1 2 3 4 5 6
Using Multiple Survey Methods to Detect Terrestrial Reptiles and
7
Mammals: What are the Most Successful and Cost Efficient
8
Combinations?
9 10 11 12 13 14 15
Jenni Garden*1,2, Clive McAlpine1,2, Darryl Jones3, Hugh Possingham2 1
School of Geography, Planning and Architecture, The University of Queensland, St Lucia, Brisbane, Qld, 2The Ecology Centre, The University of Queensland, St Lucia, Brisbane, Qld, Centre for Innovative Conservation Strategies, Griffith University, Nathan, Brisbane, Qld
16 17 18
* Corresponding Author: C/- School of Geography, Planning and Architecture, The University of Queensland, St Lucia, 4072, Qld, Australia. (Email:
[email protected]). Ph: 0403 778 963. Fax: (07) 3365 6899
19 20 21
Running Title: Cost-effective fauna surveys
22 23 24 25 26 27 28 29 30 31 32 33 34
1
35
Abstract
36
The selection of survey methods for wildlife surveys is a critical decision that will
37
influence the accuracy and comprehensiveness of the research outcomes. The choice
38
of methods is commonly based on the species of interest, yet is often limited by the
39
project budget.
40
various survey techniques for detecting terrestrial mammal and reptile species, none
41
have provided a quantitative analysis of the costs associated with different methods.
42
We compared the detection success and cost efficiency of six survey methods for
43
detecting the occurrence of terrestrial mammal and reptile species in urban bushland
44
remnants of Brisbane City, Queensland. We detected a total of 19 target reptile
45
species (8 families) and 9 target mammal species (3 families). Cage traps or Elliott
46
traps coupled with hair funnels were the most cost-effective methods for detecting
47
ground-dwelling mammals, with the success of cage or Elliott traps dependent on
48
s pe c i e s ’bodys i z e s . Pi t -fall traps and/or direct observations were the most cost
49
effective methods for detecting reptiles, with the effectiveness of each method
50
de pe ndi ngoft hes pe c i e s ’body -size and behaviour.
Although several studies have investigated the effectiveness of
51 52
Key words: Cage trap, Elliott trap, pit-fall trap, hair funnel, direct observation, scat
53
analysis, Brisbane
54
2
55 56
Introduction Ma na g i ngAus t r a l i a ’ st e r r e s t r i a lha bi t a t sf orma mma la ndr e pt i l ec ons e r va t i on
57
requires a thorough knowledge of the composition and distribution of species within
58
and across the habitats of interest.
59
abundance have long been used to acquire such knowledge. For terrestrial mammal
60
and reptile species, a variety of survey methods have been used by researchers to
61
determine occurrence and abundance. These methods have been specifically designed
62
t ot a r ge tpa r t i c ul a rs pe c i e sors pe c i e s ’g r oups( Sut he r l a nd1996a ;Me nkhor s ta nd
63
Knight 2001), and so vary in their applicability and relative detection success for
64
different taxa. Consequently, the choice of survey method(s) is a critical factor
65
influencing the accuracy and comprehensiveness of survey results.
Wildlife surveys of species occurrence and
66
Several studies have investigated the relative success of different survey methods
67
for detecting mammal and/or reptile species in Australian landscapes including, but
68
not limited to: pit-fall traps with or without drift fences (e.g. Mengak & Guynn 1987;
69
Friend et al. 1989; Laurance 1992; Catling et al. 1997; Crosswhite et al. 1999;
70
Moseby and Read 2001; Ryan et al. 2002), Elliott traps (e.g. Laurance 1992; Catling
71
et al. 1997; Clemann et al. 2005), wire cage traps (e.g. Friend 1978; Laurance 1992;
72
Catling et al. 1997), direct observations and/or active searches (e.g. Brown & Nicholls
73
1993; Catling et al. 1997; Crosswhite et al. 1999; Ryan et al. 2002), hair tubes or
74
funnels (e.g. Catling et al. 1997; Lindenmayer et al. 1999; Mills et al. 2002) and,
75
vocalisations and/or indirect signs such tracks, scats, diggings or scratches (e.g. Friend
76
1978; Catling et al. 1997; Mills et al. 2002). Across all of these studies, the common
77
finding is that different survey methods are useful for sampling particular fauna
78
species and no single approach accurately samples all species within a community.
79
Therefore, as advocated by numerous previous researchers, surveys aimed at detecting
80
multiple species must employ a suitable combination a survey methods (e.g. Laurance
81
1992; Brown and Nicholls 1993; Catling et al. 1997; Crosswhite et al. 1999;
82
Lindenmayer 1999; Ryan et al. 2002; Doan 2003). The selection of these methods
83
should be inf l ue nc e dbyt hes pe c i e sors pe c i e s ’gr oupofi nt e r e s t ,butc ons i de r a t i oni n
84
the survey design must also be given to the dietary and habitat preferences,
85
behavioural attributes and body size of the target species (Mengak and Guynn 1987;
86
Laurance 1992; Catling et al. 1997; Crosswhite et al. 1999; Lindenmayer 1999; Mills
87
et al. 2002).
3
88
In addition to differences in detection success, each wildlife survey method varies
89
in the required degree of effort (person hours) and the cost expended to detect target
90
fauna. Consequently, the choice of survey method is commonly limited by the project
91
financial budget and time frame. It is important, therefore, that the method(s) selected
92
will produce the greatest detection success whilst maintaining low overhead costs.
93
Such information is particularly pertinent for surveys that aim to detect a range of
94
s pe c i e sa nds pe c i e s ’gr oups .Al t houg has ma l lnumbe rofa ut hor sha vequa l i t a t i ve l y
95
discussed effort associated with various survey techniques (e.g. Catling et al. 1997;
96
Crosswhite et al. 1999; Mills et al. 2002), we could not find any studies that explicitly
97
examined and compared quantitative costs associated with various survey methods.
