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ESTIMATES OF THE DESERT TORTOISE (Gopherus Agazzizii) DOMESTIC POPULATION IN THE GREATER LAS VEGAS AREA, NEVADA
2018
PREPARED BYCENTER FOR BUSINESS AND ECONOMIC RESEARCH, UNLV
cber.unlv.edu
Copyright ©2018 by the UNLV Center for Business and Economic Research
The views expressed are those of the authors and do not necessarily represent those of the University of Nevada, Las Vegas or the Nevada System of Higher Education.
University of Nevada, Las Vegas Box 456002 4505 S. Maryland Parkway Las Vegas, Nevada 89154-6002 (702) 895-3191 [email protected] http://cber.unlv.edu
Domestic Desert Tortoise Population Estimates in the Greater Las Vegas Area
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The Estimates of the Desert Tortoise (Gopherus Agassizii) Domestic Population in the Greater Las Vegas Area, Nevada
Sponsorship: The Tortoise Group (Las Vegas, NV) sponsored this research study. The Executive Director of the Tortoise Group is Kobbe Shaw. Research Objective: This study estimates the domestic (with owners) desert tortoise population in the Greater Las Vegas area, Nevada. Methods: The study was conducted from March 2018 through November 2018. We define the geographical area of Greater Las Vegas to include Boulder City, North Las Vegas, Las Vegas, Henderson, Summerlin, and the Clark County unincorporated areas. This area largely captures metropolitan Las Vegas. The study employed a mail survey in English and Spanish, using a stratified (by ZIP Code) random sample of households. The Tortoise Group and CBER designed the questionnaire and the survey was distributed for CBER by Haines Direct, a nonprofit direct marketing firm located in North Canton, Ohio, using regular mail. Mail responses were collected, tabulated, and analyzed by CBER staff, using the STATA software described in the STATA Survey Data Reference Manual (Release 10). The issue of non-response bias, which dominates survey analysis, was dealt using the post-stratification methodology and three alternative weighting schemes. Results: We employed three weighting schemes (WS). The first (WS1) does not take into account the problem of non-response bias. The last two (WS2 and WS3) do account for the non-response bias and use the post-stratification methodology. WS2 corrects for misrepresentation of the population by ZIP Codes. WS3 addresses the misrepresentation both by ZIP Codes and household size. The results vary depending on the weighting scheme. The total count estimate of the desert tortoise population in Greater Las Vegas varies from 137,172 (standard deviation 23,486) in WS1, to 137,331 (standard deviation 22,424) in WS2, and 153,783 (standard deviation 44,755) in WS3. The estimates also vary by ZIP Codes. As a sub-product of the survey, we also obtained the estimates of the total domestic ownership of the cat and dog populations. Conclusions: An association was observed between the size of the desert tortoise domestic population and the size of the cat and dog pet population in the Greater Las Vegas area as follows: 1 tortoise =1.83 cats = 3.7 dogs (weighting scheme 1); 1 tortoise =1.97 cats = 3.79 dogs (weighting scheme 2); 1 tortoise =1.72 cats = 3.24 dogs (weighting scheme 3).
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CONTENTS
I. INTRODUCTION ..................................................................................................................................... 3
II. DATA COLLECTION and METHOLOGICAL ISSUES ....................................................................... 4
Data collection .......................................................................................................................................... 4
Non-response bias ..................................................................................................................................... 6
III. THE DATA ............................................................................................................................................. 8
Data Collection Tool ................................................................................................................................. 8
Population and Sample ............................................................................................................................. 8
IV. RESULTS and DISCUSSION ................................................................................................................ 9
Summary statistics .................................................................................................................................... 9
Population Analysis by ZIP Codes.......................................................................................................... 11
V. SUMMARY ........................................................................................................................................... 12
REFERENCES ........................................................................................................................................... 14
Figure 1: Number of households that own any pets in the survey sample .................................................. 16
Table 1: Results of pet population using WS1 ............................................................................................ 17
Table 2: Results for pet population using WS2 .......................................................................................... 17
Table 3: Results for pet population using WS3 .......................................................................................... 17
Table 4: Percent of households owned pets by ZIP Code ........................................................................... 18
Table 5: Results for domestic desert tortoise population by ZIP Code ....................................................... 20
Table 6: Results for pet cat population by ZIP Code .................................................................................. 22
Table 7: Results for pet dog population by ZIP Code ................................................................................. 24
Appendix A: ZIP-Code Maps for Highest and Lowest Desert Tortoise/Cat/Dog Populations................... 27
MAP A1: The Greater Las Vegas region by ZIP Codes ............................................................................. 27
MAP A2: ZIP Codes with the highest desert tortoise population ............................................................... 28
MAP A3: ZIP Codes with the lowest desert tortoise population ................................................................ 29
MAP A4: ZIP Codes with the highest cat population ................................................................................. 30
MAP A5: ZIP Codes with the lowest cat population .................................................................................. 31
MAP A6: ZIP Codes with the highest dog population ............................................................................... 32
MAP A7: ZIP Codes with the lowest dog population................................................................................. 33
Appendix B: Questionnaire ......................................................................................................................... 34
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I. INTRODUCTION Over the past several years, researchers have conducted various studies to estimate domestic
animal populations in different regions. These studies catered to socio-biological needs such as
promoting community disease control, encouraging the use of veterinary services, and providing
necessary information to the commercial food industries for domestic animals (Downes et al.,
2009; Butler and Bingham, 2000; Nasssar et al., 1984; Leslie et al., 1994; Baldock et al., 2003;
Patronek & Rowan, 1995). The availability of such information regarding the domestic population
of the desert tortoise (Gopherus agassizii) in the Greater Las Vegas area (see Map A1 in Appendix
A), Nevada, however, is extremely limited, practically unavailable, or obsolete. We define the
geographical area of the Greater Las Vegas to include Boulder City, North Las Vegas, Las Vegas,
Henderson, Summerlin, and the Clark County unincorporated areas. This definition largely
captures metropolitan Las Vegas.
