roads

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;

Coyote Scat Survey in the Chihuahuan Desert Grasslands and Creosote Shrublands at the Sevilleta National Wildlife Refuge, New Mexico (1992-2004)

Abstract: 

This study measured the population dynamics of coyotes 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.  Coyotes were sampled via scat counts 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. Scat counts over a week period (number of scats/mile/day) in each season along the roads were used to calculate the densities of coyotes (number of coyotes per square kilometer). Results from 1992 to 2002 indicated that autumn was the peak density period of the year, with generally steady declines through the year until the following autumn. Coyote populations appeared to fluctuate seasonally, but remained relatively stable at 0.27 +/- 0.03 (SE) coyotes per km2 during summer periods (this likely represents the "breeding pair" density, during which coyote pairs have set up territories and are raising young, but the pups have not as yet joined the parents in foraging activities).

Core Areas: 

Data set ID: 

49

Additional Project roles: 

82
83
84

Keywords: 

Purpose: 

The purpose of the study was to assess the dynamics of coyote populations in the grasslands and creosote shrublands of the Sevilleta NWR. Coyotes are important predators and omnivores in these habitats, feeding on a wide variety of vertebrates, arthropods, and plants. Populations of prey species may be controlled to some extent by coyote predation, in which case coyotes may have significant influences on the biodiversity and species composition of the desert grassland ecosystem.

Methods: 

Sampling Design:  

The scats 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).

Sample Unit:  

Each scat was the unit of sample.

Frequency of Sampling:  

Sampled one week per season, four seasons per year.

Sample Size:  

Variable, depending on scat abundance.

Technique Citations:  

Knowlton, Frederick F. 1984.  Feasibility of Assessing Coyote Abundance on Small Areas.  Unpublished Report, 14 pp.

Measurement Techniques: 

The number of scats deposited by coyotes per mile of roadway per day in a typical western basin-and-range landscape has been shown to be correlated with the absolute density of coyotes. Therefore, the objective was to measure the deposition rate of coyote scats on the roads of McKenzie Flats.

The process involved two samplings along the roads.  The first sampling involved the "clearing" of scats from the 21.5 mile survey route, so as to initialize the roadway with zero scats.  On the assigned day, the technician would drive an ATV slowly (less than 5 miles per hour) along the route.  When a coyote scat was observed, the technician would stop and pick up the scat, placing it into a zip-lock plastic bag that was labeled with the date and the "leg" letter.  Each "leg" was bagged separately.  The odometer reading of the scat location was recorded on the data sheet.  If more than one scat was observed at the same place, the number of scats was recorded as well. For health and safety, the technician wore gloves during this process, or used tongs or a small trowell to pick up the scats and place them into the bag.  When using the ATV, the technician wore a safety helmet.

During the early sampling periods (1992 to 1993), prior to the acquisition of the ATV in 1994, scats were collected by two technicians in a pick-up truck. One technician would drive, and the other would ride on the engine hood above the bumper, and scan the road as the truck was driven slowly along the road.  When a scat was observed, the driver would stop the truck while the rider would collect the scat.  The same data were recorded as described above.

One week following the "road clearing" survey, a second collection took place.  The scats were sampled in the same fashion as before, but each scat was placed individually in a labelled small zip-lock plastic bag.  Again, odometer readings were taken at the point of collection.  Multiple scats from the same location were placed in separate plastic bags.

The scats were then returned to the field station, and placed in freezers for preservation pending analysis of dietary items.

Analytical Procedures: 

Density values were computed as numbers of individuals per square kilometer.  According to F. Knowlton (see reference above), the relationship between absolute densities of coyotes (x-value, independent variable) and the number of scats per night per mile x 100 (y-value, dependent variable) is:

    Y = 2.66 + 11.42X, r2 = 0.97, n = 8

Transforming this equation for computing densities of coyotes from numbers of scats for each "leg" of the survey, and converting these values to numbers of coyotes per square kilometer, the coyote density equations for each survey "leg" are as follows:

     D = Density of coyotes/km2,  N = Total Number of Scats Collected/Leg

                                       after a 7-day period.

    Leg A (5.7 miles):   D = [0.2195(N) - 0.2329]/2.59

    Leg B (4.1 miles):   D = [0.3052(N) - 0.2329]/2.59

    Leg C (6.1 miles):   D = [0.2052(N) - 0.2329]/2.59

    Leg D (5.6 miles):   D = [0.2235(N) - 0.2329]/2.59

Data sources: 

sev049_coyotescat_20160302.csv

Additional information: 

The samples (scats) were collected in winter, spring, summer, and fall, of each year.  Scats were collected from the road once at the beginning of a collection period, and once at the end (usually, one week later) during each of these four seasons per year. Months of collection varied in some years, but generally the sampling was conducted in January, April, July, and October. The study began in January, 1992, and is continuing.