98
This paper compares six survey methods for detecting terrestrial reptile and small
99
mammal species in terms of their relative detection success and costs of surveying.
100
Three key questions were posed: (i) What is the relative success of each method for
101
detecting reptiles and mammals? (ii) What is the cost associated with each method?
102
and, (iii) What is the most successful and cost efficient combination of methods?
103
These questions are addressed using results of wildlife surveys conducted within
104
urban remnant habitat fragments of Brisbane City.
105 106
Methods
107
Study area and survey design
108
The study was conducted within the Brisbane City Council (BCC) Local
109
Gove r nme ntAr e a( LGA)ofs out he a s tQue e ns l a nd( 153º 2’ S,27º E;a r e a1, 220km2,
110
population > 1 million) (Figure 1). A total of 59 survey sites were established within
111
lowland, remnant bus hl a ndf r a g me nt sl oc a t e di nt heCi t y ’ ss out he r n( Ka r a wa t ha )a nd
112
south-e a s t e r n( Bur ba nk)s ubur bs( Fi g ur e1) .Br i s ba nei sAus t r a l i a ’ sf a s t e s tg r owi ng
113
capital city and has already cleared approximately two-thirds of the pre-European
114
woody remnant vegetation for urban development (Brisbane City Council 2001).
115
This extensive loss and fragmentation of native vegetation has impacted on native
116
wildlife assemblages. Having made significant acquisitions of local forest remnants
117
for conservation, BCC has a strong interest in acquiring sound scientific knowledge
118
that will enhance urban planning, management (both on and off reserves), restoration
119
and, biodiversity conservation decision-making processes. In order to achieve this
120
long-term goal of effectively conserving native wildlife assemblages within remnant
4
121
habitat fragments, it is essential that we first know the distribution of species across
122
the urban landscape and how this relates to habitat loss, fragmentation and condition.
123 124
INSERT FIGURE 1 NEAR HERE
125 126
Survey design
127
To reduce variability in vegetation composition, survey sites were located within
128
the Regional Ecosystem (RE) type 12.9-10.4, which is dominated by scribbly gum
129
(Eucalyptus racemosa) woodland located on sedimentary rocks and sandy soils
130
(Young & Dillewaard 1999). Each site measured 20 m x 45 m and was surveyed
131
using three parallel transects 10 m apart, orientated perpendicular to the natural slope
132
of the land. Each site was surveyed using a combination of live-trapping and passive
133
detection methods. Terrestrial reptile and small to medium mammal species (< 3 kg)
134
were surveyed over three consecutive nights during fine weather days in spring and
135
summer. Initial surveys of all sites occurred in 2004. Repeat surveys of 51 sites were
136
conducted in 2005; nine sites were not repeat-surveyed due to recent fire or human
137
interference.
138 139 140
Trapping & detection methods Each site was surveyed using a combination of: 8 wire cage traps, 10 Elliott traps,
141
5 dry pit-fall traps (10 L buckets), and 3 hair funnels.
Traps were spaced
142
approximately 5 m apart along the three transects (Figure 2) and, wherever possible,
143
were positioned to maximise the chances of being encountered by an animal by
144
placing traps alongside, on, or in logs, grass runways or possible shelter sites
145
(Sutherland 1996b; Cunningham et al. 2005).
146
funnels were baited with the standard Australian mammal mixture of peanut butter,
147
rolled oats and honey, with vanilla essence also added (Menkhorst & Knight 2001).
148
In addition, a piece of apple was used as bait in the cage traps and Elliott traps. Pit-
149
fall traps were left unbaited.
150
conducted opportunistically during each site visit.
Cage traps, Elliott traps and hair
Direct observations and scat collection were also
151 152
INSERT FIGURE 2 NEAR HERE
153
5
154
Cage traps were used to detect medium-sized terrestrial mammals such as native
155
rodents (e.g. Rattus fuscipes and Rattus lutreolus) and bandicoots (e.g. Isoodon
156
macrourus and Perameles nasuta), whereas Elliott traps targeted small-bodied species
157
such as dunnarts (Sminthopsis spp.) and antechinus (Antechinus spp.).
158
funnels (Faunatech Pty Ltd, Bairnsdale, Victoria).
159
medium-sized mammals differed in design from other hair sampling devices (e.g.
160
Lindenmayer et al. 1999; Mills et al. 2000; Scotts and Craig 1988) in having only a
161
single large opening that tapers to an enclosed bait chamber. A specialised wafer was
162
attached to the upper inside surface of the funnel. The wafer was covered with a
163
s t i c kys ubs t a nc e( ‘ f a una g oo’ ) ,whi c hr e pl aces the double-sided tape used in previous
164
similar traps to collect hair samples. Dry pit-fall traps were employed primarily to
165
detect small reptile species, with direct observations being used to detect large-bodied
166
reptiles that were unlikely to be detected by other methods. Any scats detected were
167
also collected for ex situ analysis.
The hair
used to detect both small and
168
Cage and Elliott traps were set and baited each afternoon before sunset, checked
169
for captures before dawn the following morning and then closed during the day.
170
Captured animals were identified to species-level using a field guide (Menkhorst &
171
Knight 2001), photographed, weighed, sexed and immediately released at the point of
172
capture. Hair funnels were set and baited at the start of the three day survey cycle and
173
left undisturbed until collection at the end of the survey cycle. All wafers with hair
174
samples were sent for identification ex-situ by one of two independent experts (Initial
175
surveys: Michiala Bowen; Repeat surveys: Barbara Triggs).
176
identified to species level wherever possible, with identifications being classified as
177
e i t he r“ de f i ni t e ”or“ pr oba bl e ” . Onl yde f i ni t es pe c i e si de nt i f i c a t i onswe r eus e df or
178
subsequent data analyses.