This study estimates the total domestic population of desert tortoises in the Greater Las
Vegas area by random stratified sampling. Such an estimate provides important information on the
demographic dynamics of the desert tortoise in Greater Las Vegas. The Tortoise Group and CBER
designed the questionnaire and the survey was distributed for CBER by Haines Direct, a nonprofit
direct marketing firm located in North Canton, Ohio, using regular mail. Mail responses were
collected, tabulated, and analyzed by CBER staff, using the STATA software described in the
STATA Survey Data Reference Manual (Release 10). The questionnaire was written in both
English and Spanish. The research design placed the questions about the ownership of a desert
tortoise into a larger context of a pet survey. As a sub-product of the research design, we also
obtained estimates of the total population of domestic cats and dogs and derived a relationship
between the ownership of domestic desert tortoises and the ownership of domestic cats and dogs.
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The remainder of this study proceeds as follows. Section 2 discusses the process of data
collection, the methodology of the study, and the issues and problems related to non-response bias.
Section 3 provides the details on the questionnaire, the population of interest, and the sample
selection. Section 4 presents the results of the statistical analysis and the estimates of the domestic
desert tortoises in the Greater Las Vegas area. For robustness, we compare these estimates of desert
tortoises to the estimates of the total populations of domestic cats and dogs. That is, intuition
suggests that the populations of cats and dogs should exceed the population of desert tortoises. If
we find the reverse, then it raises concerns about our method of estimating the population of desert
tortoises. Finally, section 5 provides a brief summary.
II. DATA COLLECTION and METHOLOGICAL ISSUES Data collection We collect primary data to estimate pet populations in the Greater Las Vegas area. Primary data
can be collected from numerous data collection methods such as surveys, in-depth interviews,
focus groups, and observation. Selecting the most suitable method to gather data depends on the
objective of the study. For instance, in-depth interviews are most appropriate for a comprehensive
understanding of the issues. This method provides an opportunity to probe deeper from the
respondents’ answers. Similar to in-depth interviews, the focus group method also collects
comprehensive information about a particular program/project, such as how does it affect the
community and other stakeholders (Patton, 1990). These methods are expensive, resource
intensive, and time consuming, thus, only suitable when an in-depth understanding of the issues is
the main focus of the study. In contrast, surveys are suitable when the objective of the study is to
collect data from a large audience for a well-defined question. Thus, surveys are the most popular
data collection method for collecting descriptive data when an in-depth understanding is not the
main focus of the study (NSF, 2002).
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Surveys can be categorized into two broader groups, questionnaires and interviews.
Questionnaires are filled out by respondents, whereas interviews are conducted by the researcher
to gather information. Both interviews and questionnaires consist of closed- and open-ended
questions. Open-ended questions, however, are more common in interviews while closed-ended
questions are more common in questionnaires. Among the survey methods, questionnaires are the
best approach to collecting descriptive information. Several methods for administering a
questionnaire survey. Mail surveys are a most popular method among the others, such as telephone
and web surveys, since mail surveys are relatively cheaper and can address a broader group. Low
response rates and self-reporting bias, however, are the disadvantages of mail surveys (NSF, 2002).
Web-based surveys are most efficient in data collection and data recording compared to
mail surveys, since in web-surveys, the responses get directly recorded in a database. Therefore,
we can eliminate the time required to record data in a data base. Further, other merits of web-based
surveys include the ability to screen data and delete irrelevant responses. Web-based
questionnaires, however, are highly resource intensive. Therefore, they may not be practical in
certain resource-constrained environments.
The household drop-off survey is another method to administer a questionnaire survey. In
this method, the researcher delivers surveys to households and asks respondents to mail the
completed questionnaire. This method can possibly yield a higher response rate, as the researcher
gets the opportunity to interact with respondents and, therefore, he/she may convince respondents
to complete the survey and/or clarify any of the issues respondents have about the survey.
Household drop-off surveys, however, are more expensive and time consuming than mail surveys.
The group administered questionnaire is another method to implement a survey. In this
method, a person who conducts the survey, probably the researcher, distributes the survey to a
group of respondents. As the respondents complete the questionnaire, they can ask follow-up
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questions from the researcher so that the researcher can ensure that respondents understand the
questions correctly. Higher response rates are a major advantage of group administered
questionnaires compared to mail surveys. On the negative side, the group-administered
questionnaire method is more expensive than mail surveys. In addition, surveys can be
administered using telephones, either as an automated telephone survey or as a telephone interview
conducted by a trained resource person. In telephone interviews, respondents can ask follow-up
questions, whereas automated telephone interviews do not afford this option. Telephone interviews
must be extremely short as many telephone survey respondents do not like to be disturbed by a
telephone call. Thus, response rate could be lower, and the responses might not be reliable
(Trochim, 2006).
Weighing the costs and benefits of each aforementioned survey administration method, we
employed the mail survey method, which is the most popular, inexpensive, less resource intensive,
and the most accessible to a larger audience, to collect primary data on pet populations from
Southern Nevada households. As noted above, however, low-response rates are the major
drawback of this method.
Non-response bias As we just noted, low response rates are a major disadvantage of mail surveys. This can occur due
to either refusal, those who are in the sample do not like to respond, or non-contacts, sampled
individuals did not receive the survey for certain reasons (Merkle, 2011). Irrespective of the reason,
low-response rates engender a discrepancy between the characteristics of the respondents and the
characteristics of the non-respondents, which is technically known as the “non-response bias”
(Hager et al., 2003; Dilman, 2000). Non-response bias implies that certain groups of the population
are misrepresented during the data collection procedure. Thus, the collected sample cannot be
considered as random. Consequently, population estimates are erroneous (Berg, 2010).
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In the survey literature, researchers use numerous remedial measures to address non-
response bias. One such method compares respondent and non-respondent distributions, for
subgroups of a control variable, such as age, race, gender, and so on. If the response rates are
similar across groups, then the researcher concludes that no evidence for no-response bias exists
in the sample (Brick et al., 2002). Nevertheless, this method assumes that control variables are the
only possible causes of response propensity, which is not true in most situations. Some other
research attempts matching each individual in the sample with some external database (Assael &
Keon, 1982; Lin & Schaeffer, 1995). This method, however, relies on the availability of an external
database. In addition, other studies conduct follow-up studies to tackle non-response bias. In this
method, a survey is administered in several phases, aiming to increase the response rate in each
phase, then they compare estimates of each phase (Groves & Couper, 1998). This is a highly
resource-intensive and time-consuming method (Groves, 2006).
