Desert grassland and shrubland. There are four blocks distributed randomly at each site; each block contains three treatments plots: unfenced control (C), fenced with poultry wire to exclude lagomorphs (L), and fenced with hardware cloth and poultry wire to exclude rodents and lagomorphs (R).  The three treatment plots in each block are separated by 20 meters and were randomly assigned to one of the four plots for each block.  Each plot (36m x 36 m) contains 36 permanent 1 m2 subplots.  Vegetation measurements have been consistently taken on these subplots since 1995 and  in 1996 fenced exclosures were installed.

Data Collection Methods: 

Ant nests were mapped from each of the study plots once each year, in the autumn. An observer walks east to west and west to east along each of the 6 lines of rebar markers looking for ant nests. The observer locates each ant nest on a diagram of the study plot using rebar markers as reference points. The position of the nest relative to the nearest rebar was marked on the diagram as a small circle. The species of ant was noted as a 2-letter acronym, first letter of the genus, and first letter of the species, within the circle on the paper. The distance from the rebar was noted in meters, and the direction from the rebar was indicated on the diagram by a line drawn between the rebar and the nest. Ant species mapped include: all Pogonomyrmex species, Aphenogaster cockerelli, and Myrmecocystus species (non-seed harvesters). Pheidole species were not mapped.

Maintenance: 

Metadata entered into access. 7 April 2009 tlk

Quality Assurance: 

Contact David Lightfoot for QA/QC procedures. dlightfo@unm.edu

Additional information: 

Rabbit Population Dynamics in Chihuahuan Desert Grasslands and Shrublands at the Sevilleta National Wildlife Refuge, New Mexico (1992-present)

Abstract: 

This study explores the population dynamics of black-tail jackrabbits (Lepus californicus) and desert cottontail rabbits (Sylvilagus auduboni) in the grasslands and creosote shrublands of McKenzie Flats, Sevilleta National Wildlife Refuge. The study was initiated in January 1992, and continues quarterly each year. Rabbits are sampled via night-time spotlight transect sampling along the roads of McKenzie Flats once during winter, spring, summer, and fall. The route is 21.5 miles long. Measurements of perpendicular distance of each rabbit from the center of the road are used to estimate densities (number of rabbits per square kilometer) via Program DISTANCE. Results from January 1992 to May 2004 indicated that spring was the period of peak density period, with generally steady declines through the rest of the year until the following spring. Evidence of a long-term "cycle" (e.g., the 11-year-cycle reported for rabbits in the Great Basin Desert) does not appear in the Sevilleta rabbit populations.

Core Areas: 

Data set ID: 

23

Additional Project roles: 

280
281
282
283
284

Keywords: 

Purpose: 

The purpose of the study is to assess the dynamics of rabbit populations in the grasslands and creosote shrublands of the Sevilleta NWR. Rabbits are important herbivores in these habitats, and can influence net primary productivity and plant species composition. In turn, these animals also provide high-quality prey for many of the Sevilleta NWR's carnivores and birds of prey. Density data on rabbits can also be used to calculate herbivore pressure on the plant communities.

Data sources: 

sev023_rabbitpopns_20150310.txt

Methods: 

Sampling Design:

The rabbits are sampled along 21.5 miles of roadway that is broken up into four "legs" of varying lengths.

Leg A:Black Butte southward to Five Points (5.7 miles).

Leg B:Five Points eastward to the turnoff before Palo Duro Canyon (4.1 miles).

Leg C: Palo Duro turnoff northward to the old McKenzie Headquarters site (6.1 miles).

Leg D: McKenzie Headquarters site northwestward to Black Butte (5.6 miles).

Sample Unit:

Individual rabbit.

Frequency of Sampling:

Sampled one night per season, four seasons per year.

Technique Citations:

Buckland, S. T., D. R. Anderson, K. P. Burnham, and J. L. Laake.1993. Distance Sampling. Estimating abundance of biological populations. Chapman and Hall, New York.  446 pp.

Measurement Techniques: 

The rabbit surveys are conducted at night using spotlights positioned out each side of a pick-up truck. Surveys began one hour after sunset, when no trace of sunlight or dusk remained. Beginning in 1998, all surveys are conducted on or near the full moon.  

The truck is driven slowly (8-10 miles per hour) along the 21.5 mile circuit. Two (or more) observers stand in the bed and scan the left and right sides (respectively) of the road with spotlights, while the driver keeps watch for rabbits directly in front of the vehicle.  

During 1992, the spotlights were Q-Beam 500,000 candlepower spotting lights, with both flood and spot settings (spot settings were used during the rabbit sampling).  From 1993 through 1996, Q-Beam spotlights with 1,000,000 candlepower were used.  In 1997, new spotlights with 3,000,000 candlepower were used; these lights were set permanently on "flood", but illuminated distances previously reached by the spot settings of the less-powerful spotlights. SInce 2002, 2,000,000,000 candlepower spotlight gave been used.

In addition to the spotlights used by the standing observers in the bed of the pickup truck, two spotlights mounted on the pillar posts of the truck's cab are turned on and set for the roadsides ahead of the truck; these lights, coupled with the high-beam setting of the truck's headlights, illuminate the road in front of the truck for approximately 100 meters. When a rabbit is observed, one person's spotlight illuminates the spot at which the rabbit was first seen.  The second person's spotlight tracks the rabbit so it is not counted twice.  A meter tape is walked out from the center of the truck bed (i.e., the center of the road) perpendicular to the location at which the rabbit was first observed.  That distance is measured and recorded to the nearest meter. If a rabbit is observed in the middle of the road, the distance is recorded as zero.  