Hair samples were
179
Dry pit-fall traps were established at least one week prior to site surveys to allow
180
species and habitat to recover from the localised disturbance that occurs during
181
placement of the traps. Dense vegetation and fallen woody debris at most sites
182
prevented the use of drift-fences that have previously been used in conjunction with
183
pit-fall traps to improve capture success (e.g. Mengak & Guynn 1987; Friend et al.
184
1989; Crosswhite et al. 1999; Menkhorst & Knight 2001). Pit-fall traps were open for
185
the duration of the survey cycle and were checked for captures each morning and
186
afternoon. Captured animals were identified to species-level using a field guide
187
(Wilson 2005), photographed, weighed, sexed (if possible) and immediately released 6
188
at the point of capture. Between the initial and repeat wildlife survey periods, lids
189
were securely fitted to each pit-fall trap to prevent captures. Direct observations and
190
scat collections were used opportunistically throughout all site visits to identify target
191
species. All scats collected were identified ex situ by the same independent experts
192
whoa na l y s e dt heha i rs a mpl e s .Onl yde f i ni t es pe c i e s ’i de nt i f i c a t i onswe r eus e di n
193
subsequent analyses.
194
The relative success of each survey method was determined by evaluating the total
195
number of species detected by each method across all sites. The total number of
196
“ uni que ”s pe c i e sde t e c t e dbye a c hme t hodwa sa l s oe xa mi ne d.Uni ques pe c i e swe r e
197
those species detected by only one survey method (sensu Doa n2003) . Spe c i e s ’
198
detections from the initial and repeat surveys were collated for analyses.
199 200
Cost analysis
201
The cost of each survey method was calculated independently based on the cost
202
output required to survey a single site over one survey cycle (i.e. over 3 consecutive
203
nights).
204
equipment costs, bait/analysis costs, personnel costs and travel costs.
Four main areas of cost expenditure were considered for each method:
205
Equipment costs included expenditures for acquiring traps as well as additional
206
items required to prepare each trap. Trap acquisition costs for each method were
207
calculated at 2004 purchase prices. Additional preparatory expenses included shade
208
cloth for cage traps, hair wafers for hair funnels and, the hire of a motorised auger for
209
digging pit-fall traps.
210
Bait/analysis costs covered bait expenses as well as ex situ hair and scat analysis
211
charges. The cost of bait was calculated based on the cost of bait ingredients per trap
212
over the three night survey cycle. Cage traps and hair funnels used larger peanut
213
butter balls than Elliott traps and the price was adjusted accordingly. For each survey
214
night, fresh bait was used in cage and Elliott traps, whereas the hair funnel bait was
215
left unchanged during the survey cycle. The charge cost for expert analyses of hair
216
and scat samples differed between the two experts and so an average charge was used
217
to calculate costs of hair and scat analyses.
218
Personnel costs were calculated for two people based on The University of
219
Que e ns l a nd’ smi ni mum hour l ywa g ef orac a s ua lr e s e a r c ha s s i s t a ntof$19pe rhour
220
plus 15.5% on-costs (all prices are given in Australian dollars).
221
calculations incorporated the time taken to prepare traps, establish traps at a site, set
Personnel cost
7
222
and check traps each survey day and, remove traps at the end of the survey cycle.
223
Although observation and scat collection were not standardised, an approximate time
224
for each activity per site was calculated.
225
Tr a v e lc os t swe r eba s e donTheEc ol ogyCe nt r e ’ s( TheUni ve r s i t yofQue e ns l a nd)
226
vehicle hire charge of $0.50/km, with an average of 60 km per return trip, per site
227
visit.
228
method and included trips to establish, set, check and, remove traps or conduct direct
229
observations/scat collection.
The number of return trips was calculated independently for each survey
230 231 232
Cost versus success The most effective survey method or combination of methods was based on both
233
s pe c i e s ’de t e c t i ons uc c e s spe rs i t ea ndt r a ppi ngc os tpe rs i t e .Thet ot a lnumbe r sof
234
individuals and species detected per survey method was averaged across sites to give
235
the average numbers of individuals and species detected per method per site. This
236
average detection success plus the average cost of each survey method per site was
237
compared in order to identify the most effective and efficient combination of methods.
238 239
Results
240
Species Detected
241
A total of 28 target native terrestrial reptile and small mammal species,
242
representing 11 family groups, were detected from the 59 sites surveyed (Table 1). A
243
number of non-target species were also detected, including large terrestrial mammals
244
(wallabies and kangaroos), invertebrates, amphibians, birds, arboreal marsupials and
245
exotic mammal and reptile species.
246 247
INSERT TABLE 1 NEAR HERE
248 249
Survey method success
250
Each survey method successfully identified at least two target species, with
251
certain methods detecting up to 14 species (Figure 3a). As expected, each method
252
was mainly suited to detecting either mammals or reptiles, with no method detecting
253
both mammals and reptiles in equal proportions (Figure 3a). Although there was a
254
degree of overlap in the species detected by each survey method, all methods detected
255
at least one species not detected by another method (Figure 3b). 8
256 257
INSERT FIGURE 3 NEAR HERE
258 259
Cage traps
260
A total of 2664 trap nights produced a total of 277 captures (capture success =
261
10.4%). Target reptile and mammal species comprised 6.9% (n=19) of the total cage
262
trap captures. Collectively, these species represented three family groups and four
263
species (Table 1). With the exception of one reptile capture (carpet python, Morelia
264
spilota), all target species captured by this method were medium-sized mammals.
265
The northern brown bandicoot (Isoodon macrourus) was the most commonly captured
266
mammal (n=14 across 7 sites). Bush rats (Rattus fuscipes) were captured on two
267
nights at a single site and the swamp rat (Rattus lutreolus) and carpet python were
268
trapped at one site each, from a single capture. The bush rat, swamp rat and carpet
269
python were not detected by any other survey method (Table 1).