Alternatively, corrective weighting, using a socio-demographic variable, which is known
as adjusting for non-response weight by post-stratification, is one of the most popular methods to
address non-response bias in the survey literature (Dawson et al., 2014). This method involves a
two-step process: Step one - identify a set of control totals of the survey population, and step two
- calculate weights to adjust the sample totals to control totals. Thus, the researcher uses weights
to match sample totals to population totals. Mainly, researchers use population characteristics,
such as age and sex, to adjust the weights in National Surveys. One major advantage of this method
is that a large set of alternative estimators can be estimated. Thus, different estimators can be
compared with each other and the researcher can be confident about a particular estimator, if all
these population estimators generate similar magnitudes (Grove, 2006). Considering the above
merits, we use the post-stratification technique to address non-response bias.
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III. THE DATA Data Collection Tool Data collection tool, the survey questionnaire (see Appendix B for the questionnaire), is designed
in a short and concise manner to achieve a higher response rate. The questionnaire consists of four
main questions: (i) Does anyone in your house have pets? (ii) How many of the following pets do
you have? (iii) How many people live in the household, and (iv) In which ZIP Code do you live?
The second question asks respondents to state how many cats, dogs, birds, fish, horses, reptiles,
and desert tortoises that they have as pets. In addition to the above four questions, the first
paragraph of the questionnaire describes the purpose of the survey, and the last paragraph
acknowledges the respondent’s contribution and provides contact information to contact survey
administrators, if respondents have any questions. Since the Hispanic/Latino population exceeds
30 percent of the population in Greater Las Vegas, the survey questionnaire is printed two-sided,
one in English, and the other, the same questionnaire in Spanish.
Population and Sample The population of interest is the total number of households in the Greater Las Vegas area. We
select a sample of 38,202 households in The Greater Las Vegas area. The sample selection
procedure is as follows. First, we obtain the list of mailing addresses for Greater Las Vegas ZIP
Codes. Second, a 10-percent random sample of addresses are selected from the mailing list.
Consequently, the final sample adds up to a total of 38,202 households. According to Census 2016,
the total number of household units in the Greater Las Vegas area are 646,295, this implies, our
sample accounts for 5.9 percent of the total population in the Greater Las Vegas area.
Out of the total mailed surveys, we receive responses from 2,205 households. Thus, the
response rate of the survey is 5.8 percent. Out of the received responses, 57 questionnaires are
eliminated due to either not providing information for survey questions or providing unreliable
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information. For instance, some respondents stated ZIP Codes that are not located in the region.
Thus, the final sample summed to a total of 2,148 responses, which equals a 5.6 percent adjusted
response rate.
IV. RESULTS and DISCUSSION Summary statistics We define a pet dog as a dog that the households feed and consider as a pet by the household. Pet
cats, and pet tortoise are defined in the same manner (Downes et al., 2009). According to the
results, 66.8 percent of households own pets, and only 33.2 percent of households report that they
do not own any pets during the survey period (see Figure 1). Further, more than 22 percent of
households report owning more than one type of pet, for instance, they had pet dogs and pet cats.
Domestic (desert tortoises, cats, dogs) populations in the Greater Las Vegas Area
We calculate three types of weighting schemes (WS), using household demographic
characteristics, to estimate the total population. WS1 is the standard survey weighting scheme that
does not adjust for the problem of non-response bias, while WS2 and WS3 adjust the standard
survey weights to address this non-response bias.
WS1 is computed as follows:
WS1 = total number of households in the population
total number of households in the sample
WS1 does not consider that certain groups of the population can be misrepresented due to non-
response bias. Table 1 reports the domestic populations of cats, dogs, and desert tortoises estimated
using WS1. According to the results, the total domestic desert tortoise population, as well as the
pet cat and pet dog populations are 137,173, 250,897, and 507,950, respectively. Clearly, residents
of the Greater Las Vegas area more likely own pet dogs than pet cats or domestic desert tortoises.
The approximate ratio for the entire region shows that 1 tortoise =1.83 cats = 3.70 dogs.
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WS2 addresses the survey non-response bias. We use a post-stratification technique to
correct standard survey weights. Specifically, WS2 is used to correct for misrepresentation of
population by ZIP Codes and is computed as follows:
total number of households in a zipcode in the population
total number of households in a zipcode in the sample
WS2 = total number of households in the sample
total number of households in the population
Table 2 reports the results for the three populations estimated using WS2. The total
domestic populations for the domestic desert tortoises, pet cats, and pet dogs are 137,332, 270,474,
and 519,905, respectively. All three total population estimates obtained using WS2 are greater than
the estimates estimated using WS1. The percentage increase in estimator 2 compared to estimator
1, however, is extremely low, 0.1 percent, 7.2 percent, and 2.3 percent respectively for the
domestic desert tortoise, pet cat, and pet dog populations. The approximate ratio for the entire
region shows that 1 tortoise =1.97 cats = 3.79 dogs.
WS3 targets the misrepresentation of population both by ZIP Codes and household size. It
is well-known that domestic animals are an integral part of families. Thus, the household dynamics
may also influence the number of pets owned by a household. Considering this observation, we
use the following post-stratification weight to correct standard survey weights for ZIP Code and
household size:
total number of households with household size 1 in a zipcode in the populationtotal number of households with household size 1 in a zipcode in the sample
WS3 = total number of households with household size 1 in the sample
total number of households with household size 1 in the population
Table 3 reports the estimated results using WS3. Total number of desert tortoise, pet cat,
and pet dog populations are 153,784, 264,385, and 498,075, respectively. Surprisingly, the
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domestic desert tortoise population is greater for WS3 compared to both WS1 and WS2. The
results from WS3 imply a 10.7 percent increase compared to WS2 and a 10.8 percent increase
compared to WS1. On the other hand, the pet cat population is lower by 2.3 percent compared to
WS2, but is 5.1 percent higher compared to WS1. The pet dog population decreases by 4.4 percent
compared to WS2 and 2.0 percent compared to WS1.
