The theory of the fall factor and two different tree climbing scenarios involving (A) a safe versus (B) an extremely dangerous condition. Note that the fall factor theory applies to ascents when (and only when) the tree climber is located above the last anchor. The black line represents the climbing rope, the arrow: the attachment of the researcher to the rope, the hand: one end of the rope attached to a solid trunk on the ground (the belay), the upper black-and-white circle: the last anchor which would support a fall, and the lower circle: an additional anchor, should the upper one fail because of the shock provided by a fall. The length of rope absorbing the fall is the amount of rope between the climber and the next knot. Assuming the amount of rope between the last anchor and the belay is 15 m in both scenarios, the length of rope that would absorb a fall in Condition A is 18 m (3 m of rope between the researcher and the last anchor, plus 15 m between the last anchor and the belay). However, the climber in Condition B has made a knot with the climbing rope at the last anchor before moving above it, dangerously shortening the amount of rope which could absorb the energy of a fall (3 m).

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Tree Climbing Strategies for Primate Ecological Studies

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Feb 2004

Primate ecological studies can benefit from accessing the canopy to estimate intra-tree and inter-tree variation in food availability and nutrient value, patch and subpatch depletion, foraging efficiency, as well as nest structure and nesting behaviors, parasitic transmission and predator detectability. We compare several ways to access the canopy...

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... II. Variation in the fall factor of 28 individual trees climbed during a 1-yr primate field study. Trees divided as main canopy tree (m) versus emergent tree (e) to compare which of the 2 categories presents a higher climbing risk. Height and length in m Length of rope Climber’s height Length of which would have Fall Tree species above last anchor potential fall absorbed the fall factor (m) 10 20 22 0.91 (m) 5 10 19 0.53 (m) 5 10 24 0.42 (m) 6 12 21 0.57 (m) 4 8 25 0.32 (m) 7 14 26 0.54 (m) 7 14 25 0.56 (m) 6 12 26 0.46 (e) 6 12 30 0.40 (e) 9 18 25 0.72 (e) 2 4 26 0.15 (e) 4 8 28 0.29 (e) 4.5 9 31 0.29 (e) 6 12 35 0.34 (e) 6 12 25 0.48 (e) 4.5 9 34 0.26 (e) 2.5 5 26 0.19 (e) 11.5 23 32 0.72 (e) 7 14 29 0.48 (e) 4.5 9 31 0.29 (e) 5 10 30 0.33 (e) 4 8 30 0.27 (e) 6 12 30 0.40 (e) 6 12 29 0.41 (e) 3 6 24 0.25 (m) 4 8 30 0.27 (e) 1 2 21.5 0.09 (m) 1.5 3 16 0.19 Mean 5.3 10.6 26.8 0.40 Note. Fall factors calculated as length of potential fall divided by length of rope which would have absorbed the fall (Fig. 2). No knot has been tied at the last anchor (equivalent of Figure 2, condition A). Climber’s height above last anchor was measured with a 50-m tape. The use of a second independent safety device (like a daisy chain, Fig. 1e and text) has not been considered in calculations because there is the real possibility for a climber to fall before the additional safety device could be properly installed. All trees located in Kanyawara (Kibale N.P., Uganda), UTM: N36, 2 km of radius from 0.56567 North 30.35684 ...