270
Captures of non-target species included: the common brush-tail possum
271
(Trichosurus vulpecular) (n=124), exotic black rat (Rattus rattus) (n=100), introduced
272
cane toad, Bufo marinus (n=26), Australian magpie (Gymnorhina tibicen) (n=6), grey
273
butcherbird (Cracticus torquatus) (n=2) and, Torresian crow (Corvus orru) (n=1).
274
Overall, cage traps were found closed without captures 6.9% of the time (n=184).
275 276
Elliott traps
277
A total of 3330 trap nights produced 55 captures for an overall trap capture
278
success of 1.7%.
Of these captures, 34.5% (n=19) were target species that
279
represented two mammal species from different families (Table 1).
280
dunnarts (Sminthopsis murina) were captured more frequently and across a greater
281
number of sites (n=12 across 7 sites) than yellow-footed antechinus (Antechinus
282
flavipes) (n=7 across 4 sites). Both species were detected only by this method (Table
283
1). Non-target species captured by Elliott traps included: cane toads (n=16), house
284
mouse Mus musculus (n=14), giant white-kneed king cricket (Australostoma
285
australasiae) (n=4), centipede (n=1), and a juvenile common brush-tail possum (n=1).
286
Elliott traps were found closed without captures 4% of the time (n=133).
Common
287 288
Dry pit-fall traps
9
289
Of the 568 pit-fall traps used during the survey periods, 105 were successful in
290
capturing target species (18.5%). A total of 12 reptile species (representing three
291
families) and one mammal species were detected (Table 1). The reptile species
292
captured were small-bodied species or juveniles of larger-bodied species (e.g. juvenile
293
bearded dragon (Pogona barbata)). Four reptile species were not detected by any
294
ot he rme t hod:Ve r r e a ux’ ss ki nk( Anamalopus verreauxii), scute-snouted calyptotis
295
skink (Calyptotis scutirostrum), copper-tailed skink (Ctenotus taeniolatus) and,
296
eastern stone gecko (Diplodactylus vittatus) (Table 1). The only mammal species
297
captured in pit-fall traps was the common planigale (Planigale maculata).
298
species was identified from two captures of individuals at two different sites. The
299
common planigale was detected during surveys only by this method (Table 1).
This
300
Non-t a r g e ts pe c i e s ’c a pt ur e swe r ec ommoni npi t -fall traps, with invertebrate
301
species such as ants, spiders, snails and crickets being the most common by-captures.
302
Non-target vertebrate by-captures were all amphibians: cane toads (n=16), ornate
303
burrowing frogs (Lymnodynastes ornatus) (n=7), and copper-backed broodfrogs
304
(Pseudophryne raveni) (n=5).
305 306
Hair funnels
307
A total of 341 wafers were used during the surveys, of which 84 (24.6%)
308
contained hair samples. Of the 84 wafers with hair samples, 17 (20.2%) contained
309
hair that was able to be definitely identified to the species level, with seven of these
310
representing target species. Three target mammal species were positively identified
311
from hair samples: brown antechinus (Antechinus stuartii), northern brown bandicoot,
312
and long-nosed bandicoot (Perameles nasuta). The brown antechinus and long-nosed
313
bandicoot were identified only by this method (Table 1). Although hair funnels
314
specifically target mammal species, a live reptile by-catch of a single garden skink
315
(Lampropholis delicata) was found on a wafer at one site.
316 317
Direct observations and scat analyses
318
Opportunistic species identifications through direct observations and scat
319
collection and analyses respectively identified a total of 14 target reptile species and
320
two target mammal species (Table 1).
321
species not detected by any other method (Table 1). Of the two mammals detected
322
from scats (Table 1), the Melomys could not be positively identified to species level,
Direct observations identified six reptile
10
323
although the grassland melomys (M. burtoni) was considered probable. As this was
324
the only detection from this genus, the genus record was included in subsequent
325
analyses.
326 327
Cost of detection methods
328
There were significant variations in cost among the survey methods (Figure 4).
329
Total costs to survey a single site over three nights ranged from $178.86 for hair
330
funnels to $925.66 for cage traps. Elliott trapping was the most expensive method
331
($815.18) after cage trapping, despite more Elliott traps than cage traps being used to
332
survey a site (n=12 and n=10, respectively). Pit-fall traps, direct observation, and scat
333
analysis were all similar in cost ($626.37, $655.52, $660.52 per site respectively).
334
The main differences in costs resulted from equipment and travel expenses associated
335
with each method (Figure 4).
336 337
INSERT FIGURE 4 NEAR HERE
338 339
Cost vs. success
340
Overall, it appeared that pit-fall trapping was the most effective and efficient
341
survey method, detecting both the highest number of species (n=0.0018) and captures
342
(n=0.003) per dollar (Figure 5a). Direct observations, followed by hair funnels were
343
the next most successful and efficient survey methods (Figure 5a). Elliott traps and
344
cage traps were roughly similar in their cost per species and cost per capture, yet both
345
were substantially less economic than hair funnels (Figure 5a). Comparatively, scat
346
detection/analysis had the lowest detection success for money spent, with 0.0000941
347
species and captures detected per dollar (Figure 5a).
348
For reptiles, the most successful survey methods mirrored those for overall
349
detection costs. Pit-fall traps produced the highest species detection (n=0.0017) and
350
capture success (n=0.0029) per dollar outlay (Figure 5b).
351
observations were the next most effective and efficient method (Figure 5b), with per
352
dollar values for number of species detected and number of captures equal to those
353
shown in Figure 5a, as mammals were not detected using this method (Figure 3a).
