Electronic Supplementary Material
The Effects of Habitat Disturbance on Lemurs at Ranomafana National Park, Madagascar
James P. Herrera · Patricia C. Wright · Elise Lauterbur · Lantonirina Ratovonjanahary · Linda L. Taylor
Methods
Cluster Criteria
We followed the methods of Plumptre and Cox (2006) and scored encounters with clusters of lemurs, rather than groups, because all group members were not necessarily present or detected at each encounter. In the case of lemur taxa that typically live in multimale, multifemale social groups (Eulemur rufifrons, Propithecus edwardsi, Varecia variegata, Hapalemur aureus, P. simus), we defined a cluster as all individuals having an interindividual distance from the nearest conspecific neighbor of 50 m. For taxa that typically live in male–female pairs (Eulemur rubriventer, Avahi peyrierasi), we defined a cluster with 2 adults as separate from another conspecific cluster with adult individuals regardless of distance between clusters. If a juvenile individual of a pair-living species was found alone, and an adult pair was located <100 m, we considered that juvenile to be part of the same cluster as the adults; otherwise we recorded it as a solitary individual. Groups of Hapalemur griseus range from male–female pairs to multimale, multifemale groups (Grassi 2001, 2006; Tan 1999, 2000), and we initially applied the same criterion to them as for multimale, multifemale groups. However, during data collection, we found this species only in pairs or solitary and thus we applied the criterion for male–female pairs. Cluster composition does not change under either criterion, sighting frequency for Hapalemur griseus was low, and results for this species should be interpreted with caution.
We recorded cluster composition as the number of adult males, adult females, adolescents/juveniles, infants, and individuals that could not be classified (unknown). We determined sexes by pelage in the taxa that are sexually dichromatic (Eulemur rufifrons and E. rubriventer), by genitalia (if visible), and by the display of sex-specific behaviors, e.g., sternal scent marking in Propithecus edwardsi). For Hapalemur griseus and Avahi peyrierasi, we assumed a cluster with 2 adult individuals to be a male–female pair; individuals were not distinguishable by sex. This assumption might not be completely valid for Hapalemur griseus, which is also known to live in multimale, multifemale groups, so demographic data for this species should be interpreted with caution. We could not distinguish Varecia variegata by sex. We assigned age-class based on the relative size of the individual.
Density Estimation
To estimate density, we calculated the area sampled as the total linear distance surveyed at each site multiplied by the effective sample width. We determined the effective sample width for each species by inspecting histograms of sighting frequencies at 5 m perpendicular distance intervals and recording the upper limit of the interval after which the encounter frequency falls 50% (Irwin et al. 2005[1]; Johnson and Overdorff 1999; Whitesides et al. 1988). As in Whitesides et al. (1988), we added half the mean cluster spread to the effective sample width because the first individuals sighted are likely to be at the periphery of the cluster. We calculated the species-specific effective sample width using:
Effective sample width = 2* [(Nt / Nf ) * FD + ½ S]
wherein Nt = the total number of sightings, Nf = the number of sightings at distances less than the 50% falloff distance, FD = 50% falloff distance, and S = mean cluster spread.
Site / Length (km) / Diurnal repetitions / Diurnal survey effort (km) / Nocturnal repetitions / Nocturnal survey effort (km)Vato 1 / 2 / 13 / 26 / 8 / 16
Vato 2 / 3 / 12 / 36 / 6 / 18
Vato 3 / 2 / 10 / 20 / 8 / 16
Subtotal / 35 / 72 / 22 / 50
Tala 1 / 2 / 11 / 22 / 7 / 14
Tala 2 / 3 / 10 / 30 / 9 / 27
Tala 3 / 2 / 12 / 24 / 4 / 8
Subtotal / 33 / 76 / 20 / 49
Total / 68 / 158 / 42 / 99
Table SI Survey effort on 6 survey routes in Vato and Tala at Ranomafana National Park
Results
Table SII Median scores (range) for forest structure variables measured at points every 100 m along survey routes in Vato and Tala
Vato routes / Tala routes1 / 2 / 3 / Overall / 1 / 2 / 3 / Overall
Canopy cover / 3A
(4) / 5B, C, D
(4) / 3D, E
(4) / 4a
(4) / 2
(5) / 2B
(3) / 1 A, C, E
(3) / 2a
(4)
Canopy height / 3F, G, H
(1) / 3I, J, K
(1) / 4F, I, L, M, N
(2) / 3a
(2) / 1G, J, L, O
(1) / 2M, O, P
(3) / 1H, K, N, P
(1) / 1.5a
(2)
Understory visibility / 2Q, R
(3) / 2 S
(2) / 2T, U, V
(3) / 2a
(3) / 1Q, U, W
(1) / 2 T, W,X
(2) / 1R, S, V, X
(1) / 1a
(2)
Cells with superscript letters in common differed significantly with the Bonferroni correction in pairwise Mann-Whitney U comparisons (p < 0.01).
aSignificant difference between overall scores of the 2 sites (Mann-Whitney U, p < 0.001).