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... the Single Rope Technique, though one might compensate by rappelling rather than climbing down with the spurs. If the same tree must be climbed many times, this method is not recommended as it may have long-term effect on tree survival. To determine how much damage could be done to trees accessed with the climbing spurs, we noted whether spur holes were later infested by insects, losing sap, par- asitized by mushrooms, or whether bark formed again and recovered the original hole. For the 26 species of trees monitored, 20 exhibited no sign of insect or mushroom invasion and were not bleeding. Since local employment is a critical issue for conservation, we recommend that primate researchers hire local climbers who master the use of spurs to climb trees (contra Moffett and Lowman, 1995) but only on those trees that are known not to be spur- sensitive. How dangerous is tree climbing? For the Single Rope Technique, one way to answer this question is to consider whether the tree climber is located above or below the last anchor. An anchor is a support over which the climbing rope is free to move, like a branch in a tree. The last anchor is the highest point of support over which the rope has been passed. When the climber is located below the last anchor, the risk of falling is practically nil because there is no slack in the rope: the latter is attached on the ground at the belay, goes up until it passes over the branch and comes back down to the climber. However, when the climber moves above the last anchor, the risk of falling is real, because loose rope accumulates between the climber and the last point of support, i.e., the last anchor. In such a case, the length of the fall is twice the distance between the climber and the last anchor, a kind of pendulum effect. Therefore, the risk of collecting data in a tree largely depends on whether the climber must work above or below the last anchor. In any tree, a risky solution for the climber is obviously to set the last anchor over a branch located in the lowest part of a tree crown, forcing the climber to work above the last anchor, with a constant risk of falling. The safest strategy is to position the climbing rope over the highest solid branch in the tree. Then, the climber can work most of the time below the last anchor, thus minimizing the risk of falling. Sometimes it is not possible to work below the last anchor because of tree structure, or because the highest part of the canopy must be accessed for scientific purposes, such as collecting food for nutritional analyses. Two strategies for the experienced climber can be used to minimize the risks related to gathering data above the last anchor: autoanchoring and dynamic belaying (Cox and Fulsaas, 2003). Autoanchoring is attaching oneself with a second set of climbing gear once positioned above the last anchor (Figure 1e). A shock-absorbing device like a daisy chain (Figure 1e) is recommended for autoanchoring. The expression dynamic belaying refers to the way the energy is absorbed during a fall. In dynamic belaying, the energy of the fall, instead of being absorbed in a small fraction of a second as during static belaying, is spread out and absorbed during a longer period of time, thus substantially increasing the climber’s safety. To understand how the notion of dynamic belaying applies to tree climbing, one can consider the fall factor (Cox and Fulsaas, 2003). Understanding the fall factor is critical if and only if the climber decides to move higher than the last anchor. It does not apply when the climber stays below that anchor. It is a dimensionless number that varies from 0 to 2, and is defined as the distance of the fall, divided by the length of the rope which absorbs the fall. Thus, a 5-m fall absorbed by 50 m of climbing rope results in a fall factor of 0.1 (5 divided by 50 = 0 . 1). The same fall factor value is obtained for a fall of 2 m if the rope which absorbs the energy of the fall is 20 m long (2 / 20 = 0 . 1). The resultant forces are the same because the energy of the longer fall is absorbed by a proportionally longer rope (Cox and Fulsaas, 2003). A fall factor < 0 . 5 is considered by experienced climbers to be safe, between 0.5 and 1.0 is risky, between 1.0 and 1.5 is dangerous, and between 1.5 and 2.0 is extremely dangerous. Extreme danger includes the real possibility that the weakest link in the safety system might break. Even if it does not, the climber can incur severe injuries, notably to the vertebral column. Paradoxically, a longer fall might be safer than a shorter fall. For instance, a free fall of 20 m absorbed by 50 m of rope in an emergent tree is safer for the climber than a free fall of only 2 m but absorbed by 1 m of rope in a small tree (fall factor of 0.4 versus 2, respectively). Although the fall factor assessments are arbitrary, they offer a rough safety guide. A safe climber not only considers the fall factor theory but also puts it in practice while in the tree. Figure 2 presents 2 additional scenarios to illustrate the importance of the fall factor concept, except that this time the length of the fall is identical in both conditions. The difference relates to the climber’s protection strategy. In condition A (Figure 2), the climber ties no knot with the climbing rope, so the latter can run freely at the last anchor and any backup anchors, then she or he moves above the last anchor. In condition B (Figure 2), the climber ties a solid knot at the last anchor, then she or he moves above it. The objective of this exercise is to calculate which of the 2 scenarios is safer. We set in both cases the distance of the climber above the last anchor to 3 m and the distance between the last anchor and the belay on the ground to 15 m. The fall factor in condition A is only 0.33: length of fall of 6 m divided by 18 m of rope which absorbs the energy of the fall, i.e. 3 m of rope between the climber and the last anchor, plus 15 m of rope between the last anchor and the belay. Condition A is thus a safe practice (fall factor < 0 . 5). However, if the tree climber ties a knot at the last anchor as in condition B then she or he moves 3 m above it, the fall factor reaches the maximum, 2: length of fall of 6 m divided by only 3 m of rope absorbing the fall. Only 3 m of rope can absorb the energy of the fall in condition B because the climber has tied a knot at the last anchor; indeed, the 15 m of rope below the last anchor is useless. Condition B is thus an extremely dangerous practice (fall factor > 1 . 5). When applied to tree climbing, the dynamic belaying and fall factor concepts urge tree climbers to let the rope running freely over branches or branch junctions, i.e., no knot using the climbing rope should be tied at these points. When the dynamic belaying principle is applied (Figure 2) and complemented with autoanchoring (Figure 1e), climbing above the last anchor is relatively safe though we recommend that apprentice climbers get experience below the last anchor before attempting an ascent above the last anchor. Appendix II presents the variation of the fall factor in 28 individual trees which were climbed during a 1-yr primate field study in Kibale. It illustrates how the fall factor varies as a function of the climber’s height above the last anchor and the amount of rope available to absorb a potential fall. All climbing conditions involved a fall factor lower than < 1, and were strictly complemented with autoanchoring. When trees are split as small versus emergent, small trees, with a mean fall factor of 0.48, were marginally more dangerous to climb than emergent trees, with a mean fall factor of 0.35 (Mann-Whitney, U = 53.0, p = 0.08). This is best explained by the shorter rope available to absorb a fall in small trees. Another strategy in tree climbing related to dynamic belaying is to increase shock absorption via a dynamic climbing rope versus a static climbing rope. A dynamic rope offers greater elasticity than a static rope. We recommend that inexperienced tree climbers use a dynamic rope. The rope is may be the most important piece of equipment related to the climber’s safety. Modern climbing ropes are composed of a core of braided or parallel nylon filaments encased in a smooth, woven sheath of nylon (Cox and Fulsaas, 2003). Kernmantle ropes are now the only climbing ropes approved by the UIAA. There are two kinds of climbing ropes: dynamic and static. For the same diameter, the dynamic rope offers more elasticity than a static rope and hence can endure higher impacts. Tree climbing rarely involves major falls, but the possibility is real, mostly when the climber moves horizontally in the tree or higher than the last anchor (Figure 2). The pro- tective sheath of a static rope is more abrasion resistant than the sheath of a dynamic rope, and therefore is more appropriate for primate field research. However, a static rope cannot endure severe falls and only experienced tree climbers should consider its purchase. Another factor to consider is the rope diameter. The larger the diameter of a rope, the greater is its energy- absorbing capacity. Descending gear requires a minimum diameter of 10 mm. It is also important to consider whether the rope will be used in a wet en- vironment. Wet ropes become difficult to manage, check fewer falls, and have ca. 30% less strength when they are wet (Cox and Fulsaas, 2003). Overall, we recommend that inexperienced tree climbers purchase a dynamic UIAA-approved 11 mm climbing rope, ideally water-repellent. For the advanced climber, a static 10 mm rope coupled with an explosive quickdraw—a kind a shock-absorbing device attached at the belay—is more appropriate: cheaper, long-lasting sheath, less annoying elasticity while ascending, and lighter. Stepping on a rope is a common form of abusive treatment that grinds cutting particles into and through the sheath (Cox and Fulsaas, 2003). Over time, the particles act like small knives that ...

