Biological Sciences, Santa Barbara City College pipeline center for sustainability

Biology 130: Methods in Field Biology

Field Technique:  Track Stations and Camera Traps



(Full paper can be found here)

Medium & Large Mammals: For medium and large mammals, trackplates and camera surveys will be the primary method of detection.

Visual encounters for medium and large mammals, such as additional tracks, scat, foraging marks, or the actual animal, should also be noted on the data sheets along with the location. 

Track Plates:

The track plate covers are made from wooden boxes.  The final dimensions of most of the track plates are 70 cm long x 30 cm wide x 30 cm tall.  The bottom tray is made of a piece of aluminum flashing that is 70 cm long x 29.5 cm wide.  The track plate can be attached to the bottom of the box using Velcro (Drennan et al. 1998) and the contact paper can be attached to the bottom plate using poster putty or tape.  The front & back of the box are unobstructed.  The top piece should be longer to allow each opening to have a 15 cm “overhang” to prevent rain splatter.   

Plates are covered with a carbon black (same as newspaper ink; from a Xerox machine) mix on felt pads and CONTACT paper (sticky side up) which is used to record the tracks (Manley et al. 2004, MELP 1998) as illustrated in the diagram below:  

Side view of a trackplate box.

Track Plate Box side view

Track plate for bottom of box. 

 

Track Plate bottom of box

There are several ways to coat the track plate.  For this project, a felt pad covered with Xerox carbon black (mixed 1 to 1 with paraffin oil or mineral oil) can be attached to the track plate (Weiwel thesis 2003).  Alternatively, a mix of 1 part newspaper ink (Xerox carbon black) and 1 part mineral spirits (or paraffin oil) can be applied to the plate using a roller brush (Lord et al. 1970) or that area could be sprayed with a mixture of 1 part blue carpenter’s chalk mixed with 2 parts alcohol (Drennan et al. 1998).  Plates should be baited with cat food, scent, or some other appropriate attractant.  Old bait is packed out and the track plate is changed if tracks are detected or plate has been damaged by rain.  A large feather could be hung approximately 1.5 meters above the trap, perhaps on a pole, to act as a visual cue (Manley et al. 2004).  The contact paper is covered with clear tape before being removed from the plate bottom and stored with the data sheet.  

Another version of Track plate and cubby construction.

Zielinski (1995) describes three devices for recording the tracks of animals. Two of the devices are covered, sooted aluminum plates with a piece of contact paper (paper with a tacky adhesive on one side) placed sticky side up. When animals walk on the sooted surface, their feet pick up soot that is deposited on the contact paper, leaving a clear black image on a white background.

The alternative is an unenclosed sooted track-plate. This device does not use contact paper to record the tracks; instead the image is created when the animal walking on the plate removes soot. This device is completely open to the weather.

It is suggested that the sooted track-plate enclosed in a wooden cubby is the best all-round design. Fowler and Golightly (1994) recorded many species using this type of track-plate, including martens, ermine, and long-tailed weasels.

The sooted aluminum plates can be protected by stiff plastic sheets formed into a half-cylinder dome or by "cubbies" made from the most economical grade of exterior plywood. The wooden cubbies, although heavier than the plastic domes, better protect the track-plates and are sturdier, allowing limbs and other debris to be placed on them for camouflage. Images can also be obtained from the sooted plates using clear tape, which is then transferred to a sheet of plain white paper.

Plywood cubbies

Construct the plywood cubbies to house the track plate of 1.3 cm (0.5 in) standard- or cull-grade exterior plywood, with interior dimensions of 20x20x80 cm (8x8x32 in).

Cut grooves 1.6 cm (0.63 in) wide and 0.8 cm (0.32 in) deep in the tops and bottoms (25x80 cm; 10x32 inches). The edge of the side pieces (20x80 cm) (8x32 in) will easily fit into the grooves.

The cubbies can be held together with rope, "rubber bands" cut from tire inner tubes, or other devices. 3.75 units can be constructed from one sheet of plywood (120x240 cm; 4x8 ft).

 

Track Plate Box

 

Track Plates using soot or chalk

Construct track plates of 0.063 gauge aluminum sheeting, 20x75 cm (8x30 in).