Table SIII Results of random-effects ANOVA comparing encounter rates between Vato and Tala at Ranomafana National Park
Taxon / F / p / Effect size (partial η2)Eulemur rubriventer / 2.39 / 0.13 / 0.04
E. rufifrons / 14.77 / 0.001 / 0.18
Varecia variegata / 5.50 / 0.02 / 0.08
Propithecus edwardsi / 0.88 / 0.35 / 0.01
Hapalemur griseus / 1.01 / 0.32 / 0.02
Total diurnal lemur encounters / 16.30 / 0.001 / 0.20
Avahi peyrierasi / 8.18 / 0.007 / 0.17
Microcebus rufus / 10.67 / 0.002 / 0.21
Total nocturnal lemur encounters / 0.15 / 0.71 / < 0.01
The degrees of freedom for all analyses were 1 and 66 for diurnal taxa and 1 and 40 for nocturnal taxa.
Table SIV Results of random-effects ANOVA comparing encounter rates across 6 survey routes at Ranomafana National Park, 3 each in Vato and Tala
Taxon / F / P / Effect size (partial η2)Eulemur rubriventer / 1.03 / 0.41 / 0.08
E. rufifrons / 4.23 / 0.002 / 0.25
Varecia variegata / 1.47 / 0.21 / 0.11
Propithecus edwardsi / 2.27 / 0.06 / 0.15
Hapalemur griseus / 2.37 / 0.05 / 0.16
Total diurnal lemur encounters / 3.64 / 0.006 / 0.23
Avahi peyrierasi / 2.48 / 0.05 / 0.26
Microcebus rufus / 3.26 / 0.016 / 0.31
Total nocturnal lemur encounters / 0.60 / 0.70 / 0.08
For all tests, the degrees of freedom are 5 and 62 for diurnal taxa and 5 and 36 for nocturnal taxa.
Table SV Cluster size and composition of lemurs encountered during surveys at Ranomafana National Park between June 16 and July 25, 2008
Vato / TalaTaxon / n / Cluster size / No. M / No. F / No. A/J / No. I / No. U / n / Cluster size / No. M / No. F / No. A/J / No. I / No. U
Diurnal
Eulemur rubriventer / 20 / 2.10 ±0.64 / 0.95 ±0.22 / 0.95 ±0.22 / 0.20 ±0.52 / 0 / 0 / 11 / 2.36 ±0.50 / 1.00 / 1.00 / 0.36 ±0.50 / 0 / 0
E. rufifrons / 18 / 6.05 ±4.12 / 2.11 ±1.84 / 1.89 ±1.99 / 0.94 ±1.06 / 0 / 1.11 ±2.61 / 4 / 7.25 ±2.06 / 3.00 ±1.15 / 3.00 ±0.82 / 1.25 ±0.50 / 0 / 0
Hapalemur griseus / 2 / 1.00 / 0 / 0 / 0 / 0 / 1.00 / 5 / 1.80 ±0.45 / 0.80 ±0.45 / 0.80 ±0.45 / 0 / 0 / 0.20 ±0.45
Propithecus edwardsi / 8 / 2.13 ±0.83 / 0.63 ±0.52 / 0.63 ±0.52 / 0.37 ±0.52 / 0.13 ±0.35 / 0.37 ±0.74 / 3 / 3.66 ±3.06 / 0.33 ±0.58 / 0.67 ±0.58 / 0 / 0.33 ±0.58 / 2.33 ±4.04
Avahi peyrierasi / 39 / 1.84 ±0.81 / 0.56 ±0.50 / 0.59 ±0.50 / 0.18 ±0.45 / 0.05 ±0.22 / 0.46 ±0.50 / 20 / 1.65 ±0.67 / 0.55 ±0.51 / 0.55 ±0.51 / 0.05 ±0.22 / 0.05 ±0.22 / 0.45 ±0.51
All reported values other than sample sizes are means ± standard deviation. In some cases, it was not possible to determine the age/sex class of every member of the cluster.
M = adult males; F = adult females; A/J = adolescents/juveniles; I = infants ; U = unknown.