Population Analysis by ZIP Codes We extend the analysis to ZIP Code level to inquire whether alternative demographics are
apparent by ZIP Code. Table 4 reports the percent of households that own pets by ZIP Code.
Accordingly, more than 50 percent of households owned pets in all ZIP Codes, except for ZIP
Codes 89044 (38.2%), 89102 (36.8%), and 89145 (47.5%).
Table 5 presents the total domestic desert tortoise population estimates (population means
and population totals) by ZIP Code according to each of the three weighting schemes. According
to these estimates, the highest population of desert tortoises resides in ZIP Code 89123 (24,035
desert tortoises). According to WS1, the second highest population of desert tortoises resides in
ZIP Code 89015 (14,069), followed by ZIP Codes 89121 (6,741), 89129 (6,448), and 89110
(6,155). Results from WS2 suggest that the first and second highest population of desert tortoises
reside in ZIP Codes 89123 (22,715) and 89110 (12,526), respectively, followed by ZIP Codes
89121 (10,919), 89015 (9,104), and 89129 (5,192). According to WS3, the first and second highest
population of desert tortoises reside in ZIP Codes 89123 (48,986) and 89121 (9,923), respectively,
followed by ZIP Codes 89015 (7,396), 89110 (7,126), and 89117 (5,660). It, thus, appears that ZIP
Codes 89123, 89015, 89110, and 89121 contain the highest desert tortoise populations. On the
other hand, the desert tortoise pet population is the lowest in ZIP Codes 89179, 89044, 89081, and
89143. Further, households in ZIP Codes 89030, 89102, 89115, 89128, 89142, 89166, and 89169
do not own pet tortoise according to the sample responses. See MAPs A2 and A3 in Appendix A.
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Table 6 reports the total pet cat population by ZIP Code. According to the WS1, the largest
cat population resides in ZIP Code 89117 (15,535) followed by 89108 (14,948). According to
WS2, however, the largest cat population resides in the ZIP Code 89108 (23,803) followed by
89117 (13,816).
Altogether, the cat population is higher in ZIP Codes 89117 and 89108. On the other hand,
ZIP Codes 89118, 89044, and 89179 were among the five ZIP Codes with the lowest cat population
according to the results obtained for all three weights. See MAPs A4 and A5 in Appendix A.
Table 7 reports the pet dog population by ZIP Code. According to WS1, the highest
population of pet dogs reside in ZIP Code 89131 (29,604) followed by tied 89123 (24,328) and
89129 (24,328) and then by 89031 (22,862) and 89015 (19,931). Both WS2 and WS3 suggest
that highest pet dog population resides in following five ZIP Codes, 89108, 89123, 89121,
89103, and 89031. Whereas, according to WS2 and WS3, the smallest pet dog populations reside
in ZIP Codes 89005, 89169, 89138, 89030, and 89179. WS1 suggests the smallest pet dog
population resides in ZIP Code 89169 followed by 89030, 89102, 89156, and 89142. See MAPs
A6 and A7 in Appendix A.
V. SUMMARY We estimate pet tortoise, pet cat, and pet dog populations in the Great Las Vegas area, Nevada,
adjusting for non-response bias. Specifically, we obtain three estimates for each pet tortoise, pet
cat, and pet dog population (i) using standard survey weights, (ii) using post-stratification weights
to address the sample mis-representation by ZIP Codes, and (iii) using post-stratification weights
to address the sample misrepresentation by ZIP Codes and household size.
The total pet tortoise population for WS1, WS2, and WS3 are 137,173, 137,332, and
153,784, respectively. The total pet cat population is 250,897, 270,474, and 264,385, respectively,
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for estimators using WS1, WS2, and WS3. Lastly, the total dog population is 507,950, 515,905,
and 498,075, respectively, for estimators using WS1, WS2, and WS3. Overall, the standard survey
weight underestimates the pet population in both the pet desert tortoise and pet cat populations,
but overestimates the pet dog population. Corrective weights by ZIP Codes inflate the population
estimator in all three cases; but, corrective weights for ZIP Codes and household size turn over the
effect for pet cat and pet dog populations. Interestingly, adjusted weights for ZIP Code and
household size increased the pet tortoise population by more than 12 percent compared to standard
survey weights. Table 8 summarizes the findings by ZIP Code.
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Figure 1: Number of households that own any pets in the survey sample
Note: Number of observations = 2,148
67%
33%
Yes No
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Table 1: Results of pet population using WS1
Survey Mean Survey Total
Mean St. Dev. Total St. Dev.
Tortoise 0.22 0.04 137,173 23,486
Cats 0.40 0.02 250,897 12,444
Dogs 0.81 0.02 507,950 13,839
Note: Number of observations = 2,148
Table 2: Results for pet population using WS2
Survey Mean Survey Total
Mean St. Dev. Total St. Dev.
Tortoise 0.21 0.03 137,332 22,424
Cats 0.42 0.02 270,474 15,907
Dogs 0.80 0.03 519,905 16,700
Note: Number of observations = 2,148
Table 3: Results for pet population using WS3
Survey Mean Survey Total
Mean St. Dev. Total St. Dev.