354
The remaining four methods failed to detect reptiles, with the exception of the single,
355
unusual by-catch in a hair funnel and a cage trap.
Similarly, direct
11
356
For mammals, pit-fall trapping and direct observations were the least successful
357
and most costly methods (Figure 5c). Hair funnels were found to produce the greatest
358
number of species detections (n=0.00066) and captures (n=0.00076) per dollar,
359
implying the lowest cost per species detected and per capture (Figure 5c). Elliott traps
360
were the next most cost efficient and successful method, detecting more species
361
(n=0.00025) and captures (n=0.000395) per dollar than cage traps (0.000165 species
362
and 0.00033 captures per dollar) (Figure 5c). Scat detection/analysis produced more
363
species detections and captures (n=0. .0000941) per dollar than pit-fall trapping
364
(n=0.0000541) (Figure 5c).
365
trapping had a higher cost per detection and capture than the other methods, with the
366
exception of direct observations which were not useful for detecting any target
367
mammal species (Figure 5c).
However, both scat detection/analysis and pit-fall
368 369
INSERT FIGURE 5 NEAR HERE
370 371 372
Discussion
373 374
No one survey method independently detected all species recorded during the
375
surveys, yet each method was important for detecting between 1-6 species that were
376
not detected by any other method. There were distinct biases between methods in
377
t e r msoft hes pe c i e s ’g r oup( r e pt i l e sorma mma l s )mos ts uc c e s s f ul l yde t e c t e d.Pi t -fall
378
traps and direct observations were substantially more successful in detecting reptile
379
species, whereas hair funnels, scat detection/analysis, cage traps and Elliott traps were
380
more useful for detecting mammal species. Such detection biases correspond to the
381
purpose for which each method was designed (Sutherland 1996a). However, it also
382
indicates that, as noted by Laurance (1992), the use of only a single method in fauna
383
c ommu ni t ys ur ve y swi l l“ …bebi a s e dt owa r danon-random subset of species in the
384
c ommu ni t y . . . ”( p.654) .The r e f or e ,whe ns ur ve y i ngf a unac ommuni t i e s ,i ti se s s e nt i a l
385
that combination of survey methods are employed in order to adequately sample a
386
range of species. This finding is consistent with previous studies that have also
387
advocated the use of a combination of techniques for surveying a range of wildlife
388
species (e.g. Mengak & Guynn 1987; Laurance 1992; Catling et al. 1997;
389
Lindenmayer et al. 1999). 12
390
We found a considerable difference among methods in terms of the cost outlay
391
required for detecting ground-dwelling mammal and reptile species. However, these
392
calculations were based on the complement of traps used during the study to survey
393
each site and therefore, such costs may vary for other studies depending on the
394
number of each survey method utilised, the duration of active searches and, the
395
analysis of hair/scat samples relative to the success of these methods. To help provide
396
a direct comparison between the success and cost of each survey method, success was
397
i nt e r pr e t e di nt e r msof‘ va l uef o rmone y ’ ;t ha ti s ,t henumbe rofs pe c i e sa ndt he
398
number of captures per dollar spent for each method. Using these calculations, we
399
f oundt ha tt heme t hodsmos ts uc c e s s f ulf orde t e c t i ngva r i ouss pe c i e sa nds pe c i e s ’
400
g r oupswe r ea l s ot hos et ha tpr oduc e dt hemos tnumbe rofma mma la ndr e pt i l es pe c i e s ’
401
detections and captures at the least cost.
402 403
Reptiles
404
Based on the results of this study, the most effective trapping methods for
405
terrestrial reptile surveys are a combination of pit-fall traps and direct observations.
406
Despite being opportunistic rather than standardised, direct observations detected
407
more overall reptile species, as well as more unique species than pit-fall trapping.
408
However, pit-fall trapping was more cost effective than direct observations, detecting
409
more species and captures per dollar. This suggests that pit-fall trapping would
410
produce the highest species detection and capture success for the least amount of
411
money.
412
significantly biased by body size and behaviour. Large-bodied reptiles such as lace
413
monitors, snakes and dragons that were unlikely to be captured in pit-fall traps were
414
detected by direct observation. The exception was a pit-fall trap capture of a single
415
juvenile bearded dragon that was too small to escape from the trap.
However, the unique species detected by each of these methods was
416
Comparatively, the species detected by pit-fall traps were small-bodied, cryptic,
417
nocturnal and/or burying reptiles such as small skinks, eastern stone geckos, and
418
Ve r r e a ux’ ss ki nks .Ther e l a t i ves pe c i e sde t e c t i ons uc c e s sofpi t -fall traps is expected
419
to have been even greater than direct observations if it had been possible to use drift
420
fences and larger traps (buckets). Crosswhite et al. (1999), for instance, showed that
421
more reptiles were captured using pit-fall traps combined with drift-fences than
422
through active searches and Catling et al. (1997) concluded that increasing the size of
423
the buckets used as pit-fall traps would likely have increased the capture success of 13
424
larger-bodied species which were able to otherwise escape. However, increasing the
425
trap size and/or incorporating drift fences would also have increased the cost
426
associated with pit-fall trapping.
427
Similarly, given that all direct observations were opportunistic, it may be
428
expected that a dedicated, time-constrained active search period would have identified
429
additional species. However, in accordance with reports by Crosswhite et al. (1999)
430
and Ryan et al. (2002), pit-fall trapping is still likely to have detected the highest
431
number of species and captures.
432
associated with personnel time and experience is likely to influence the accuracy of
433
active search results, thereby potentially offsetting any increase in species detections
434
through time-constrained searches (Crosswhite et al. 1999; Silveira et al. 2003).