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

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

Abstract: 

This data set contains information regarding vegetation structure at sites in grama grassland and both creosote and mesquite shrubland habitats at the Sevilleta NWR. This information was collected at randomly selected sites throughout the refuge. Each site is within 100 meters of one of the 22 road-based transects(20 in 2008) that were used to carry out coyote scat surveys during three seasons (spring, summer and fall) in 2009 (see "Coyote scat surveys in grassland and shrubland sites at the Sevilleta NWR, spring, summer and fall 2009" data set). Data was collected within at total of 22 circular vegetation plots (40 in 2008), each of which is 30m in diameter. Each plot was surveyed a total of three times, specifically in: April (spring), July (summer), and October (fall) 2009. Variables were selected based on their relevance to patterns of coyote habitat use, as well as their utility in calibrating Landsat images of the study site and the likelihood that they would vary seasonally. Measured variables include: average percent live woody vegetation cover, average percent live grass cover, average percent live forb cover, and average woody plant height. Information on woody plant species with individuals greater than 0.5 m in height is also presented.

Core Areas: 

Data set ID: 

221

Additional Project roles: 

370
371

Keywords: 

Methods: 

Experimental Design: 

Vegetation surveys were carried out at grassland and shrubland sites located throughout the Sevilleta NWR. In 2008, two plot locations were randomly elected for each of twenty road based scat transects that were surveyed during the same field season. Vegetation plot location was determined by randomly selecting the following: a distance from the beginning of each mile long, road-based scat transect; side of the road (left or right); and a distance from the road (30-100m). 

One of the two plots associated with each of the 20 scat transects surveyed in 2008 was randomly selected and surveyed in each of the three seasons in which scat surveys were conducted in 2009. Two new vegetation plots, one for each of two new scat transects, were also surveyed in 2009.

Sampling Design: 

Each vegetation plot was circular with a 30m diameter intended to match the spatial scale of a Landsat satellite image pixel. In 2008, each of 40 plots was surveyed once between July 30th and August 20th, 2008.  At each plot, measurements were collected along 4 x 15m line intercept transects, one per cardinal direction, and in 5 x 1m^2 quadrats located at random distances and angles from the plot center. In 2009, half of these plots and two new ones were each surveyd three times, once in each of the following three months: April, July, October.  At each plot, measurements were collected along 4 x 15m line intercept transects, one per cardinal direction.

Field Methods: 

The coordinates of the center of each vegetation plot were determined using a GPS unit. In 2008, percent woody vegetation cover was measured, to the nearest 0.1m, along the 4 x 15m line intercept transects described in the sampling design section. This data was later combined to obtain estimates of percent woody cover for 2 x 30m transects that passed through the plot center and were perpendicular to one another such that one ran north-south and the other ran east-west. An attempt was made to measure percent cover only for live woody plants with a height of 0.5 m or greater. A plant was considered to be alive if it had green leaves on some part of it. The one exception to this rule was Gutierrezia sarothrae, for which percent cover was assessed for both plants with green leaves and plants with dead flowers but no green leaves. Each woody plant that crossed the line intercept transects was identified to species and, for each plant with a height of 0.5m or greater, the height was recorded and two perpendicular axes of the plant were measured. 5 interplant distances were measured from the first woody plant (0.5m or taller) that was encountered along each of the 4 line intercept transects in a plot. These distances were measured to the 5 closest woody plants that were also at least 0.5m tall and were within the plot and therefore represent nearest neighbor distances. When no woody plants were encountered along the line intercept transects, measurements were made from the woody plant closest to the first 1m^2 quadrat (described in sampling design section). Fewer than 5 distances were measured when there were fewer than 6 woody plants found within the plot boundaries. 