Tortoise 0.24 0.07 153,784 44,756
Cats 0.41 0.02 264,385 14,194
Dogs 0.78 0.03 498,075 16,822
Note: Number of observations = 2,148
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Table 4: Percent of households owned pets by ZIP Code
ZIP Code No of observations Percent of households with pets
89002 64 79.7
89005 44 56.8
89011 51 64.7
89012 68 69.1
89014 40 65
89015 77 72.7
89030 14 57.1
89031 77 79.2
89032 41 70.7
89044 68 38.2
89052 105 57.1
89074 82 62.2
89081 21 61.9
89102 19 36.8
89103 22 54.6
89107 30 73.3
89108 55 72.7
89110 35 62.9
89113 43 67.4
89115 18 61.1
89117 86 65.1
89118 15 73.3
89120 35 80
89121 50 66
89122 49 73.5
89123 82 78.1
89128 29 62.1
89129 84 76.2
89130 44 65.9
89131 108 75.9
89134 51 76.5
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Table 4: Percent of households owned pets by ZIP Code (continued)
ZIP Code No of observations Percent of households with pets
89135 43 76.7
89138 27 55.6
89139 32 56.3
89141 28 78.6
89142 20 55
89143 28 64.3
89144 34 76.5
89145 40 47.5
89146 15 86.7
89147 43 60.5
89148 42 57.1
89149 56 51.8
89156 18 66.7
89166 23 73.9
89169 3 100
89178 40 67.5
89179 13 84.6
89183 36 69.4 Note: Number of observations = 2,148
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Table 5: Results for domestic desert tortoise population by ZIP Code
WS1 WS2 WS3
Survey mean Survey total Survey mean Survey total Survey mean Survey total
Mean SD Total SD Mean SD Total SD Mean SD Total SD
Southern Nevada 0.22 0.04 137,173 23,486 0.21 0.03 137,332 22,424 0.24 0.07 153,784 44,756
89002 0.28 0.09 5,276 1,695 0.28 0.09 3,215 1,033 0.29 0.09 3,299 1,048
89005 0.27 0.16 3,517 2,027 0.27 0.16 1,706 983 0.26 0.12 1,599 782
89011 0.08 0.05 1,172 706 0.08 0.05 650 391 0.06 0.04 538 314
89012 0.12 0.04 2,345 889 0.12 0.04 1,520 576 0.11 0.04 1,465 579
89014 0.13 0.06 1,466 749 0.13 0.06 1,939 992 0.1 0.05 1,622 791
89015 0.62 0.48 14,069 10,864 0.62 0.48 9,104 7,030 0.51 0.37 7,396 5,436
89030 0 0 0 0 0 0 0 0 0 0 0 0
89031 0.19 0.07 4,397 1,507 0.19 0.07 3,878 1,329 0.13 0.05 2,667 904
89032 0.24 0.17 2,931 2,089 0.24 0.17 3,269 2,330 0.18 0.11 2,356 1,469
89044 0.01 0.01 293 293 0.01 0.01 119 119 0.01 0.01 88 88
89052 0.11 0.05 3,517 1,462 0.11 0.05 2,321 964 0.1 0.04 2,045 848
89074 0.13 0.07 3,224 1,758 0.13 0.07 2,548 1,389 0.12 0.06 2,209 1,148
89081 0.05 0.05 293 293 0.05 0.05 478 478 0.04 0.04 401 368
89102 0 0 0 0 0 0 0 0 0 0 0 0
89103 0.09 0.09 586 586 0.09 0.09 1,940 1,940 0.08 0.07 1,806 1,510
89107 0.2 0.09 1,759 777 0.2 0.09 2,485 1,099 0.19 0.1 2,362 1,197
89108 0.18 0.08 2,931 1,261 0.18 0.08 4,667 2,008 0.22 0.1 5,519 2,681
89110 0.6 0.34 6,155 3,473 0.6 0.34 12,526 7,068 0.34 0.18 7,126 3,741
89113 0.16 0.09 2,052 1,104 0.16 0.09 1,679 903 0.15 0.08 1,578 870
89115 0 0 0 0 0 0 0 0 0 0 0 0
89117 0.2 0.09 4,983 2,159 0.2 0.09 4,432 1,920 0.25 0.13 5,660 2,930
89118 0.4 0.27 1,759 1,198 0.4 0.27 3,252 2,216 0.36 0.2 2,952 1,643
89120 0.37 0.15 3,810 1,521 0.37 0.15 3,397 1,357 0.28 0.1 2,592 927
89121 0.46 0.19 6,741 2,752 0.46 0.19 10,919 4,458 0.42 0.15 9,923 3,638
89122 0.14 0.09 2,052 1,324 0.14 0.09 2,511 1,621 0.18 0.11 3,146 1,946
89123 1 0.78 24,035 18,796 1 0.78 22,715 17,764 2.16 1.91 48,986 43,314
89128 0 0 0 0 0 0 0 0 0 0 0 0
89129 0.26 0.07 6,448 1,823 0.26 0.07 5,192 1,468 0.26 0.08 5,094 1,583
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Table 5: Results for domestic desert tortoise population by ZIP Code (continued)
WS1 WS2 WS3
Survey mean Survey total Survey mean Survey total Survey mean Survey total
Mean SD Total SD Mean SD Total SD Mean SD Total SD
89130 0.27 0.18 3,517 2,272 0.27 0.18 3,426 2,213 0.32 0.22 3,986 2,734
89131 0.14 0.03 4,397 1,058 0.14 0.03 2,184 526 0.14 0.04 2,134 562
89134 0.14 0.06 2,052 839 0.14 0.06 1,603 656 0.15 0.06 1,771 746
89135 0.09 0.06 1,172 704 0.09 0.06 1,000 600 0.07 0.04 701 399
89138 0.19 0.13 1,466 1,038 0.19 0.13 927 657 0.23 0.14 891 566
89139 0.06 0.04 586 408 0.06 0.04 737 513 0.08 0.05 929 603
89141 0.25 0.14 2,052 1,166 0.25 0.14 2,407 1,367 0.27 0.16 2,638 1,542
89142 0 0 0 0 0 0 0 0 0 0 0 0
89143 0.04 0.04 293 293 0.04 0.04 146 146 0.05 0.05 208 196
89144 0.18 0.08 1,759 784 0.18 0.08 1,259 561 0.13 0.06 892 448
89145 0.13 0.06 1,466 749 0.13 0.06 1,180 604 0.13 0.07 1,272 705
89146 0.47 0.4 2,052 1,762 0.47 0.4 2,992 2,569 0.37 0.3 1,638 1,333