The plates should be sooted in a well-ventilated area using an acetylene torch with its oxygen valve blocked with tape. Alternatively, a smoky kerosene torch can be used.

To transport the plates, it is necessary to construct a carrying box from 13 mm (0.5 in) plywood. The box should be constructed with a number of slots that can accommodate the sooted plates so that they are not touching.

Contact paper (Rubbermaid Inc.,) cut to 11.5x30 cm (4.6x12 in) should be attached to the centre third of the track plate, with the sticky side up. Do not remove the protective covering until the plate is to be put in place in the field. Use duct tape to hold the contact paper on the sooted plate.

A slight deviation from the above is to use a mixture of alcohol and chalk sprayed on a metal sheet.

 

Track Plate CA Groundsquirrel
(A metal track plate covered in a thin film of blue chalk. Prints from a California groundsquirrel are visible with a knife for size comparison. Photo by Adam Green)

 

It is also possible to make use of existing substrate. Mud and wet sand can be very good for showing tracks. This can be used opportunistically when travelling through and area by checking along trail edges and stream and pond banks.

 

You can also use mud and sand to create a tracking station. By brining water into the field you can level an area and cover with wet mud or sand. Often by placing bait or a plastic disc in the center you can attract animals to investigate and step into the area leaving a print.

Camera Traps:

Here is a good video showing the basics of camera traps and how to place them appropriately:

 

 

biologists caught in camera trap
(Intrepid biologists caught in the act of setting up a camera trap..."yup, it works")

 

Setting up the camera is not as simple as just pointing it in the right dorection. It is difficult to determine if it is set to point at a spot that would capture an animal that passes by.

 

islad fox ear

In the above image you can see at the far right, that we caught an island fox with the camera, but because the camera was pointed too high we can barely see that it is a fox and would not be able to differentiate an individual.

 

mt lion
(Mountain Lion, Big Creek interpretive loop trail- 4/18/15)

 

In this image you can see that the camera is pointed at a good spot on a trail that allows it to pick up movement and take the photo while the animal is still in the frame. Big Creek interpretive loop trail- 4/18/15

 

mt lion

mt lion

mt lion

mt lion
(Mountain Lion, Big Creek interpretive loop trail- 4/17/15)

 

The above camera set was at the edge of a forest and grassland where a trail makes a sharp cut back. The panorama camera can catch both the sections of trail. This type of set in this location allows us to see more of the animal and even get a good profile shot showing a badly emaciated Mountain lion- note the protruding vertebrae from the spine, the thin neck, and the protruding hip bones. It is difficult to determine if the cat in the single frame image is the same as in the panaorama images (2 consecutive nights). The cat in the single image seems to be in better condition, but the image quality is not as good as the panorama shots. There seems to be a nick in the right ear of the cat in the panorama images, but it is too hard to see that level of detail in the single image to make any conclusions.

Cameras can be attached to a tree.  If no suitable trees are found, then cameras (and bait if used) can be attached to stakes.  Stakes MUST be able to withstand weather and animal activity. We can also use tripods to station cameras, but when setting out many cameras it becomes prohibitive to carry enough tripods for all of them.

An additional attractant could be used for both the track plate and camera stations.  This attractant is a mixture of skunk gland derivative (Gusto, Minnesota Trapline Products, Pennock, MN) and lanolin (M&M Fur, Inc, Bridgewater, SD).  A 1 oz jar of Gusto is added to 32 oz of heated lanolin in liquid form.  One tablespoon of the mixture is placed approximately 4 meters from each station on something such as a tree branch.  The mixture is neither re-applied nor removed for the duration of the 10 days.  Alternatively, a commercial scent can be purchased.   

HABITAT AND PLANT SPECIES COMPOSITION DATA COLLECTION:

Environmental variables such as air temperature, wind speed, and other weather conditions should be recorded at the time of the survey on the faunal monitoring data sheet.  A habitat data collection plot should be established at every bird point count location which is the same as the end of every transect for small mammal traps. 

Track Plate & Camera Array Augmentation.