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... tree largely depends on whether the climber must work above or below the last anchor. In any tree, a risky solution for the climber is obviously to set the last anchor over a branch located in the lowest part of a tree crown, forcing the climber to work above the last anchor, with a constant risk of falling. The safest strategy is to position the climbing rope over the highest solid branch in the tree. Then, the climber can work most of the time below the last anchor, thus minimizing the risk of falling. Sometimes it is not possible to work below the last anchor because of tree structure, or because the highest part of the canopy must be accessed for scientific purposes, such as collecting food for nutritional analyses. Two strategies for the experienced climber can be used to minimize the risks related to gathering data above the last anchor: autoanchoring and dynamic belaying (Cox and Fulsaas, 2003). Autoanchoring is attaching oneself with a second set of climbing gear once positioned above the last anchor (Figure 1e). A shock-absorbing device like a daisy chain (Figure 1e) is recommended for autoanchoring. The expression dynamic belaying refers to the way the energy is absorbed during a fall. In dynamic belaying, the energy of the fall, instead of being absorbed in a small fraction of a second as during static belaying, is spread out and absorbed during a longer period of time, thus substantially increasing the climber’s safety. To understand how the notion of dynamic belaying applies to tree climbing, one can consider the fall factor (Cox and Fulsaas, 2003). Understanding the fall factor is critical if and only if the climber decides to move higher than the last anchor. It does not apply when the climber stays below that anchor. It is a dimensionless number that varies from 0 to 2, and is defined as the distance of the fall, divided by the length of the rope which absorbs the fall. Thus, a 5-m fall absorbed by 50 m of climbing rope results in a fall factor of 0.1 (5 divided by 50 = 0 . 1). The same fall factor value is obtained for a fall of 2 m if the rope which absorbs the energy of the fall is 20 m long (2 / 20 = 0 . 1). The resultant forces are the same because the energy of the longer fall is absorbed by a proportionally longer rope (Cox and Fulsaas, 2003). A fall factor < 0 . 5 is considered by experienced climbers to be safe, between 0.5 and 1.0 is risky, between 1.0 and 1.5 is dangerous, and between 1.5 and 2.0 is extremely dangerous. Extreme danger includes the real possibility that the weakest link in the safety system might break. Even if it does not, the climber can incur severe injuries, notably to the vertebral column. Paradoxically, a longer fall might be safer than a shorter fall. For instance, a free fall of 20 m absorbed by 50 m of rope in an emergent tree is safer for the climber than a free fall of only 2 m but absorbed by 1 m of rope in a small tree (fall factor of 0.4 versus 2, respectively). Although the fall factor assessments are arbitrary, they offer a rough safety guide. A safe climber not only considers the fall factor theory but also puts it in practice while in the tree. Figure 2 presents 2 additional scenarios to illustrate the importance of the fall factor concept, except that this time the length of the fall is identical in both conditions. The difference relates to the climber’s protection strategy. In condition A (Figure 2), the climber ties no knot with the climbing rope, so the latter can run freely at the last anchor and any backup anchors, then she or he moves above the last anchor. In condition B (Figure 2), the climber ties a solid knot at the last anchor, then she or he moves above it. The objective of this exercise is to calculate which of the 2 scenarios is safer. We set in both cases the distance of the climber above the last anchor to 3 m and the distance between the last anchor and the belay on the ground to 15 m. The fall factor in condition A is only 0.33: length of fall of 6 m divided by 18 m of rope which absorbs the energy of the fall, i.e. 3 m of rope between the climber and the last anchor, plus 15 m of rope between the last anchor and the belay. Condition A is thus a safe practice (fall factor < 0 . 5). However, if the tree climber ties a knot at the last anchor as in condition B then she or he moves 3 m above it, the fall factor reaches the maximum, 2: length of fall of 6 m divided by only 3 m of rope absorbing the fall. Only 3 m of rope can absorb the energy of the fall in condition B because the climber has tied a knot at the last anchor; indeed, the 15 m of rope below the last anchor is useless. Condition B is thus an extremely dangerous practice (fall factor > 1 . 5). When applied to tree climbing, the dynamic belaying and fall factor concepts urge tree climbers to let the rope running freely over branches or branch junctions, i.e., no knot using the climbing rope should be tied at these points. When the dynamic belaying principle is applied (Figure 2) and complemented with autoanchoring (Figure 1e), climbing above the last anchor is relatively safe though we recommend that apprentice climbers get experience below the last anchor before attempting an ascent above the last anchor. Appendix II presents the variation of the fall factor in 28 individual trees which were climbed during a 1-yr primate field study in Kibale. It illustrates how the fall factor varies as a function of the climber’s height above the last anchor and the amount of rope available to absorb a potential fall. All climbing conditions involved a fall factor lower than < 1, and were strictly complemented with autoanchoring. When trees are split as small versus emergent, small trees, with a mean fall factor of 0.48, were marginally more dangerous to climb than emergent trees, with a mean fall factor of 0.35 (Mann-Whitney, U = 53.0, p = 0.08). This is best explained by the shorter rope available to absorb a fall in small trees. Another strategy in tree climbing related to dynamic belaying is to increase shock absorption via a dynamic climbing rope versus a static climbing rope. A dynamic rope offers greater elasticity than a static rope. We recommend that inexperienced tree climbers use a dynamic rope. The rope is may be the most important piece of equipment related to the climber’s safety. Modern climbing ropes are composed of a core of braided or parallel nylon filaments encased in a smooth, woven sheath of nylon (Cox and Fulsaas, 2003). Kernmantle ropes are now the only climbing ropes approved by the UIAA. There are two kinds of climbing ropes: dynamic and static. For the same diameter, the dynamic rope offers more elasticity than a static rope and hence can endure higher impacts. Tree climbing rarely involves major falls, but the possibility is real, mostly when the climber moves horizontally in the tree or higher than the last anchor (Figure 2). The pro- tective sheath of a static rope is more abrasion resistant than the sheath of a dynamic rope, and therefore is more appropriate for primate field research. However, a static rope cannot endure severe falls and only experienced tree climbers should consider its purchase. Another factor to consider is the rope diameter. The larger the diameter of a rope, the greater is its energy- absorbing capacity. Descending gear requires a minimum diameter of 10 mm. It is also important to consider whether the rope will be used in a wet en- vironment. Wet ropes become difficult to manage, check fewer falls, and have ca. 30% less strength when they are wet (Cox and Fulsaas, 2003). Overall, we recommend that inexperienced tree climbers purchase a dynamic UIAA-approved 11 mm climbing rope, ideally water-repellent. For the advanced climber, a static 10 mm rope coupled with an explosive quickdraw—a kind a shock-absorbing device attached at the belay—is more appropriate: cheaper, long-lasting sheath, less annoying elasticity while ascending, and lighter. Stepping on a rope is a common form of abusive treatment that grinds cutting particles into and through the sheath (Cox and Fulsaas, 2003). Over time, the particles act like small knives that slice the rope’s nylon filaments. It is hard to decide when to retire a rope. Its condition depends on many factors including frequency of use, the care it has received, its age, and the number of falls it has endured. As a general guideline, a dynamic rope used daily should be retired within a year, while a rope used 2–3 days per week should offer about 2 years of service (Cox and Fulsaas, 2003). A static rope can last twice the time of a dynamic rope. After one very severe fall with fall factor 1.5, any rope should be replaced immediately. The climbing rope is the most important and sensitive equipment, and a safe climber takes great care of it. Knots allow the climber to use the rope for many special purposes: to tie into the rope, to temporarily anchor to a branch, to tie 2 ropes together, to use slings to climb the rope itself, and much more. Climbers rely most heavily on 12 different knots (Cox and Fulsaas, 2003; Vines and Hudson, 1992). A tree climber should practice them until tying them is second nature, including in the dark at cold temperatures. The novice climber should master at least, eyes closed, the following set of tested knots: Figure 8 Follow-through (also called the Flemish Bend), Figure 8 on a Bight, Double or Triple Fisherman’s Knot (also called Grapevine), and one self-rescue knot like the Prusik or Bachman or Klemheist Knot. For intermediate and advanced climbers, there are the Butterfly Knot, Equalizing Figure 8, Water Knot (Ring Bend), Girth Hitch, Stopper Knot, Munter Hitch or Clove Hitch, and for rescuing an injured colleague, the Munter Mule. Contrary to common belief, knots are weaker than the rope used to tie them. Moreover, they do not all offer the same strength. In case of a sudden shock, any chain of safety will break up at the weakest link, most often at the weakest ...