89147 0.12 0.06 1,466 751 0.12 0.06 2,196 1,126 0.1 0.05 1,826 901
89148 0.21 0.17 2,638 2,120 0.21 0.17 3,466 2,785 0.19 0.14 3,023 2,325
89149 0.07 0.06 1,172 922 0.07 0.06 935 735 0.06 0.04 723 547
89156 0.17 0.12 879 640 0.17 0.12 1,509 1,098 0.24 0.15 1,847 1,116
89166 0 0 0 0 0 0 0 0 0 0 0 0
89169 0 0 0 0 0 0 0 0 0 0 0 0
89178 0.1 0.05 1,172 563 0.1 0.05 1,168 561 0.1 0.05 1,172 549
89179 0.15 0.1 586 397 0.15 0.1 261 176 0.14 0.08 209 126
89183 0.25 0.11 2,638 1,142 0.25 0.11 3,474 1,504 0.4 0.23 5,493 3,160 Note: Number of observations = 2,148
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Table 6: Results for pet cat population by ZIP Code
WS1 WS2 WS3
Survey mean Survey total Survey mean Survey total Survey mean Survey total
Mean SD Total SD Mean SD Total SD Mean SD Total SD
Southern Nevada 0.4 0.02 250,897 12,444 0.42 0.02 270,474 15,907 0.41 0.02 264,385 14,194
89002 0.34 0.1 6,448 1,969 0.34 0.1 3,929 1,200 0.34 0.1 3,902 1,155
89005 0.2 0.1 2,638 1,228 0.2 0.1 1,280 596 0.25 0.13 1,535 836
89011 0.25 0.08 3,810 1,172 0.25 0.08 2,113 650 0.25 0.07 2,084 595
89012 0.25 0.07 4,983 1,345 0.25 0.07 3,230 872 0.28 0.07 3,672 917
89014 0.48 0.16 5,569 1,829 0.48 0.16 7,369 2,421 0.44 0.14 6,885 2,168
89015 0.44 0.09 9,966 2,107 0.44 0.09 6,449 1,363 0.52 0.11 7,626 1,648
89030 0.5 0.27 2,052 1,118 0.5 0.27 6,561 3,574 0.57 0.29 7,538 3,835
89031 0.39 0.09 8,793 2,051 0.39 0.09 7,755 1,809 0.43 0.11 8,587 2,179
89032 0.24 0.1 2,931 1,244 0.24 0.1 3,269 1,387 0.3 0.12 4,052 1,574
89044 0.04 0.03 879 651 0.04 0.03 357 264 0.09 0.05 611 367
89052 0.43 0.1 13,190 3,113 0.43 0.1 8,703 2,054 0.41 0.1 8,252 1,986
89074 0.29 0.07 7,035 1,693 0.29 0.07 5,559 1,338 0.37 0.08 7,119 1,493
89081 0.29 0.14 1,759 865 0.29 0.14 2,867 1,409 0.28 0.14 2,797 1,434
89102 0.58 0.31 3,224 1,720 0.58 0.31 8,117 4,331 0.53 0.23 7,426 3,163
89103 0.5 0.23 3,224 1,515 0.5 0.23 10,668 5,013 0.39 0.15 8,406 3,178
89107 0.4 0.14 3,517 1,236 0.4 0.14 4,970 1,747 0.44 0.16 5,500 1,956
89108 0.93 0.28 14,948 4,561 0.93 0.28 23,803 7,262 0.82 0.27 21,093 6,924
89110 0.17 0.09 1,759 891 0.17 0.09 3,579 1,813 0.11 0.06 2,382 1,248
89113 0.49 0.21 6,155 2,698 0.49 0.21 5,036 2,207 0.55 0.26 5,656 2,721
89115 0.22 0.13 1,172 682 0.22 0.13 3,873 2,252 0.21 0.1 3,681 1,807
89117 0.62 0.13 15,535 3,366 0.62 0.13 13,816 2,994 0.6 0.13 13,491 2,992
89118 0.2 0.11 879 470 0.2 0.11 1,626 869 0.21 0.11 1,706 896
89120 0.57 0.18 5,862 1,894 0.57 0.18 5,227 1,689 0.69 0.22 6,309 2,041
89121 0.58 0.14 8,500 2,097 0.58 0.14 13,767 3,397 0.55 0.12 13,159 2,947
89122 0.43 0.11 6,155 1,567 0.43 0.11 7,532 1,918 0.38 0.09 6,665 1,572
89123 0.44 0.1 10,552 2,506 0.44 0.1 9,972 2,368 0.36 0.08 8,127 1,867
89128 0.59 0.22 4,983 1,911 0.59 0.22 8,475 3,250 0.61 0.23 8,821 3,258
89129 0.36 0.09 8,793 2,232 0.36 0.09 7,080 1,797 0.36 0.09 7,185 1,801
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Table 6: Results for pet cat population by ZIP Code (continued)
WS1 WS2 WS3
Survey mean Survey total Survey mean Survey total Survey mean Survey total
Mean SD Total SD Mean SD Total SD Mean SD Total SD
89130 0.48 0.13 6,155 1,703 0.48 0.13 5,996 1,659 0.46 0.12 5,757 1,462
89131 0.39 0.08 12,310 2,458 0.39 0.08 6,115 1,221 0.43 0.09 6,812 1,455
89134 0.35 0.12 5,276 1,816 0.35 0.12 4,122 1,419 0.36 0.13 4,177 1,544
89135 0.6 0.15 7,621 1,928 0.6 0.15 6,500 1,645 0.63 0.15 6,796 1,658
89138 0.37 0.15 2,931 1,206 0.37 0.15 1,854 763 0.39 0.16 1,535 631
89139 0.25 0.1 2,345 942 0.25 0.1 2,948 1,184 0.23 0.09 2,719 1,093
89141 0.32 0.14 2,638 1,121 0.32 0.14 3,094 1,315 0.29 0.12 2,749 1,120
89142 0.5 0.26 2,931 1,504 0.5 0.26 5,288 2,712 0.4 0.18 4,251 1,919
89143 0.39 0.16 3,224 1,290 0.39 0.16 1,608 644 0.44 0.17 1,814 711
89144 0.32 0.13 3,224 1,312 0.32 0.13 2,307 939 0.31 0.12 2,184 823
89145 0.3 0.13 3,517 1,525 0.3 0.13 2,833 1,228 0.29 0.12 2,781 1,157
89146 0.4 0.29 1,759 1,273 0.4 0.29 2,564 1,856 0.42 0.24 1,866 1,067
89147 0.42 0.14 5,276 1,741 0.42 0.14 7,907 2,609 0.39 0.12 7,392 2,322
89148 0.4 0.14 4,983 1,733 0.4 0.14 6,547 2,277 0.38 0.12 6,090 1,954
89149 0.36 0.1 5,862 1,643 0.36 0.1 4,675 1,310 0.35 0.09 4,549 1,190
89156 0.44 0.15 2,345 766 0.44 0.15 4,024 1,314 0.55 0.06 4,120 490
89166 0.48 0.23 3,224 1,520 0.48 0.23 2,436 1,149 0.46 0.14 2,359 737
89169 0.33 0.33 293 293 0.33 0.33 2,997 2,997 0.64 . 4,019 .
