Abstract
We developed rainproof track stations to index sciurid abundance. Track stations were effective at detecting presence of a species and provided a useful index of abundance in two validation efforts. In the more rigorous validation, we documented the correlation of two indices of abundance (our track index and catch-per-unit-effort, CPUE) with population size of Abert's squirrels (Sciurus aberti) as estimated by mark-recapture methods on eight 60-ha plots in April and August 1996. The track index (number of stations visited) was correlated highly with estimated population size in both April (r = 0.983) and August (r = 0.924). CPUE, as measured by the cumulative number of squirrels captured in the first day and first 2 days of the trapping effort, performed as well (r = 0.905 in April and r = 0.945 in August) as the track index. We also examined the correlation between these two indices for chipmunks (Tamias), golden-mantled ground squirrels (Spermophilus lateralis), rock squirrels (S. variegatus), and Abert's squirrels by double-sampling 30 plots (2.25 ha each) for diurnal sciurids in 1994 and 1995. The track index and CPUE were correlated highly for chipmunks (r = 0.815), golden-mantled ground squirrels (r = 0.881), rock squirrels (r = 0.868), and Abert's squirrels (r = 0.926). Similarity of regression slopes suggested that the track index was valid across seasons. Both the trap index and CPUE were less powerful statistically than mark-recapture estimates in detecting differences among plots and between seasons but did detect large differences without unacceptable Type I errors. Compared to live-trapping, track stations provided results in less time, were less expensive and easier to deploy in the field, caused no mortality to animals, and eliminated exposure of technicians to diseases transmitted by rodents.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 352-359 |
| Number of pages | 8 |
| Journal | Journal of Mammalogy |
| Volume | 79 |
| Issue number | 1 |
| State | Published - Feb 1998 |
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Keywords
- Abert's squirrel
- Abundance
- Population estimation
- Sciurid
- Sciurus aberti
- Spermophilus
- Tamias
- Track stations
ASJC Scopus subject areas
- Animal Science and Zoology
Cite this
Use of track stations to index abundance of sciurids. / Drennan, Joseph E.; Beier, Paul; Dodd, Norris L.
In: Journal of Mammalogy, Vol. 79, No. 1, 02.1998, p. 352-359.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Use of track stations to index abundance of sciurids
AU - Drennan, Joseph E.
AU - Beier, Paul
AU - Dodd, Norris L.
PY - 1998/2
Y1 - 1998/2
N2 - We developed rainproof track stations to index sciurid abundance. Track stations were effective at detecting presence of a species and provided a useful index of abundance in two validation efforts. In the more rigorous validation, we documented the correlation of two indices of abundance (our track index and catch-per-unit-effort, CPUE) with population size of Abert's squirrels (Sciurus aberti) as estimated by mark-recapture methods on eight 60-ha plots in April and August 1996. The track index (number of stations visited) was correlated highly with estimated population size in both April (r = 0.983) and August (r = 0.924). CPUE, as measured by the cumulative number of squirrels captured in the first day and first 2 days of the trapping effort, performed as well (r = 0.905 in April and r = 0.945 in August) as the track index. We also examined the correlation between these two indices for chipmunks (Tamias), golden-mantled ground squirrels (Spermophilus lateralis), rock squirrels (S. variegatus), and Abert's squirrels by double-sampling 30 plots (2.25 ha each) for diurnal sciurids in 1994 and 1995. The track index and CPUE were correlated highly for chipmunks (r = 0.815), golden-mantled ground squirrels (r = 0.881), rock squirrels (r = 0.868), and Abert's squirrels (r = 0.926). Similarity of regression slopes suggested that the track index was valid across seasons. Both the trap index and CPUE were less powerful statistically than mark-recapture estimates in detecting differences among plots and between seasons but did detect large differences without unacceptable Type I errors. Compared to live-trapping, track stations provided results in less time, were less expensive and easier to deploy in the field, caused no mortality to animals, and eliminated exposure of technicians to diseases transmitted by rodents.
AB - We developed rainproof track stations to index sciurid abundance. Track stations were effective at detecting presence of a species and provided a useful index of abundance in two validation efforts. In the more rigorous validation, we documented the correlation of two indices of abundance (our track index and catch-per-unit-effort, CPUE) with population size of Abert's squirrels (Sciurus aberti) as estimated by mark-recapture methods on eight 60-ha plots in April and August 1996. The track index (number of stations visited) was correlated highly with estimated population size in both April (r = 0.983) and August (r = 0.924). CPUE, as measured by the cumulative number of squirrels captured in the first day and first 2 days of the trapping effort, performed as well (r = 0.905 in April and r = 0.945 in August) as the track index. We also examined the correlation between these two indices for chipmunks (Tamias), golden-mantled ground squirrels (Spermophilus lateralis), rock squirrels (S. variegatus), and Abert's squirrels by double-sampling 30 plots (2.25 ha each) for diurnal sciurids in 1994 and 1995. The track index and CPUE were correlated highly for chipmunks (r = 0.815), golden-mantled ground squirrels (r = 0.881), rock squirrels (r = 0.868), and Abert's squirrels (r = 0.926). Similarity of regression slopes suggested that the track index was valid across seasons. Both the trap index and CPUE were less powerful statistically than mark-recapture estimates in detecting differences among plots and between seasons but did detect large differences without unacceptable Type I errors. Compared to live-trapping, track stations provided results in less time, were less expensive and easier to deploy in the field, caused no mortality to animals, and eliminated exposure of technicians to diseases transmitted by rodents.
KW - Abert's squirrel
KW - Abundance
KW - Population estimation
KW - Sciurid
KW - Sciurus aberti
KW - Spermophilus
KW - Tamias
KW - Track stations
UR - http://www.scopus.com/inward/record.url?scp=0005241018&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0005241018&partnerID=8YFLogxK
M3 - Article
AN - SCOPUS:0005241018
VL - 79
SP - 352
EP - 359
JO - Journal of Mammalogy
JF - Journal of Mammalogy
SN - 0022-2372
IS - 1
ER -