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... again and recovered the original hole. For the 26 species of trees monitored, 20 exhibited no sign of insect or mushroom invasion and were not bleeding. Since local employment is a critical issue for conservation, we recommend that primate researchers hire local climbers who master the use of spurs to climb trees (contra Moffett and Lowman, 1995) but only on those trees that are known not to be spur- sensitive. How dangerous is tree climbing? For the Single Rope Technique, one way to answer this question is to consider whether the tree climber is located above or below the last anchor. An anchor is a support over which the climbing rope is free to move, like a branch in a tree. The last anchor is the highest point of support over which the rope has been passed. When the climber is located below the last anchor, the risk of falling is practically nil because there is no slack in the rope: the latter is attached on the ground at the belay, goes up until it passes over the branch and comes back down to the climber. However, when the climber moves above the last anchor, the risk of falling is real, because loose rope accumulates between the climber and the last point of support, i.e., the last anchor. In such a case, the length of the fall is twice the distance between the climber and the last anchor, a kind of pendulum effect. Therefore, the risk of collecting data in a tree largely depends on whether the climber must work above or below the last anchor. In any tree, a risky solution for the climber is obviously to set the last anchor over a branch located in the lowest part of a tree crown, forcing the climber to work above the last anchor, with a constant risk of falling. The safest strategy is to position the climbing rope over the highest solid branch in the tree. Then, the climber can work most of the time below the last anchor, thus minimizing the risk of falling. Sometimes it is not possible to work below the last anchor because of tree structure, or because the highest part of the canopy must be accessed for scientific purposes, such as collecting food for nutritional analyses. Two strategies for the experienced climber can be used to minimize the risks related to gathering data above the last anchor: autoanchoring and dynamic belaying (Cox and Fulsaas, 2003). Autoanchoring is attaching oneself with a second set of climbing gear once positioned above the last anchor (Figure 1e). A shock-absorbing device like a daisy chain (Figure 1e) is recommended for autoanchoring. The expression dynamic belaying refers to the way the energy is absorbed during a fall. In dynamic belaying, the energy of the fall, instead of being absorbed in a small fraction of a second as during static belaying, is spread out and absorbed during a longer period of time, thus substantially increasing the climber’s safety. To understand how the notion of dynamic belaying applies to tree climbing, one can consider the fall factor (Cox and Fulsaas, 2003). Understanding the fall factor is critical if and only if the climber decides to move higher than the last anchor. It does not apply when the climber stays below that anchor. It is a dimensionless number that varies from 0 to 2, and is defined as the distance of the fall, divided by the length of the rope which absorbs the fall. Thus, a 5-m fall absorbed by 50 m of climbing rope results in a fall factor of 0.1 (5 divided by 50 = 0 . 1). The same fall factor value is obtained for a fall of 2 m if the rope which absorbs the energy of the fall is 20 m long (2 / 20 = 0 . 1). The resultant forces are the same because the energy of the longer fall is absorbed by a proportionally longer rope (Cox and Fulsaas, 2003). A fall factor < 0 . 5 is considered by experienced climbers to be safe, between 0.5 and 1.0 is risky, between 1.0 and 1.5 is dangerous, and between 1.5 and 2.0 is extremely dangerous. Extreme danger includes the real possibility that the weakest link in the safety system might break. Even if it does not, the climber can incur severe injuries, notably to the vertebral column. Paradoxically, a longer fall might be safer than a shorter fall. For instance, a free fall of 20 m absorbed by 50 m of rope in an emergent tree is safer for the climber than a free fall of only 2 m but absorbed by 1 m of rope in a small tree (fall factor of 0.4 versus 2, respectively). Although the fall factor assessments are arbitrary, they offer a rough safety guide. A safe climber not only considers the fall factor theory but also puts it in practice while in the tree. Figure 2 presents 2 additional scenarios to illustrate the importance of the fall factor concept, except that this time the length of the fall is identical in both conditions. The difference relates to the climber’s protection strategy. In condition A (Figure 2), the climber ties no knot with the climbing rope, so the latter can run freely at the last anchor and any backup anchors, then she or he moves above the last anchor. In condition B (Figure 2), the climber ties a solid knot at the last anchor, then she or he moves above it. The objective of this exercise is to calculate which of the 2 scenarios is safer. We set in both cases the distance of the climber above the last anchor to 3 m and the distance between the last anchor and the belay on the ground to 15 m. The fall factor in condition A is only 0.33: length of fall of 6 m divided by 18 m of rope which absorbs the energy of the fall, i.e. 3 m of rope between the climber and the last anchor, plus 15 m of rope between the last anchor and the belay. Condition A is thus a safe practice (fall factor < 0 . 5). However, if the tree climber ties a knot at the last anchor as in condition B then she or he moves 3 m above it, the fall factor reaches the maximum, 2: length of fall of 6 m divided by only 3 m of rope absorbing the fall. Only 3 m of rope can absorb the energy of the fall in condition B because the climber has tied a knot at the last anchor; indeed, the 15 m of rope below the last anchor is useless. Condition B is thus an extremely dangerous practice (fall factor > 1 . 5). When applied to tree climbing, the dynamic belaying and fall factor concepts urge tree climbers to let the rope running freely over branches or branch junctions, i.e., no knot using the climbing rope should be tied at these points. When the dynamic belaying principle is applied (Figure 2) and complemented with autoanchoring (Figure 1e), climbing above the last anchor is relatively safe though we recommend that apprentice climbers get experience below the last anchor before attempting an ascent above the last anchor. Appendix II presents the variation of the fall factor in 28 individual trees which were climbed during a 1-yr primate field study in Kibale. It illustrates how the fall factor varies as a function of the climber’s height above the last anchor and the amount of rope available to absorb a potential fall. All climbing conditions involved a fall factor lower than < 1, and were strictly complemented with autoanchoring. When trees are split as small versus emergent, small trees, with a mean fall factor of 0.48, were marginally more dangerous to climb than emergent trees, with a mean fall factor of 0.35 (Mann-Whitney, U = 53.0, p = 0.08). This is best explained by the shorter rope available to absorb a fall in small trees. Another strategy in tree climbing related to dynamic belaying is to increase shock absorption via a dynamic climbing rope versus a static climbing rope. A dynamic rope offers greater elasticity than a static rope. We recommend that inexperienced tree climbers use a dynamic rope. The rope is may be the most important piece of equipment related to the climber’s safety. Modern climbing ropes are composed of a core of braided or parallel nylon filaments encased in a smooth, woven sheath of nylon (Cox and Fulsaas, 2003). Kernmantle ropes are now the only climbing ropes approved by the UIAA. There are two kinds of climbing ropes: dynamic and static. For the same diameter, the dynamic rope offers more elasticity than a static rope and hence can endure higher impacts. Tree climbing rarely involves major falls, but the possibility is real, mostly when the climber moves horizontally in the tree or higher than the last anchor (Figure 2). The pro- tective sheath of a static rope is more abrasion resistant than the sheath of a dynamic rope, and therefore is more appropriate for primate field research. However, a static rope cannot endure severe falls and only experienced tree climbers should consider its purchase. Another factor to consider is the rope diameter. The larger the diameter of a rope, the greater is its energy- absorbing capacity. Descending gear requires a minimum diameter of 10 mm. It is also important to consider whether the rope will be used in a wet en- vironment. Wet ropes become difficult to manage, check fewer falls, and have ca. 30% less strength when they are wet (Cox and Fulsaas, 2003). Overall, we recommend that inexperienced tree climbers purchase a dynamic UIAA-approved 11 mm climbing rope, ideally water-repellent. For the advanced climber, a static 10 mm rope coupled with an explosive quickdraw—a kind a shock-absorbing device attached at the belay—is more appropriate: cheaper, long-lasting sheath, less annoying elasticity while ascending, and lighter. Stepping on a rope is a common form of abusive treatment that grinds cutting particles into and through the sheath (Cox and Fulsaas, 2003). Over time, the particles act like small knives that slice the rope’s nylon filaments. It is hard to decide when to retire a rope. Its condition depends on many factors including frequency of use, the care it has received, its age, and the number of falls it has endured. As a general guideline, a dynamic rope used daily should be retired within a year, while a rope used 2–3 days per week should offer about 2 years of service (Cox and Fulsaas, 2003). A static rope can last twice the time of a ...