Furthermore, additional costs and limitations
435
Based on the cost efficiency and detection success of pit-fall trapping and direct
436
observations, we recommend that pit-fall trapping be used as the primary technique
437
for surveys of small-bodied terrestrial reptiles. Where habitats and budgets allow,
438
drift fences should also be used to increase capture success (Friend et al. 1989;
439
Moseby and Read 2001). For surveys focussing on larger-bodied reptiles, time-
440
constrained active searches are recommended as the most cost efficient and
441
productive detection method.
442
terrestrial reptile species, a combination of pit-fall traps and active searches are likely
443
to be the best combination of survey methods for detecting the highest number of
444
species and captures per dollar. Furthermore, when used in combination, the travel
445
costs for each survey method were approximately 50% less, which may compensate
446
for increased expenses associated with the inclusion of drift-fences and even increased
447
search times.
However, when attempting to survey a range of
448 449
Mammals
450
Mammal species were detected by five of the six survey methods employed.
451
Optimum trapping methods for terrestrial, small- and medium-sized mammal surveys
452
were hair funnels, followed by Elliott traps and cage traps, as well as scat analysis and
453
pit-fall traps to a lesser degree. Although hair funnels, Elliot traps and cage traps all
454
detected the same number of unique species, the cost effectiveness of these captures
455
varied significantly. Hair funnels were the most economical form of surveying target
456
mammals, detecting more species and captures per dollar than the other mammal
457
survey methods. The relative cost effectiveness of hair funnels is most likely related 14
458
to the advantages this method has over live trapping methods in being less labour-
459
intensive, able to detect more than one species or individual per funnel, and able to
460
capture hair from species of various body-sizes (Lindenmayer et al. 1999; Mills et al.
461
2002). However, unlike live trapping methods, differentiating between individuals of
462
the same species is not possible using hair funnels, thereby limiting the usefulness of
463
t hi sme t hodf ors ur ve y sa i me da tde t e r mi ni ngs pe c i e s ’a bunda nc e . Fur t he r mor e ,
464
accurately identifying hair samples to the species level is a difficult process that is
465
susceptible to hair samples being incorrectly identified or not able to be identified at
466
all. Lobert et al. (2001), for instance, tested the accuracy of hair identification by two
467
independent experts and found that almost half of the samples analysed involved
468
some degree of identification error. Furthermore, the identification of dog hair from a
469
hair funnel used in Lindenmayer et al. ’ s( 1999)s t udywa sque s t i ona bl eg i ve nt heha i r
470
sample was from an arboreal funnel (see also Kavanagh & Stanton 1998). However,
471
the positive species identifications from hair samples collected during this study are
472
reasonable and were considered to be accurate.
473
There were also clear associations between the body size of mammals and the
474
success of various methods for detecting different species. Elliott traps, given their
475
size, detected only small-bodied mammal species, with the exception of a single by-
476
catch of a juvenile brush-tail possum at one site. Similarly, small-bodied species,
477
such as dunnarts and antechinus were not captured in cage traps probably due to the
478
lower sensitivity of cage trap treddles and the light weight of small-bodied species.
479
Cage traps were, however, successful in capturing medium-sized species such as
480
rodents and bandicoots, whose body size prevented captures in Elliott traps. Due to
481
their tapered design and large surface area for capturing hair samples, hair funnels
482
detected both medium- and small-bodied terrestrial mammals, including species not
483
captured by live trapping methods (e.g. long-nosed bandicoot and brown antechinus).
484
Furthermore, although more commonly used for reptile surveys, pit-fall trapping
485
was the only method to detect the occurrence of planigales during this study. This is
486
consistent with previous studies that have found pit-fall traps to be useful for detecting
487
small, elusive mammal species that rarely enter other traps (e.g. Milledge 1991,
488
Laurance 1992, Catling et al. 1997, Menkhorst & Knight 2001). Therefore, unless a
489
project is specifically targeting planigales (or similar elusive, shy species), or has a
490
sufficiently large budget, pit-fall traps are not recommended for mammal surveys.
491
Scat detection and analysis also identified one small mammal (Melomys spp.) not 15
492
detected by any other method. However, these scat samples were not able to be
493
positively identified to the species level, suffering the same analysis difficulties as
494
hair sample identifications. Based on our results, both pit-fall trapping and scat
495
detection/analysis methods would require a substantial cost outlay in order to detect as
496
many species and captures as the other methods.
497
recommended as supportive methods only if the project budget allows. Alternatively,
498
excess funding could be allocated to increasing the survey-intensity of optimal survey
499
methods or, by exploring the use of additional bait types, such as meat products, to
500
help improve the range of species detected (e.g. herbivores as well as omnivores and
501
carnivores) (Laurance 1992; Mills et al. 2002).
As such, these methods are
502
Therefore, based on the results from this study, we propose that optimal survey
503
methods for detecting medium-bodied terrestrial mammals are a combination of cage
504
traps and hair funnels. Comparatively, small-bodied terrestrial mammals are best
505
surveyed using Elliott traps and hair funnels. Complementary pit-fall traps should
506
also be used if attempting to detect planigales or similarly elusive mammal species.
507
However, if only planigales or similar species are being targeted, then intensive pit-
508
fall trapping should be adopted as the primary survey method. Like reptile surveys,
509
drift fences may be adopted to increase capture success (e.g. Mengak and Guynn
510
1987).
511
successful than found in this study, although it is best used as a supplementary
512
method with other techniques only if funds permit.
In habitats with sparse ground cover, scat detection may prove more
513 514 515
Acknowledgements
516
This research formed part of a collaborative project between The University of
517
Queensland and Brisbane City Council. Fauna surveys were conducted under UQ
518
AEC permits, GSP/030/04/BCC/UQGS, and a Queensland Government EPA
519
scientific purposes permit, WISP01975204. Financial support was provided to JG by
520
Brisbane City Council and a UQ graduate scholarship. We also wish to acknowledge
521
the support of private land-owne r sa ndRe dl a ndShi r eCounc i l ’ sWa t e ra ndWa s t e
522
Division in allowing access to their properties.