Measurements of percent grass cover were made in the 5 x 1m^2 quadrats described in the sampling design section. For each quadrat, the dominant grass, defined as the grass with the highest percent cover, was identified to genus and a small sample was collected. Two grass genera were recorded in cases where the two grasses had similar values for percent cover. A small sample of each woody plant species (excluding cholla and other cactus species) found within the plot was also collected. In 2009, percent live woody vegetation, grass and forb cover was measured, to the nearest 0.1m, along the 4 x 15m line intercept transects described in the sampling design section. This data was later combined to obtain estimates of percent woody, grass and forb cover for 2 x 30m transects that passed through the plot center and were perpendicular to one another such that one ran north-south and the other ran east-west. A plant was considered to be "live" if there were green leaves or stalks. For a given plant that intersected a line intercept transect, if only part of the plant had green leaves or stalks, then only that part was measured and included in the calculation of percent live vegetation cover. Each woody plant that crossed the line intercept transects was identified to species and, for each plant with a height of 0.5m or greater, the height was measured to the nearest 0.1m and recorded. As a result, a list of woody plant species with individuals of a height greater than or equal to 0.5m that crossed the line intercept transects is presented for each plot. A small sample of the dominant woody plant species (excluding cholla and other cactus species) and one of the dominant grass species found within the plot was collected. Dominance was determined based on vegetation data collected in 2008. In particular, dominance was defined as follows: woody plant species with the highest value for percent cover within the plot; grass species with the highest percentage cover in at least one of 5 1m^2 quadrats that was surveyed in each plot.

Laboratory Procedures: 

All plant samples were dried for 24 hours at 60 degrees Celsius and, in future, will be prepared and run through a stable carbon isotope analysis.

Data sources: 

sev221_coyotescatveg_20150615.csv

Quality Assurance: 

Data were recorded in the field and entered into a spreadsheet in Excel. Extraneous information, for example information on woody plants less than 0.5m in height, was removed. 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:

Amanda Boutz

Michael Donovan

Teresa Seamster

Terri Koontz

Kelly Bowman

Karles McQuade

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

Abstract: 

This study measured the population dynamics of coyotes 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. Coyotes were sampled via scat counts 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. Scat counts over a week period (number of scats/mile/day) in each season along the roads were used to calculate the densities of coyotes (number of coyotes per square kilometer). Results from 1992 to 2002 indicated that autumn was the peak density period of the year, with generally steady declines through the year until the following autumn. Coyote populations appeared to fluctuate seasonally, but remained relatively stable at 0.27 +/- 0.03 (SE) coyotes per km2 during summer periods (this likely represents the "breeding pair" density, during which coyote pairs have set up territories and are raising young, but the pups have not as yet joined the parents in foraging activities).

Core Areas: 

Data set ID: 

112

Additional Project roles: 

135
136

Keywords: 

Purpose: 

The purpose of the study was to assess the dynamics of coyote populations in the grasslands
and creosote shrublands of the Sevilleta NWR. Coyotes are important predators and omnivores in
these habitats, feeding on a wide variety of vertebrates, arthropods, and plants. Populations of
prey species may be controlled to some extent by coyote predation, in which case coyotes may have
significant influences on the biodiversity and species composition of the desert grassland
ecosystem.

Methods: 

Analytical Procedures

Density values were computed as numbers of individuals per square kilometer. According to F. Knowlton (see reference below), the relationship between absolute densities of coyotes (x-value, independent variable) and the number of scats per night per mile x 100 (y-value, dependent variable) is:

Y = 2.66 + 11.42X, r2 = 0.97, n = 8.

Transforming this equation for computing densities of coyotes from numbers of scats for each "leg" of the survey, and converting these values to numbers of coyotes per square kilometer, the coyote density equations for each survey "leg" are as follows:

D = Density of coyotes/km2

N = Total Number of Scats Collected/Leg after a 7-day period

Leg A (5.7 miles): D = [0.2195(N) - 0.2329]/2.59

Leg B (4.1 miles): D = [0.3052(N) - 0.2329]/2.59

Leg C (6.1 miles): D = [0.2052(N) - 0.2329]/2.59

Leg D (5.6 miles): D = [0.2235(N) - 0.2329]/2.59

Measurement Techniques

The number of scats deposited by coyotes per mile of roadway per day in a typical western basin-and-range landscape has been shown to be correlated with the absolute density of coyotes. Therefore, the objective was to measure the deposition rate of coyote scats on the roads of McKenzie Flats.

The process involved two samplings along the roads. The first sampling involved the "clearing" of scats from the 21.5 mile survey route, so as to initialize the roadway with zero scats. On the assigned day, the technician would drive an ATV slowly (less than 5 miles per hour) along the route. When a coyote scat was observed, the technician would stop and pick up the scat, placing it into a zip-lock plastic bag that was labeled with the date and the "leg" letter. Each "leg" was bagged separately. The odometer reading of the scat location was recorded on the data sheet. If more than one scat was observed at the same place, the number of scats was recorded as well. For health and safety, the technician wore gloves during this process, or used tongs or a small trowel to pick up the scats and place them into the bag. When using the ATV, the technician wore a safety helmet.