Beginning in Jan. 2000, perpendicular distances are measured using a laser range finder, with an accuracy of 1 meter. Accuracy level is checked prior to sampling. Generally, rabbits within 100 meters of the road can be seen relatively clearly with all three types of spotlights.

Other data recorded includes (1) the odometer reading in miles from the beginning of the sample at Black Butte (odometers are reset to zero at the start of the sample), (2) whether the rabbit was on the left or right side of the road, and (3) the species of rabbit.  Incidental data on weather conditions is also noted including presence of clouds and moon, time at which the survey was begun, and times at which each leg was begun and finished. The names of the people on the sampling crew are also recorded. 

Analytical Procedures:  

Perpendicular distance data are entered into Program DISTANCE to estimate the total density of rabbits in the study area. Values are computed as numbers of individuals per square kilometer.

Instrumentation: 

2,000,000,000 candlepower Q-Beam spotlights.

Maintenance: 

File created 23 Nov. 1992 - SM

1-30-95: 1-23-95 data entered by Rosemary Vigil.9-11-97: doc file created by Robert R. Parmenter 9-11-97: 4-25-95 through 8-4-97 data entered by Robert R. Parmenter 9-19-97: archived by Gregg MacKeigan as rabbit_survey_92-97.dbf. 10-29-97: data for 10-27-97 entered and checked by Robert R. Parmenter 2-6-00: data for 1998, 1999, and Jan. 2000 entered and checked by Robert R. Parmenter. 12-25-00: data for April, July, and October 2000 entered and checked by Robert R. Parmenter. 2-6-01: data for February 2001 entered and checked by Robert R. Parmenter. 2-5-02: data for April, July and October 2001, and January 2002, entered and checked by Robert R. Parmenter. 6-26-02: data for April, 2002, entered and checked by Robert R. Parmenter. 7-24-02: data for July, 2002, entered and checked by Robert R. Parmenter. 10-25-02: data for October, 2002, entered and checked by Robert R. Parmenter. 12-30-05: data for 2003 and 2004 entered and checked, and final edits to metadata file made by Robert R. Parmenter. doc

Additional information: 

Dates of collection vary in some years, but sampling is generally conducted in January, April, July, and October.

Pino Gate Prairie Dog Study at the Sevilleta National Wildlife Refuge, New Mexico: Mound-Scale Lizard Data (2000-2002)

Abstract: 

Keystone species have large impacts on community and ecosystem properties, and create important ecological interactions with other species. Prairie dogs (Cynomys spp.) and banner-tailed kangaroo rats (Dipodomys spectabilis) are considered keystone species of grassland ecosystems, and create a mosaic of unique habitats on the landscape. These habitats are known to attract a number of animal species, but little is known about how they affect lizard communities. Our research evaluated the keystone roles of prairie dogs and kangaroo rats on lizards at the Sevilleta National Wildlife Refuge in central New Mexico, USA. We evaluated the impacts of these rodents on lizard communities in areas where prairie dogs and kangaroo rats co-occurred compared to areas where each rodent species occurred alone. Our results demonstrate that prairie dogs and kangaroo rats have keystone-level impacts on these lizard communities. Their burrow systems provided important habitats for multiple lizard species, especially the lesser earless lizard (Holbrookia maculata). At the landscape-scale, the total number of lizards was two-times greater on the where both prairie dogs and banner-tailed kangaroo rats co-occurred than where only kangaroo rats occurred.

Data set ID: 

177

Core Areas: 

Keywords: 

Data sources: 

sev177_pdoglizardmound_01312006.txt

Methods: 

Experimental Design

Mound-scale plots: To evaluate lizards associated with mound disturbance patches and rodent burrow systems, we established replicate mound-scale plots with paired "non-mound" control plots. The mound and non-mound plots were spatially intermixed within each landscape-scale plot. Lizards were sampled around 10 kangaroo rat mounds on the Krat plot, 10 prairie dog and 10 kangaroo rat mounds on the Pdog+Krat plot, and on paired non-mounds located 10 m away from sample mounds, in areas with minimal rodent disturbance.

Sampling Design

Lizards were visually sampled along strip transect lines established through each mound-scale plot. Strip transects on the mound-scale plots measured 1 m x 5 m.

Field Method

Lizards were sampled by walking slowly along each transect. Individuals were counted and identified to species. Lizards were sampled thoughout the spring and summer from spring 2000 through spring 2002.

Additional information: 

Additional Information on the personnel associated with the Data Collection / Data Processing

Field Crew Member: Julie McIntyre

Additional Study Area Information

Study Area Name: Pino Gate

Study Area Location: The study site was located near the base of the Los Pinos mountains and directly adjacent to the nothern fencline of the SNWR at Pino Gate

Elevation: 1600 m

Vegetation: Burrograss (Scleropogon brevifolius), sand dropseed (Sporobolus ryptandrus), and black grama (Bouteloua eriopoda) were the dominant vegetation.

Soils: Deep clayey loam soils

Geology: On an upper bajada slope, in a broad swale

Climate: Long-term mean annual precipitation is 243 mm, about 60% of which occurs during the summer. Long-term mean monthly temperatures for January and July are 1.5°C and 25.1°C, respectively.

Site history: Historically, prairie dogs were common throughout the area, but were exterminated by the early 1970’s (John Ford, United States Department of Agriculture Wildlife Services, personal  communication). Gunnison’s prairie dogs began to re-colonize the study site from adjacent private land in 1998. During our study, the colony occurred within a 5 ha area, near the base of the Los  Piños Mountains in an area with deep clayey loam soils. The site has been long inhabited by kangaroo rats, and represents typical northern Chihuahuan Desert grassland.

North Coordinate:34.406954
South Coordinate:34.406954
East Coordinate:106.606269
West Coordinate:106.606269

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