89178 0.48 0.13 5,569 1,570 0.48 0.13 5,548 1,564 0.45 0.12 5,213 1,393
89179 0.38 0.18 1,466 687 0.38 0.18 652 306 0.32 0.15 483 226
89183 0.25 0.09 2,638 975 0.25 0.09 3,474 1,284 0.18 0.07 2,453 1,013 Note: Number of observations = 2,148
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Table 7: Results for pet dog population by ZIP Code
WS1 WS2 WS3
Survey mean Survey total Survey mean Survey total Survey mean Survey total
Mean SD Total SD Mean SD Total SD Mean SD Total SD
Southern Nevada 0.81 0.02 507,950 13,839 0.8 0.03 519,905 16,700 0.78 0.03 498,075 16,822
89002 0.94 0.12 17,586 2,321 0.94 0.12 10,717 1,415 0.9 0.12 10,236 1,321
89005 0.55 0.11 7,035 1,480 0.55 0.11 3,412 718 0.51 0.09 3,205 578
89011 0.76 0.14 11,431 2,118 0.76 0.14 6,339 1,174 0.66 0.12 5,448 1,009
89012 0.81 0.12 16,121 2,297 0.81 0.12 10,448 1,489 0.8 0.12 10,358 1,593
89014 0.63 0.13 7,328 1,495 0.63 0.13 9,696 1,979 0.6 0.13 9,294 2,059
89015 0.88 0.12 19,931 2,671 0.88 0.12 12,897 1,728 0.75 0.1 10,937 1,432
89030 0.14 0.14 586 586 0.14 0.14 1,875 1,875 0.12 0.11 1,568 1,409
89031 1.01 0.12 22,862 2,720 1.01 0.12 20,164 2,399 1.05 0.13 20,824 2,655
89032 1.1 0.22 13,190 2,681 1.1 0.22 14,712 2,990 0.98 0.21 13,201 2,805
89044 0.53 0.11 10,552 2,228 0.53 0.11 4,278 903 0.51 0.1 3,584 733
89052 0.45 0.07 13,776 2,123 0.45 0.07 9,090 1,401 0.41 0.06 8,385 1,311
89074 0.63 0.09 15,241 2,107 0.63 0.09 12,045 1,665 0.65 0.08 12,358 1,546
89081 0.71 0.21 4,397 1,284 0.71 0.21 7,168 2,094 0.61 0.16 6,136 1,603
89102 0.42 0.19 2,345 1,070 0.42 0.19 5,903 2,694 0.66 0.2 9,195 2,738
89103 0.95 0.26 6,155 1,669 0.95 0.26 20,366 5,523 0.98 0.37 20,936 7,816
89107 0.83 0.17 7,328 1,466 0.83 0.17 10,355 2,071 0.83 0.14 10,321 1,759
89108 0.96 0.13 15,535 2,172 0.96 0.13 24,737 3,459 0.99 0.15 25,485 3,822
89110 0.94 0.19 9,672 1,970 0.94 0.19 19,684 4,009 0.78 0.2 16,320 4,162
89113 0.6 0.13 7,621 1,577 0.6 0.13 6,235 1,290 0.52 0.11 5,412 1,175
89115 0.83 0.25 4,397 1,297 0.83 0.25 14,523 4,285 0.81 0.22 14,082 3,805
89117 0.74 0.11 18,759 2,772 0.74 0.11 16,684 2,465 0.68 0.1 15,213 2,337
89118 0.93 0.27 4,103 1,172 0.93 0.27 7,588 2,168 0.83 0.23 6,738 1,884
89120 1.37 0.35 14,069 3,620 1.37 0.35 12,544 3,228 1.25 0.24 11,391 2,177
89121 0.86 0.19 12,603 2,809 0.86 0.19 20,414 4,550 0.79 0.16 18,643 3,809
89122 0.84 0.14 12,017 2,067 0.84 0.14 14,706 2,529 0.83 0.14 14,615 2,521
89123 1.01 0.12 24,328 2,813 1.01 0.12 22,992 2,659 0.87 0.1 19,721 2,298
89128 1.07 0.26 9,086 2,189 1.07 0.26 15,455 3,724 1.16 0.33 16,733 4,784
89129 0.99 0.12 24,328 2,992 0.99 0.12 19,589 2,410 0.92 0.12 18,252 2,282
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Table 7: Results for pet dog population by ZIP Code (continued)
WS1 WS2 WS3
Survey mean Survey total Survey mean Survey total Survey mean Survey total
Mean SD Total SD Mean SD Total SD Mean SD Total SD
89130 0.73 0.15 9,379 1,892 0.73 0.15 9,137 1,843 0.74 0.12 9,289 1,524
89131 0.94 0.09 29,604 2,953 0.94 0.09 14,706 1,467 0.93 0.11 14,574 1,731
89134 0.82 0.13 12,310 1,905 0.82 0.13 9,618 1,488 0.83 0.13 9,666 1,516
89135 0.74 0.13 9,379 1,629 0.74 0.13 8,000 1,390 0.74 0.12 8,008 1,340
89138 0.56 0.18 4,397 1,422 0.56 0.18 2,782 900 0.58 0.17 2,300 685
89139 0.56 0.13 5,276 1,259 0.56 0.13 6,634 1,583 0.5 0.1 5,870 1,235
89141 1.36 0.21 11,138 1,751 1.36 0.21 13,065 2,054 1.51 0.21 14,585 1,990
89142 0.55 0.22 3,224 1,309 0.55 0.22 5,816 2,362 0.4 0.15 4,198 1,568
89143 0.96 0.2 7,914 1,661 0.96 0.2 3,948 829 0.99 0.22 4,060 884
89144 0.85 0.13 8,500 1,339 0.85 0.13 6,083 958 1.03 0.13 7,348 952
89145 0.6 0.15 7,035 1,721 0.6 0.15 5,665 1,386 0.59 0.16 5,555 1,527
89146 1.2 0.34 5,276 1,499 1.2 0.34 7,693 2,185 1.03 0.28 4,610 1,258
89147 0.72 0.14 9,086 1,795 0.72 0.14 13,618 2,691 0.71 0.13 13,331 2,512
89148 0.74 0.16 9,086 1,970 0.74 0.16 11,938 2,589 0.71 0.15 11,438 2,476
89149 0.59 0.1 9,672 1,608 0.59 0.1 7,714 1,282 0.55 0.09 7,146 1,149
89156 0.61 0.23 3,224 1,217 0.61 0.23 5,534 2,088 0.83 0.42 6,293 3,207
89166 1.04 0.23 7,035 1,556 1.04 0.23 5,315 1,176 1.01 0.22 5,126 1,108
89169 0.33 0.33 293 293 0.33 0.33 2,997 2,997 0.18 0.15 1,110 962
89178 0.78 0.14 9,086 1,652 0.78 0.14 9,051 1,646 0.78 0.14 9,053 1,593
89179 1 0.34 3,810 1,294 1 0.34 1,694 575 1.04 0.28 1,552 412
89183 1.03 0.21 10,845 2,164 1.03 0.21 14,283 2,849 1.03 0.19 14,372 2,676 Note: Number of observations = 2,148