523
volunteers who assisted with digging holes for pit-fall traps, Michiala Bowen and
524
Barbara Triggs for analysing hair and scat sampl e sa nd,t ot hepr oj e c t ’ sr e s e a r c h
Thanks also to: the numerous
16
525
assistants, Michelle Walton and Alison Howes, for dedicated support and assistance
526
during field surveys.
527 528
References
529
Brown, G. W., Nicholls, A. O. (1993). Comparative census techniques and modelling
530
of habitat utilizat i onbyr e pt i l e si nnor t he r nVi c t or i a .I n‘ He r pe t ol ogyi nAus t r a l i a :a
531
Di ve r s eDi s c i pl i ne ’ .( Ed.D.Lunne ya ndD.Ay e r s . )pp.283-290. (Royal Zoological
532
Society of New South Wales: Mosman.)
533 534
Brisbane City Council. (2001). State of the Environment Report: Brisbane 2001.
535
Brisbane City Council. (Brisbane City Council: Brisbane.)
536 537
Catling, P. C., Burt, R. J., Kooyman, R. (1997). A comparison of techniques used in a
538
survey of the ground-dwelling and arboreal mammals in forests in north-eastern New
539
South Wales. Wildlife Research 24, 417-432.
540 541
Clemann, N., Long, K., Skurrie, D., and Dzuris, J. (2005). A trapping survey of small,
542
ground-dwelling vertebrates in the Little Desert National Park, Victoria. Australian
543
Zoologist 33, 119-126.
544 545
Crosswhite, D. L., Fox, S. F., Thill, R. E. (1999). Comparison of methods for
546
monitoring reptiles and amphibians in upland forests of Ouachita Mountains.
547
Proceedings of the Oklahoma Academy of Science 79, 45-50.
548 549
Cunningham, R. B., Lindenmayer, D. B., MacGregor, C., Barry, S., and Wlesh, A.
550
(2005). Effects of trap position, trap history, microhabitat and season on capture
551
probabilities of small mammals in a wet eucalypt forest. Wildlife Research 32, 657-
552
671.
553 554
Doan, T. M. (2003). Which methods are most effective for surveying rainforest
555
herpetofauna? Journal of Herpetology 37, 72-81.
556
17
557
Friend, G. R. (1978). A comparison of predator scat analysis with conventional
558
techniques in a mammal survey of contrasting habitats in Gippsland, Victoria.
559
Australian Wildlife Research 5, 75-83.
560 561
Friend, G. R., Smith, G. T., Mitchell, D. S., and Dickman, C. R. (1989). Influence of
562
pitfall and drift fence design on capture rates of small vertebrates in semi-arid habitats
563
of Western Australia. Australian Wildlife Research 16, 1-10.
564 565
Kavanagh, R. P., and Stanton, M. A. (1998). Nocturnal birds and arboreal marsupials
566
of the southwestern slopes, New South Wales. Australian Zoologist 30, 449-466.
567 568
Laurance, W. F. (1992). Abundance estimates of small mammals in Australian
569
tropical rainforest: a comparison of four trapping methods. Wildlife Research 19, 651-
570
655.
571 572
Lindenmayer, D. B., Incoll, R. D., Cunningham, R. B., Pope, M. L., Donnelley, C. F.,
573
MacGregor, C. I., Tribolet, C., and Triggs, B. E. (1999). Comparison of hairtube types
574
for the detection of mammals. Wildlife Research 26, 745-753.
575 576
Lobert, B., Lumsden, L., Brunner, H., and Triggs, B. (2001). An assessment of the
577
accuracy and reliability of hair identification of south-east Australian mammals.
578
Wildlife Research 28, 637-641.
579 580
Mengak, M. T., Guynn, Jr. D. C. (1987). Pitfalls and snap traps for sampling small
581
mammals and herpetofauna. American Midlands Naturalist 118, 284-288.
582 583
Me nkhor s t ,P. ,a ndKni g ht ,F.( Eds . )( 2001) .‘ A Fi e l dGui det ot heMa mma l sof
584
Aus t r a l i a . ’( Oxf or dUni ve r s i t yPr e s s :Me l bour ne . )
585 586
Milledge, D. (1991). A survey of the terrestrial vertebrates of coastal Byron Shire.
587
Australian Zoologist 27, 66-90.
588 589
Mills, D. J., Harris, B., Claridge, A. W., and Barry, S. C. (2002). Efficacy of hair-
590
sampling techniques for the detection of medium-sized terrestrial mammals. I. A 18
591
comparison between hair-funnels, hair-tubes and indirect signs. Wildlife Research 29,
592
379-387.
593 594
Moseby, K. E., and Read, J. L. (2001). Factors affecting pitfall capture rates of small
595
ground vertebrates in arid South Australia. II. Optimum pitfall trapping effort.
596
Wildlife Research 28, 61-71.
597 598
Ryan, T. J., Philippi, T., Leiden, Y. A., Dorcas, M. E., Wingley, T. B., and Gibbons,
599
J. W. (2002). Monitoring herpetofauna in a managed forest landscape: effects of
600
habitat types and census techniques. Forest Ecology and Management 167, 83-90.
601 602
Scotts, D. J., and Craig, S. A. (1988). Improved hair-sampling tube for the detection
603
of small mammals. Australian Wildlife Research 15, 469-472.
604 605
Silveira, L., Jácomo, A. T. A., Diniz-Filho, J. A. F. (2003). Camera trap, line transect
606
census and track surveys: a comparative evaluation. Biological Conservation 114,
607
351-355.
608 609
Sut he r l a nd,W.J .( Ed. )( 1996a ) .‘ Ec ol og i c a lCe ns usTe c hni que s :aHa ndbook. ’
610
(Cambridge University Press: Cambridge.)