  1. Camera locations- Some species, such as bobcats or coyotes, are believed to avoid bait stations.  For these animals, it may be best to place camera locations along travel routes.

  2. Sampling intensity- If needed, the number of stations could be increased or the sampling duration could be extended.

  3. Polyethylene enclosures- In areas with heavy precipitation, the track plates boxes should be covered with polyethylene. 

  4. Open track plates- For species that are less likely to enter the enclosed track plates or are too large to enter the enclosures.  Open track plates consist of 1 square meter of metal, covered with soot, with the bait placed in the middle.  These are less effective due to rain, fog, and other weather which can wet the tracks.  Alternatively, to attract larger animals, such as coyotes, a patch of ground could be bared, tilled, wetted to create mud, and a white disk (not bait) placed in the center to serve as an attractant.  The site would still be visited every other day and a cast of the tracks would be made using plaster.  This bare-earth method, with a scent tablet for bait, has also been used for raccoons (Smith et al. 1994).

 

The following is excerpted from a paper that compared track stations and camera traps for detecting different mammal species.

Abstract

Activities involving fauna monitoring are usually limited by the lack of resources; therefore, the choice of a proper and efficient methodology is fundamental to maximize the cost–benefit ratio. Both direct and indirect methods can be used to survey mammals, but the latter are preferred due to the difficulty to come in sight of and/or to capture the individuals, besides being cheaper. We compared the performance of two methods to survey medium and large-sized mammal: track plot recording and camera trapping, and their costs were assessed. At Jataí Ecological Station (S21°31'15"–W47°34'42"-Brazil) we installed ten camera traps along a dirt road directly in front of ten track plots, and monitored them for 10 days. We cleaned the plots, adjusted the cameras, and noted down the recorded species daily. Records taken by both methods showed they sample the local richness in different ways (Wilcoxon, T= 231; p;;0.01). The track plot method performed better on registering individuals whereas camera trapping provided records which permitted more accurate species identification. The type of infra-red sensor camera used showed a strong bias towards individual body mass (R2=0.70; p= 0.017), and the variable expenses of this method in a 10day survey were estimated about 2.04 times higher compared to track plot method; however, in a long run camera trapping becomes cheaper than track plot recording. Concluding, track plot recording is good enough for quick surveys under a limited budget, and camera trapping is best for precise species identification and the investigation of species details, performing better for large animals. When used together, these methods can be complementary.

Discussion:

Some advantages and inconveniences could be perceived in both methods. The track plot method showed better detection efficiency, 1.65 times higher than that of camera trapping. However, species identification in track plots is strongly dependent on the researcher’s ability to identify the recorded footprints. For that reason, the researcher himself is required in the field most of the time, instead of a field assistant. Ground characteristics may occasionally bewilder the researcher concerning the animal size, since the same animal footprint gets larger in softer grounds (Stander 1998); in addition, hard and dry substrata are not adequate to record footprints. In this study, some days the soil was so dry that we could not securely identify footprints usually easily identifiable, as of Puma concolor. The track plot method efficiency also depends on weather conditions during the sampling period, since a strong rain or wind can eliminate some records. If the footprint stays in the dry soil for several hours, the wind carries the soil particles away and the footprint begins to fade. It is also challenging even for a skilled person to identify species whose footprints are very similar, as some deer (Mazama americana and Mazama guazoubira) for example. Still, such a method demands long time in the field, as the plots have to be frequently checked and cleaned.

The camera trap method, even though showing lower detection efficiency, certainly provides more accurate records as once photographed the mammal can be easily identified to species level. For some species, especially those having spotted skin, it may be possible to identify individuals (Rudran et al. 1996) that can be very useful when working on capture-mark-recapture of animals; if the marker is well visible (e.g., bright colors in the body or earrings) it will show in the photograph and the photo itself may function as a recapture, saving costs and lowering the risk of wounding and stressing both the animal and the researcher (Tomas and Miranda 2003), and may allow the estimation of population density (Trolle et al. 2007). In some situations, the reproductive condition of the animal can also be recognized in the photos (Srbek-Araújo and Chiarello 2005). Besides, the camera trap method offers conditions to analyze activity patterns of the photographed species, since it is possible to record the time when each photo is taken. Time recording also permits to assess the presence of different individuals of the same species at different times in the same day, while records in track plots do not allow such a differentiation, as footprints of the same species in the same plot and in the same day are reckoned as only one register.