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Table 8: Summary: Highest and Lowest Populations by ZIP Code and Communities
Domestic Desert Tortoise Population Pet Cat Population Pet Dog Population
Highest● Lowest● Highest● Lowest● Highest● Lowest●
89110 89143 89108 89118 89031 89030
89121 89081 89117 89179 89123 89169
89123 89179 89044
89015 89044
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Appendix A: ZIP-Code Maps for Highest and Lowest Desert Tortoise/Cat/Dog Populations
MAP A1: The Greater Las Vegas region by ZIP Codes
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MAP A2: ZIP Codes with the highest desert tortoise population
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MAP A3: ZIP Codes with the lowest desert tortoise population
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MAP A4: ZIP Codes with the highest cat population
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MAP A5: ZIP Codes with the lowest cat population
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MAP A6: ZIP Codes with the highest dog population
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MAP A7: ZIP Codes with the lowest dog population
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Appendix B: Questionnaire
(Voltea la página para español) Dear Clark County Resident, Pets are an important part of people’s homes and lives, Tortoise Group (a local non-profit organization) is attempting to understand the demographics of the pet population in order to better serve our state’s reptile, the desert tortoise. It is legal and lawful to have a desert tortoise as a pet (Nevada Administrative Code, NAC503.093); this survey is completely anonymous, and we encourage everyone to fill out the questionnaire and return it even if you don’t have a tortoise.
1. Does anyone in your house have any pets? Yes/No (if no, go to Question #3)
2. How many of the following pets do you have? a. Cat _____ b. Dog _____ c. Bird _____ d. Fish _____ e. Horse _____ f. Reptile _____ g. Tortoise (if no, go to Question #3) _____
A. How many desert tortoises (estimates are OK if total is unknown) live with you? _______
B. How much do you spend on tortoise food per month? _______ C. Have you ever taken your tortoise(s) to the vet? _______ D. Do you know anyone in Clark County
that has a tortoise as a pet? _______ 3. How many people live in your household? _______ 4. In which ZIP Code do you live? _______
Thank you for participating. This survey is anonymous. If you have tortoises as pets, we encourage you to register them at www.tortoisegroup.org – you can register your tortoises (even if you have more than one) anonymously as well. Registration of tortoises is encouraged and will keep your pets legal no matter what changes in the law occur in the future. Regards, Kobbe Shaw Executive Director, Tortoise Group
Estimado Residente de Clark County, Las mascotas son partes importantes de nuestras casas y vidas, Tortoise Group (una organización sin fines de lucro) está intentando comprender los datos demográficos de la población de mascotas para servir mejor al reptil de nuestro estado, la tortuga de tierra. Es legal tener un tortuga de tierra como una mascota (Código Administrativo de Nevada, NAC503.093); esta encuesta es completamente anónima y los animamos a que completen la encuesta y la devuelvan, incluso si no tiene una tortuga.
1. ¿Alguién en su casa tiene una mascota? Sí/No (si no, vaya a Pregunta 3)
2. ¿Cuántas de estas mascotas tiene? a. Gato _____ b. Perro _____ c. Pájaro _____ d. Pez _____ e. Caballo _____ f. Reptil _____ g. Tortuga de tierra (si no, vaya a Pregunta 3)
A. ¿Cuántas tortugas viven con usted (estimados están bien si no sabe)? _____ B. ¿Cuánto paga cada mes por comida de tortuga? _____ C. ¿Ha llevado su tortuga al veterinario? _____
3. ¿Usted conoce a alguien en Clark County que tenga una tortuga como mascota? _____ 4. ¿Cuántas personas viven en su casa? _____ 5. ¿En que código postal vive usted? _____
Gracias por participar. Esta encuesta es anónima. Si usted tiene tortugas como mascotas, los animamos a que las registren en www.tortoisegroup.org - usted tambien puede registrar a sus tortugas anónimamente (incluso si tiene más de una). La registración de sus tortugas de tierra es importante para mantener sus mascotas legalmente aunque cambien las leyes en el futuro. Saludos, Kobbe Shaw Director Ejecutivo, Tortoise Group