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... much damage could be done to trees accessed with the climbing spurs, we noted whether spur holes were later infested by insects, losing sap, par- asitized by mushrooms, or whether bark formed again and recovered the original hole. For the 26 species of trees monitored, 20 exhibited no sign of insect or mushroom invasion and were not bleeding. Since local employment is a critical issue for conservation, we recommend that primate researchers hire local climbers who master the use of spurs to climb trees (contra Moffett and Lowman, 1995) but only on those trees that are known not to be spur- sensitive. How dangerous is tree climbing? For the Single Rope Technique, one way to answer this question is to consider whether the tree climber is located above or below the last anchor. An anchor is a support over which the climbing rope is free to move, like a branch in a tree. The last anchor is the highest point of support over which the rope has been passed. When the climber is located below the last anchor, the risk of falling is practically nil because there is no slack in the rope: the latter is attached on the ground at the belay, goes up until it passes over the branch and comes back down to the climber. However, when the climber moves above the last anchor, the risk of falling is real, because loose rope accumulates between the climber and the last point of support, i.e., the last anchor. In such a case, the length of the fall is twice the distance between the climber and the last anchor, a kind of pendulum effect. Therefore, the risk of collecting data in a tree largely depends on whether the climber must work above or below the last anchor. In any tree, a risky solution for the climber is obviously to set the last anchor over a branch located in the lowest part of a tree crown, forcing the climber to work above the last anchor, with a constant risk of falling. The safest strategy is to position the climbing rope over the highest solid branch in the tree. Then, the climber can work most of the time below the last anchor, thus minimizing the risk of falling. Sometimes it is not possible to work below the last anchor because of tree structure, or because the highest part of the canopy must be accessed for scientific purposes, such as collecting food for nutritional analyses. Two strategies for the experienced climber can be used to minimize the risks related to gathering data above the last anchor: autoanchoring and dynamic belaying (Cox and Fulsaas, 2003). Autoanchoring is attaching oneself with a second set of climbing gear once positioned above the last anchor (Figure 1e). A shock-absorbing device like a daisy chain (Figure 1e) is recommended for autoanchoring. The expression dynamic belaying refers to the way the energy is absorbed during a fall. In dynamic belaying, the energy of the fall, instead of being absorbed in a small fraction of a second as during static belaying, is spread out and absorbed during a longer period of time, thus substantially increasing the climber’s safety. To understand how the notion of dynamic belaying applies to tree climbing, one can consider the fall factor (Cox and Fulsaas, 2003). Understanding the fall factor is critical if and only if the climber decides to move higher than the last anchor. It does not apply when the climber stays below that anchor. It is a dimensionless number that varies from 0 to 2, and is defined as the distance of the fall, divided by the length of the rope which absorbs the fall. Thus, a 5-m fall absorbed by 50 m of climbing rope results in a fall factor of 0.1 (5 divided by 50 = 0 . 1). The same fall factor value is obtained for a fall of 2 m if the rope which absorbs the energy of the fall is 20 m long (2 / 20 = 0 . 1). The resultant forces are the same because the energy of the longer fall is absorbed by a proportionally longer rope (Cox and Fulsaas, 2003). A fall factor < 0 . 5 is considered by experienced climbers to be safe, between 0.5 and 1.0 is risky, between 1.0 and 1.5 is dangerous, and between 1.5 and 2.0 is extremely dangerous. Extreme danger includes the real possibility that the weakest link in the safety system might break. Even if it does not, the climber can incur severe injuries, notably to the vertebral column. Paradoxically, a longer fall might be safer than a shorter fall. For instance, a free fall of 20 m absorbed by 50 m of rope in an emergent tree is safer for the climber than a free fall of only 2 m but absorbed by 1 m of rope in a small tree (fall factor of 0.4 versus 2, respectively). Although the fall factor assessments are arbitrary, they offer a rough safety guide. A safe climber not only considers the fall factor theory but also puts it in practice while in the tree. Figure 2 presents 2 additional scenarios to illustrate the importance of the fall factor concept, except that this time the length of the fall is identical in both conditions. The difference relates to the climber’s protection strategy. In condition A (Figure 2), the climber ties no knot with the climbing rope, so the latter can run freely at the last anchor and any backup anchors, then she or he moves above the last anchor. In condition B (Figure 2), the climber ties a solid knot at the last anchor, then she or he moves above it. The objective of this exercise is to calculate which of the 2 scenarios is safer. We set in both cases the distance of the climber above the last anchor to 3 m and the distance between the last anchor and the belay on the ground to 15 m. The fall factor in condition A is only 0.33: length of fall of 6 m divided by 18 m of rope which absorbs the energy of the fall, i.e. 3 m of rope between the climber and the last anchor, plus 15 m of rope between the last anchor and the belay. Condition A is thus a safe practice (fall factor < 0 . 5). However, if the tree climber ties a knot at the last anchor as in condition B then she or he moves 3 m above it, the fall factor reaches the maximum, 2: length of fall of 6 m divided by only 3 m of rope absorbing the fall. Only 3 m of rope can absorb the energy of the fall in condition B because the climber has tied a knot at the last anchor; indeed, the 15 m of rope below the last anchor is useless. Condition B is thus an extremely dangerous practice (fall factor > 1 . 5). When applied to tree climbing, the dynamic belaying and fall factor concepts urge tree climbers to let the rope running freely over branches or branch junctions, i.e., no knot using the climbing rope should be tied at these points. When the dynamic belaying principle is applied (Figure 2) and complemented with autoanchoring (Figure 1e), climbing above the last anchor is relatively safe though we recommend that apprentice climbers get experience below the last anchor before attempting an ascent above the last anchor. Appendix II presents the variation of the fall factor in 28 individual trees which were climbed during a 1-yr primate field study in Kibale. It illustrates how the fall factor varies as a function of the climber’s height above the last anchor and the amount of rope available to absorb a potential fall. All climbing conditions involved a fall factor lower than < 1, and were strictly complemented with autoanchoring. When trees are split as small versus emergent, small trees, with a mean fall factor of 0.48, were marginally more dangerous to climb than emergent trees, with a mean fall factor of 0.35 (Mann-Whitney, U = 53.0, p = 0.08). This is best explained by the shorter rope available to absorb a fall in small trees. Another strategy in tree climbing related to dynamic belaying is to increase shock absorption via a dynamic climbing rope versus a static climbing rope. A dynamic rope offers greater elasticity than a static rope. We recommend that inexperienced tree climbers use a dynamic rope. The rope is may be the most important piece of equipment related to the climber’s safety. Modern climbing ropes are composed of a core of braided or parallel nylon filaments encased in a smooth, woven sheath of nylon (Cox and Fulsaas, 2003). Kernmantle ropes are now the only climbing ropes approved by the UIAA. There are two kinds of climbing ropes: dynamic and static. For the same diameter, the dynamic rope offers more elasticity than a static rope and hence can endure higher impacts. Tree climbing rarely involves major falls, but the possibility is real, mostly when the climber moves horizontally in the tree or higher than the last anchor (Figure 2). The pro- tective sheath of a static rope is more abrasion resistant than the sheath of a dynamic rope, and therefore is more appropriate for primate field research. However, a static rope cannot endure severe falls and only experienced tree climbers should consider its purchase. Another factor to consider is the rope diameter. The larger the diameter of a rope, the greater is its energy- absorbing capacity. Descending gear requires a minimum diameter of 10 mm. It is also important to consider whether the rope will be used in a wet en- vironment. Wet ropes become difficult to manage, check fewer falls, and have ca. 30% less strength when they are wet (Cox and Fulsaas, 2003). Overall, we recommend that inexperienced tree climbers purchase a dynamic UIAA-approved 11 mm climbing rope, ideally water-repellent. For the advanced climber, a static 10 mm rope coupled with an explosive quickdraw—a kind a shock-absorbing device attached at the belay—is more appropriate: cheaper, long-lasting sheath, less annoying elasticity while ascending, and lighter. Stepping on a rope is a common form of abusive treatment that grinds cutting particles into and through the sheath (Cox and Fulsaas, 2003). Over time, the particles act like small knives that slice the rope’s nylon filaments. It is hard to decide when to retire a rope. Its condition depends on many factors including frequency of use, the care it has received, its age, and the number of falls it has endured. As a general guideline, a dynamic ...