Another advantage of camera trapping is that the researcher is not required to monitor the equipment constantly, as the cameras can be left unaided in the field for several days and any trained person is able to change camera films (if not digital cameras) and batteries. In another study in the same region (Lyra-Jorge et al. 2008) we verified that it was necessary to change 36-picture films only once a month, and the researcher was required in the field only to install the cameras (1 day) plus an additional period to analyze the photos taken.

On the other hand, detection by camera traps showed a strong dependency on the animal body mass, performing in favor of large species. Such a tendency has also been reported by other researchers, since the earliest infra-red camera traps (Wemmer et al. 1996) to the more recent ones (Carbone et al. 2002; Silveira et al. 2003). Other potential failures for infra-red camera traps can be pointed. The cameras used in this study take about one second between the animal detection by the sensor and the triggering, and in some cases the animal can run away before being photographed. This is a possible reason for lower detection rates of the camera traps compared to the track plot method. Also, as the sensor detects motion and changes in temperature, the camera performance reduces in hot days, when the environmental temperature becomes close to the animal body temperature. This is also a reason for higher detection at night, when the contrast between the animal body and the environment temperature is higher (SrbekAraújo and Chiarello 2005). Higher detection at night was also noticed in this study, what can be in part due to that condition and in part because most of the animals detected here have nocturnal habit (Emmons 1997; Reis 2006; G. Ciocheti unpublished data).

Still related to the camera temperature-detection system was the initial difficulty in calibrating the infra-red sensor under hot weather conditions, as it would trigger with temperature oscillation. This problem was much easier to overcome with the national Trapa-camera than with the imported make (Stealth Cam MC2-GV, 35 mm), as the national camera trap was adjusted for tropical conditions. Its sealing system was also more effective, therefore humidity and excess heat did not damage the mechanism.

Camera avoidance behavior in mammals has been noticed, especially in long term studies in which the cameras remain in the same sites, as the animals “remember” the camera presence and avoid the flash. This may be the reason for a higher detection rate at the beginning of long term studies (Wemmer et al. 1996; York et al.2001; Wegge et al. 2004; Jackson et al. 2006). In an 18-month sampling study we also noticed camera shyness (Lyra-Jorge et al. 2008) but not in the present short-time sampling study.

Despite the cost of camera trapping being high at first sight, this method produces permanent records and the cameras can be re-used in other projects. In a medium/long run project, per-day cost of this method lessens with time because the equipment can stay unaided in the field for up to a month, saving travel and personnel expenses. On the other hand, track plot recording method requires daily field visits. Comparing a 10-day with a 30-day survey, camera trapping per-day costs decreased from US$ 305.13 to US$ 101.71 whereas per-day cost of the track plot method remained almost the same (US$ 149.90 against US$ 145.89). If using digital cameras, the cost would be even lower because films (and films development) would not be necessary. Most researchers who evaluate costs and benefits of mammal recording methods agree that more expensive methods, if more accurate, are the best for long term studies and/or when different research groups share field equipment, and that the combination of two or more methods always result in better quality data, especially when surveying rare or secretive species (Stander 1998; Silveira et al. 2003; Sadlier et al. 2004; Gaidet-Drapier et al. 2006; Barea-Azeón et al. 2007; Scheibe et al. 2008).

Considering the benefits and shortcomings of both methods in relation to performance and costs we can conclude that the track plot method is satisfactory when the purpose is to assess local species richness through quick surveys and under a limited budget. Camera trapping, although being more expensive and biased towards larger animals permits precise species identification, the investigation of species activity patterns, and sometimes, the estimation of population density (through individualized records) (Voss and Emmons 1996; Srbek-Araújo and Chiarello 2005); it is an efficient method especially to record vagile animals which are solitary, in low density or live in small groups (Carbone et al. 2001). Both methods can be used together, enhancing field data quality and providing complementary results.

More papers on camera traps:


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Revised 26 January, 2015
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