During the early sampling periods (1992 to 1993), prior to the acquisition of the ATV in 1994, scats were collected by two technicians in a pick-up truck. One technician would drive, and the other would ride on the engine hood above the bumper, and scan the road as the truck was driven slowly along the road. When a scat was observed, the driver would stop the truck while the rider would collect the scat. The same data were recorded as described above.

One week following the "road clearing" survey, a second collection took place. The scats were sampled in the same fashion as before, but each scat was placed individually in a labelled small zip-lock plastic bag. Again, odometer readings were taken at the point of collection. Multiple scats from the same location were placed in separate plastic bags.The scats were then returned to the field station, and placed in freezers for preservation pending analysis of dietary items.

Missing Data Values

Two data values were missing from the densities estimates due to road construction at the normal time of scat sampling. These were in the summer of 1993 (August) and the winter of 1994 (January). For completion of the coyote density graph, these two values were estimated from the trends observed in the other years (1992-1997). For the value in summer, 1993, the mean percentage decrease observed between the spring and summer values in other years was calculated, and that percentage (38.76%) was multiplied by the spring, 1993, density value of 0.79 coyotes/km2. Similarly, the winter, 1994, density value was estimated by calculating the percentage difference between the other years' winter and spring density values (40.75%) and multiplying the spring, 1994, value of 0.42 coyotes/km2 by 1.4075. Estimates of the standard errors were calculated in the same fashion, using the mean percentage standard error and multiplying it by the estimated means. The two seasonal values calculated using this method are noted in the data set below.

Sampling Design

The scats 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).

Data sources: 

sev112_coyotedens_20090106.txt

Maintenance: 

9-15-97; doc file created by Robert R. Parmenter.9-19-97; archived by Gregg MacKeigan as coyote_density_92-97.dbf.11-10-97; density data for October, 1997, entered and checked by R. Parmenter.12-26-00; density data for 2000 entered and checked by R. Parmenter.7-3-02; density data for 2001 and February and May entered and checked by R. Parmenter.8-2-02; density data for July, 2002, entered and checked by R. Parmenter.12-30-05; density data for 2002-2004 entered and checked, and final edits to the metadata file were made by R. Parmenter.8-2-02; density data for July, 2002, entered and checked by R. Parmenter.12-30-05; density data for 2002-2004 entered and checked, and final edits to the metadata file were made by R. Parmenter.

Quality Assurance: 

The data was visually checked for errors and missing values were commented on.

Additional information: 

Additional Information on the Data Collection Period

The samples (scats) were collected in winter, spring, summer, and fall, of each year. Scats were collected from the road once at the beginning of a collection period, and once at the end (usually, one week later) during each of these four seasons per year. Months of collection varied in some years, but generally the sampling was conducted in January, April, July, and October. The study began in January, 1992 and ended in July 1994. Sampled one week per season, four seasons per year.

Additional Study Area Information

Study Area Name: McKenzie Flats

Study Area Location: The northeast section of the Sevilleta, stretching from Black Butte south to the canyon and east to the Los Pinos. McKenzie Flats, between black Butte, 5 Points, Palo Duro Canyon, and the old McKenzie headquarters ranch building site.

Study Area Description: The study area consisted of the roads that cross McKenzie Flats. The length of the road used in the study was 21.5 miles. The individual sites of measurements were the locations of each individual scat during each sample period.

Elevation: 1615 m

Vegetation: The terrain was generally mixed-species desert grassland, dominated by black grama (Bouteloua eriopoda), blue grama grass (B. gracilis), sand muhly (Muhlenbergia arenicola), various drop seeds and sacatons (Sporobolus spp.), purple three-awn (Aristida purpurea), and burrow grass (Scleropogon brevifolia). Shrubs were common in Five Points area; these were creosote bush (Larrea tridentata) and snakeweed (Gutierrezia sarothrae).

Soils: Turney Series: fine-loamy, mixed, thermic Typic Calciorthids. Berino Series: fine-loamy, mixed, thermic Typic Haplargids.

Hydrology: Surface water only during rain events, no arroyos. Run on plain for Los Pinos Mountains.

Landform: McKenzie Flats is a broad, nearly flat grassland plain between the Los Pinos Mountains and the breaks on the east side of the Rio Grande.

Geology: Deep (20,000 ft) alluvial and eolian deposits.

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: McKenzie Flats encompasses an area of approximately 50 square miles. McKenzie Flats was one of the primary livestock grazing areas of the Sevilleta NWR. The ranch headquarters buildings and corrals were located at the junction of Legs C and D of this coyote survey. Cattle have been excluded from the site since 1974-76.

References

Knowlton, Frederick F. 1984. Feasibility of Assessing Coyote Abundance on Small Areas. Unpublished USDA Report, 14 pp.

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