611 612
Sutherland, W.J .( 1996b) .Ma mma l s . I n‘ Ec ol og i c a lCe ns us Te c hni que s :a
613
Ha ndbo o k. ’( Ed.W.J .Sut he r l a nd. )pp.260-280. (Cambridge University Press:
614
Cambridge.)
615 616
Wi l s on,S.( Ed. )( 2005) .‘ A Fi e l dGui det oRe pt i l e sofQue e ns l a nd. ’( Ne w Hol l a nd
617
Publishers Pty. Ltd.: Sydney.)
618 619
Young ,P.A.R. ,a ndDi l l e wa a r d,H.A.( 1999) .Sout he a s tQue e ns l a nd.I n‘ The
620
Cons e r va t i onSt a t usofQue e ns l a nd’ sBi or e g i ona lEc os y s t e ms ’( Eds .P.S.Sa t t l e ra nd
621
R. D. Williams.) pp. 12/1-12/48. (Environmental Protection Agency: Brisbane.)
622 623 624 19
625 626 627 628 629 630 631 632
Figure 1. Map of study area showing location of (a) Brisbane and central business
633
district (CBD), and site locations within (b) Karawatha area and (c) Burbank area.
634
GIS data provided by Brisbane City Council.
635 636
Figure 2. Site schematic showing trap layout along the three transects.
637
Hair funnels;
Elliott traps;
Cage traps;
Pit-fall traps.
638 639
Figure 3. (a) The total number of species detected by each survey method, and (b)
640
the number of unique species detected by each survey method.
641
Mammals.
Reptiles;
642 643
Figure 4. Relative cost of each survey method in isolation as used during this project
644
to survey one site over a three night period. Total cost for each method comprised
645
expenses relating to:
equipment,
bait/analysis,
personnel time and,
travel.
646 647
Figure 5. Average success of each survey method per site, per dollar. For clarity, the
648
cost of success is shown as success per thousand dollars for: (a) all target species
649
detected; (b) reptiles detected; and (c) mammals detected. For all graphs:
650
number of species per site per thousand dollars;
651
per thousand dollars.
average
average number of captures per site
652 653 654 655 656 657 658 20
659 660 661 662 663 664 665 666 667
Table 1. Collated species list and method/s by which they were detected.
668
Species that were detected by only a single survey method; ●s pe c i e sde t e c t e dby
669
more than one survey method.
670 Family Group Dasyuridae
Native Mammals
Muridae
Peramelidae Agamidae
Native Reptiles
Colubridae Elapidae Gekkonidae Pygopodidae Pythonidae Scincidae
Varanidae
Scientific Name Antechinus flavipes Antechinus stuartii Planigale maculata Sminthopsis murina Melomys sp. Rattus fuscipes Rattus lutreolus Isoodon macrourus Perameles nasuta Diporiphora australis Physignathus lesuerii Pogona barbata Dendrelaphis punctulata Pseudechis porphyriachus Diplodactylus vittatus Lialis burtonis Morelia spilota Anamalopus verreauxii Calyptotis scutirostrum Carlia foliorum Carlia pectoralis Carlia vivax Cryptoblepharus virgatus Ctenotus taeniolatus Eulamprus quoyii Lampropholis amicula Lampropholis delicata Varanus varius
Common Name Yellow-footed antechinus Brown antechinus Common planigale Common dunnart Likely: Grassland melomys Bush rat Swamp rat Northern brown bandicoot Long-nosed bandicoot Tommy round-head Eastern water dragon Bearded dragon Common tree snake Red-bellied black snake Eastern stone gecko Buton's snake-lizard Carpet python Verreaux's skink Scute-snouted calyptotis skink Tree-base litter-skink Open-litter rainbow skink Storr's rainbow skink Fence skink Copper-tailed skink Eastern water skink Secretive skink Garden skink Lace monitor
CT
Survey Method ET PF HF Obs
S
●
● ●
● ● ●
●
● ● ● ● ● ●
671 672
21
● ● ● ●
●
● ●
673
22
674
Figure 1.
675 676 677 678
Main roads
679
Brisbane CBD
680
Remnant Vegetation (1999)
681
Brisbane river & Ocean
682
Survey sites
683
c.
684 a.
685
b.
686 687 688 689 690 691 692 693
b.
c.
694
23
695 696
Figure 2.
697 698 699 700
5m
701 702 703 704
10 m
24
709
Figure 3b.
14
12
10
8
6
4
2
0 Hair funnel
Pit-fall trap
Elliott trap
Cage trap
Scat
708
Scat
706 707 Observation
Survey Method
Observation
Hair funnel
Pit-fall trap
710
Elliott trap
Cage trap
No. Unique Species
Total No. Species
705 Figure 3a. 14
12
10
8
6
4
2
0
Survey Method
711 712
713
714
25
715 716 717
Figure 4. 1,000
Cost ($)
900 800 700 600 500 400 300 200
Scat
Obs
Hair funnel
Pitfall trap
Elliott trap
Cage trap
100 0
Survey Method
718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736
26
742
Figure 5b.
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0 Hair funnel
Pitfall trap
Scat
741
Scat
739 740 Observation
Survey Method
Observation
Hair funnel
Pitfall trap
743 Elliot trap
Cage trap
Av Species / $1000
738
Elliot trap
Cage trap
Av. Reptile Spp / $1000
737
Figure 5a. 3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
Survey Method
744 745
746
27
Scat
Observation
Hair funnel
Pitfall trap
Elliot trap
Cage trap
Av. Mammal Spp / $1000
747 Figure 5c. 0.8 0.7
0.6
0.5
0.4 0.3
0.2
0.1
0
Survey Method
748 749
750
751
752
753
28