Table SVI Mean (SD) of sighting distances, heights, and the proportion of lemur encounters that we detected visually in Vato and Tala
Species / Mean perpendicular sighting distance (SD) / Mean height(SD) / Proportion of encounters in which we detected individuals visually (n)
Vato / Tala / Vato / Tala / Vato / Tala
Eulemur rufifrons / 10.66 (7.16) / 10.25 (4.63) / 17.00 (4.14)** / 10.5 (3.11) / 67% (18) / 50% (4)
E. rubriventer / 15.48 (12.50) / 8.20 (4.45) / 16.63 (3.85)* / 13.18 (4.12) / 85% (20) / 82% (11)
Hapalemur griseus / 6.5 (0.14) / 9.02 (5.96) / 11.50 (0.71) / 7.90 (6.29) / 100% (2) / 80% (5)
Propithecus edwardsi / 18.79 (13.20) / 14.43 (1.72) / 18.13 (6.20) / 16.00 (5.29) / 75% (8) / 100% (3)
Avahi peyrierasi / 10.85 (7.37) / 8.31 (7.12) / 15.31 (5.33) / 13.25 (5.16) / 97% (39) / 95% (20)
Microcebus rufus / 1.64 (1.46)*** / 6.99 (4.98) / 4.0 (1.22) / 10.10 (7.27) / 100% (8) / 96% (26)
Values in bold are statistically different (Mann-Whitney U test, p < 0.05).
*p = 0.02; **p = 0.004; ***p = 0.007.
Fig. S1 Means plot of encounter rates and 95% confidence intervals around the means for taxa surveyed on 3 routes each in Vato and Tala at Ranomafana National Park. We conducted pairwise comparisons using random-effects ANOVA and Bonferroni adjusted (p < 0.01 considered significant, p < 0.05 also illustrated). (a) Eulemur rubriventer. (b) Eulemur rufifrons. (c) Varecia variegate. (d) Propithecus edwardsi. (e) Hapalemur griseus. (f) Total diurnal lemur encounters. (g) Avahi peyrierasi. (h) Microcebus rufus. (i) Total nocturnal lemur encounters.
(a)
Vato 2 vs. Tala 1: F1, 21 = 7.93, p = 0.01, partial η2 = 0.27
(b)
VATO 1 vs. TALA 2: F1, 21 = 7.07, p = 0.015, partial η2 = 0.25
VATO 1 vs. TALA 3: F1,23 = 17.66, p < 0.001, partial η2 = 0.43
VATO 2 vs. TALA 3: F1,22 = 7.86, p = 0.01, partial η2 = 0.26
VATO 3 vs. TALA 3: F1,20 = 10.91, p = 0.004, partial η2 = 0.35
(c)
(d)
(e)
(f)
VATO 1 vs. TALA 1: F1,21 = 7.84, p = 0.011, partial η2 = 0.27
VATO 2 vs. TALA 2: F1,20 = 13.86, p = 0.001, partial η2 = 0.41
VATO 2 vs. TALA 3: F1, 22 = 12.22, p = 0.002, partial η2 = 0.36
VATO 1 vs. TALA 3: F1,23 = 8.09, p = 0.009, partial η2 = 0.26
VATO 3 vs. TALA 2: F1, 18 = 7.51, p = 0.013, partial η2 = 0.29
VATO 3 vs. TALA 3: F1, 20 = 6.50, p = 0.019, partial η2 = 0.25
(g)
VATO 1 vs. TALA 1: F1,13 = 7.45, p = 0.017, partial η2 = 0.36
VATO 3 vs. TALA 1: F1,13 = 6.50, p = 0.024, partial η2 = 0.33
TALA 1 vs. TALA 2: F1, 14 = 4.89, p = 0.044, partial η2 = 0.26
(h)
VATO 2 vs. TALA 1: F1, 11 = 5.11, p = 0.045, partial η2 = 0.32
VATO 2 vs. TALA 3: F1,8 = 20.35, p = 0.002, partial η2 = 0.72
VATO 3 vs. TALA 2: F1,15 = 5.19, p = 0.038, partial η2 = 0.26
VATO 3 vs. TALA 1: F1,13 = 8.17, p = 0.013, partial η2 = 0.39
VATO 3 vs. TALA 3: F1,10 = 28.27, p < 0.001, partial η2 = 0.74
(i)
References
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[1] We note that the calculation by Irwin et al. (2005) is slightly different in that they used observer-to-animal distances rather than perpendicular sighting distances from the transects. The rest of the calculations are the same.