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... absorbs the fall. Thus, a 5-m fall absorbed by 50 m of climbing rope results in a fall factor of 0.1 (5 divided by 50 = 0 . 1). The same fall factor value is obtained for a fall of 2 m if the rope which absorbs the energy of the fall is 20 m long (2 / 20 = 0 . 1). The resultant forces are the same because the energy of the longer fall is absorbed by a proportionally longer rope (Cox and Fulsaas, 2003). A fall factor < 0 . 5 is considered by experienced climbers to be safe, between 0.5 and 1.0 is risky, between 1.0 and 1.5 is dangerous, and between 1.5 and 2.0 is extremely dangerous. Extreme danger includes the real possibility that the weakest link in the safety system might break. Even if it does not, the climber can incur severe injuries, notably to the vertebral column. Paradoxically, a longer fall might be safer than a shorter fall. For instance, a free fall of 20 m absorbed by 50 m of rope in an emergent tree is safer for the climber than a free fall of only 2 m but absorbed by 1 m of rope in a small tree (fall factor of 0.4 versus 2, respectively). Although the fall factor assessments are arbitrary, they offer a rough safety guide. A safe climber not only considers the fall factor theory but also puts it in practice while in the tree. Figure 2 presents 2 additional scenarios to illustrate the importance of the fall factor concept, except that this time the length of the fall is identical in both conditions. The difference relates to the climber’s protection strategy. In condition A (Figure 2), the climber ties no knot with the climbing rope, so the latter can run freely at the last anchor and any backup anchors, then she or he moves above the last anchor. In condition B (Figure 2), the climber ties a solid knot at the last anchor, then she or he moves above it. The objective of this exercise is to calculate which of the 2 scenarios is safer. We set in both cases the distance of the climber above the last anchor to 3 m and the distance between the last anchor and the belay on the ground to 15 m. The fall factor in condition A is only 0.33: length of fall of 6 m divided by 18 m of rope which absorbs the energy of the fall, i.e. 3 m of rope between the climber and the last anchor, plus 15 m of rope between the last anchor and the belay. Condition A is thus a safe practice (fall factor < 0 . 5). However, if the tree climber ties a knot at the last anchor as in condition B then she or he moves 3 m above it, the fall factor reaches the maximum, 2: length of fall of 6 m divided by only 3 m of rope absorbing the fall. Only 3 m of rope can absorb the energy of the fall in condition B because the climber has tied a knot at the last anchor; indeed, the 15 m of rope below the last anchor is useless. Condition B is thus an extremely dangerous practice (fall factor > 1 . 5). When applied to tree climbing, the dynamic belaying and fall factor concepts urge tree climbers to let the rope running freely over branches or branch junctions, i.e., no knot using the climbing rope should be tied at these points. When the dynamic belaying principle is applied (Figure 2) and complemented with autoanchoring (Figure 1e), climbing above the last anchor is relatively safe though we recommend that apprentice climbers get experience below the last anchor before attempting an ascent above the last anchor. Appendix II presents the variation of the fall factor in 28 individual trees which were climbed during a 1-yr primate field study in Kibale. It illustrates how the fall factor varies as a function of the climber’s height above the last anchor and the amount of rope available to absorb a potential fall. All climbing conditions involved a fall factor lower than < 1, and were strictly complemented with autoanchoring. When trees are split as small versus emergent, small trees, with a mean fall factor of 0.48, were marginally more dangerous to climb than emergent trees, with a mean fall factor of 0.35 (Mann-Whitney, U = 53.0, p = 0.08). This is best explained by the shorter rope available to absorb a fall in small trees. Another strategy in tree climbing related to dynamic belaying is to increase shock absorption via a dynamic climbing rope versus a static climbing rope. A dynamic rope offers greater elasticity than a static rope. We recommend that inexperienced tree climbers use a dynamic rope. The rope is may be the most important piece of equipment related to the climber’s safety. Modern climbing ropes are composed of a core of braided or parallel nylon filaments encased in a smooth, woven sheath of nylon (Cox and Fulsaas, 2003). Kernmantle ropes are now the only climbing ropes approved by the UIAA. There are two kinds of climbing ropes: dynamic and static. For the same diameter, the dynamic rope offers more elasticity than a static rope and hence can endure higher impacts. Tree climbing rarely involves major falls, but the possibility is real, mostly when the climber moves horizontally in the tree or higher than the last anchor (Figure 2). The pro- tective sheath of a static rope is more abrasion resistant than the sheath of a dynamic rope, and therefore is more appropriate for primate field research. However, a static rope cannot endure severe falls and only experienced tree climbers should consider its purchase. Another factor to consider is the rope diameter. The larger the diameter of a rope, the greater is its energy- absorbing capacity. Descending gear requires a minimum diameter of 10 mm. It is also important to consider whether the rope will be used in a wet en- vironment. Wet ropes become difficult to manage, check fewer falls, and have ca. 30% less strength when they are wet (Cox and Fulsaas, 2003). Overall, we recommend that inexperienced tree climbers purchase a dynamic UIAA-approved 11 mm climbing rope, ideally water-repellent. For the advanced climber, a static 10 mm rope coupled with an explosive quickdraw—a kind a shock-absorbing device attached at the belay—is more appropriate: cheaper, long-lasting sheath, less annoying elasticity while ascending, and lighter. Stepping on a rope is a common form of abusive treatment that grinds cutting particles into and through the sheath (Cox and Fulsaas, 2003). Over time, the particles act like small knives that slice the rope’s nylon filaments. It is hard to decide when to retire a rope. Its condition depends on many factors including frequency of use, the care it has received, its age, and the number of falls it has endured. As a general guideline, a dynamic rope used daily should be retired within a year, while a rope used 2–3 days per week should offer about 2 years of service (Cox and Fulsaas, 2003). A static rope can last twice the time of a dynamic rope. After one very severe fall with fall factor 1.5, any rope should be replaced immediately. The climbing rope is the most important and sensitive equipment, and a safe climber takes great care of it. Knots allow the climber to use the rope for many special purposes: to tie into the rope, to temporarily anchor to a branch, to tie 2 ropes together, to use slings to climb the rope itself, and much more. Climbers rely most heavily on 12 different knots (Cox and Fulsaas, 2003; Vines and Hudson, 1992). A tree climber should practice them until tying them is second nature, including in the dark at cold temperatures. The novice climber should master at least, eyes closed, the following set of tested knots: Figure 8 Follow-through (also called the Flemish Bend), Figure 8 on a Bight, Double or Triple Fisherman’s Knot (also called Grapevine), and one self-rescue knot like the Prusik or Bachman or Klemheist Knot. For intermediate and advanced climbers, there are the Butterfly Knot, Equalizing Figure 8, Water Knot (Ring Bend), Girth Hitch, Stopper Knot, Munter Hitch or Clove Hitch, and for rescuing an injured colleague, the Munter Mule. Contrary to common belief, knots are weaker than the rope used to tie them. Moreover, they do not all offer the same strength. In case of a sudden shock, any chain of safety will break up at the weakest link, most often at the weakest knot. The different types of Figure 8 Knots are known to break at 75–80% of rope strength, the Double Fisherman’s Knot at 65– 70%, Water Knot at 60–70%, Overhand Knot and Clove Hitch at 60–65%, and the Square Fisherman’s Knot at a very poor 45% (Luebben, 1993). An 11-mm climbing rope can support 3,000 kg. In this case, if the weakest link is a Square Fisherman’s Knot, then the rope theoretically can break up at 1,300 kg of pressure (45% of 3,000). Regardless of the knot, one should tie it neatly, keeping the separate strands of the knot parallel and free of twists. Figures 1a to 1g present the most important gear necessary to climb trees with the Single Rope Technique. With properly fitted leg loops, the seat harness transfers the force of a fall over the entire pelvis (Cox and Fulsaas, 2003). Hardware loops are desirable to carry descending gear, carabiners, runners of different length, binoculars, field book and other equipment. A chest harness is needed for additional comfort and additional safety. One mechanical ascender—the handle or the Jumar TM (Figures 1a and 1b)—is locked to the seat harness through a runner. A second mechanical ascender— the chest ascender or the Croll TM (Figures 1a to 1b)—is independently locked to the chest harness. Once in the tree crown, the climber uses a daisy chain (Figure 1e) to autoanchor to a branch or a branch junction, independently of the climbing rope. Very short runners or quickdraws like the one on the right of Figure 1g have little value in tree climbing, except for the rappelling system (Fig. 1c and 1d). One should purchase long or very long webbings (120 cm in length), because the climber is often far from suitable branches. Carabiners are another versatile and indispensable tree climbing tool. These ingenious snap-links are used for belaying, rappelling, prusiking, clipping to safety anchors like branches, securing the ...

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Switching spatial scale reveals dominance-dependent social foraging tactics in a wild primate

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When foraging in a social group, individuals are faced with the choice of sampling their environment directly or exploiting the discoveries of others. The evolutionary dynamics of this trade-off have been explored mathematically through the producer-scrounger game, which has highlighted socially exploitative behaviours as a major potential cost of...

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PLOS ONE

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PLOS ONE

Ficus species are keystone plants in tropical rainforests, and hemi-epiphytic figs play a notably important role in forest ecosystems. Because hemi-epiphytic figs have strict germination requirements, germination and establishment stages regulate their populations. Despite the ecological importance of hemi-epiphytic figs in the rainforests, seed dispersal systems by fig-eating animals under natural conditions remain unknown because of the difficulty in tracing the destiny of dispersed seeds in the canopy. Therefore, seed dispersal effectiveness (SDE) has never been evaluated for hemi-epiphytic figs. We evaluated the SDE of hemi-epiphytic figs using qualitative and quantitative components by three relatively large-sized (> 3 kg) arboreal and volant animals in Bornean rainforests that largely depend on fig fruits in their diets: binturongs Arctictis binturong, Mueller’s gibbons Hylobates muelleri, and helmeted hornbills Rhinoplax vigil. The SDE values of binturongs was by far the highest among the three study animals. Meanwhile, successful seed dispersal of hemi-epiphytic figs by gibbons and helmeted hornbills is aleatory and rare. Given that seed deposition determines the fate of hemi-epiphytic figs, the defecatory habits of binturongs, depositing feces on specific microsites in the canopy, is the most reliable dispersal method, compared to scattering feces from the air or upper canopy. We showed that reliable directed dispersal of hemi-epiphytic figs occurs in high and uneven canopy of Bornean rainforests. This type of dispersal is limited to specific animal species, and therefore it may become one of the main factors regulating low-success hemi-epiphytic fig recruitment in Bornean rainforests.

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Habitat loss, poaching and the pet trade have resulted in thousands of orangutans being rescued and taken to rehabilitation centers, many of them infant or juvenile orphans. Besides caring for them, the goal of these centers is to train them for release back into the wild, and critical to the success of post-release survival is their competence in moving through the forest canopy. Orphaned orangutans need regular practice at tree-climbing in order to prepare them for their future life in the wild. Training for this is lacking at rehabilitation centers, however, because caregivers engage with the orphaned orangutans largely on the ground. Orangutan rehabilitation can be greatly improved by training orangutan caregivers in a standardized and safe method of tree climbing so that they can encourage and accompany orangutans to spend more time in the trees. Caregivers trained in tree climbing can also help in wild orangutan rescues, in center maintenance and, through arboreal data collection, in scientific research. We discuss the practical solution of implementing a standardized tree climbing method to orangutan caregivers. Professional climbers have volunteered with the nonprofit Tree Monkey Project to teach orangutan caregivers in Bornean Indonesia and Malaysia. The tree-climbing training program has been successful in allowing caregivers to climb trees alongside orphaned orangutans, encouraging the orangutans to increase the time they spend in the trees and allowing them to hone their agility and skills in moving about in them.

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Dec 2016

The increasing conversion of primary tropical moist forest to secondary forest may have consequences for threatened, large-bodied cavity-nesters, such as the Northern Mealy Amazon (Amazona guatemalae). We determined availability and characteristics of tree-cavities in 24 1-ha survey plots in Los Chimalapas, southeast Mexico, with 9 plots in evergreen forest, 7 in riparian, and 8 in secondary forest. We compared these with 40 parrot nest-trees to determine whether parrots select cavities with specific characteristics for nesting. Over half of Northern Mealy Amazon nests occurred in live trees of Terminalia amazonia (32.5%) and Dialium guianense (20%). Compared with available cavities, the Northern Mealy Amazon selected nest-cavities in significantly larger trees, at a greater height above the ground, with larger internal diameter, and greater depth. In particular, internal diameter and cavity depth predicted whether a cavity was selected as a nest-site by parrots. We found a low density of 2.3 available cavities/ha in the study site, although only 1.6 cavities/ha had characteristics suitable for use as nest-sites by parrots. Cavities in secondary forest occurred in smaller trees, at a lower height, and with shallower depth, where only 0.75 cavities/ha were suitable for nesting by parrots. Our results demonstrate that the Northern Mealy Amazon requires nest-cavities in large, old trees able to form large cavities, the majority of which occur in primary forest. The low density of suitable nest-sites for parrots in secondary forest suggests that increased degradation of primary tropical moist forest may have long-term implications for reproduction of this threatened species.

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