Online Resource 1 (supplementary table)
Article: Implications of newly-formed seed-dispersal mutualisms between birds and introduced
plants in northern California, USA
Journal: Biological Invasions
Author: Clare E. Aslan, University of California-Santa Cruz, caslan@ucsc.edu
Supplementary table. Estimated removal of study species fruits by birds of different behavioral
guilds. FG = feeding guild. No. obs. = the number of periods in which bird species was observed
in the relevant tree species. Average flock size is derived from scan sampling data, and is given
per tree. FDI = flock dispersal importance (average number of fruits dispersed per minute per
tree by this bird species over all observed stands); FRI = flock removal importance (for seed
predators, average number of fruits removed per minute per tree). ODI = overall dispersal
importance (FDI x number of observations in which this bird species was present in observed
trees); ORI = overall removal importance (for seed predators, FRI x number of observations in
which this bird species was present). Each subtable pertains to a different study species: a.
Triadica sebifera; b. Ligustrum lucidum; c. Olea europaea; d. Heteromeles arbutifolia. Since
seed predators do not disperse seeds but may contribute significantly to fruit removal, tables are
subdivided by handling guild. Note that yellow-rumped warbler is considered a seed predator on
T. sebifera, because it forages by scraping the waxy aril off the seed but never swallowing and
dispersing the seed itself; this behavior makes the fruit less attractive to other foragers. For L.
lucidum, by contrast, the yellow-rumped warbler swallows fruits whole and is therefore
considered a disperser.
a. Triadica sebifera
Bird Species
FG
No. obs.
Avg. flock size
FDI
ODI
European starling
Pulse
7
0.104 ± 0.013
3.02 ± 0.92
21.12 ± 6.47
American robin
Pulse
13
0.095 ± 0.023
0.54 ± 0.27
7.07 ± 3.46
Northern flicker
Background
8
0.018 ± 0.002
0.50 ± 0.13
4.02 ± 1.08
Nuttall’s woodpecker
Background
6
0.069 ± 0.009
0.32 ± 0.20
1.94 ± 1.19
Western-scrub jay
Background
21
0.024 ± 0.002
0.08 ± 0.03
1.66 ± 0.73
Northern mockingbird
Background
10
0.014 ± 0.002
0.13 ± 0.07
1.26 ± 0.73
American crow
Pulse
3
0.009 ± 0.001
0.33 ± 0.27
0.98 ± 0.80
Cedar waxwing
Pulse
7
0.080 ± 0.012
0.03 ± 0.03
0.24 ± 0.22
Hermit thrush
Background
1
0.007 ± 0.000
0.14 ± 0.20
0.14 ± 0.20
Black phoebe
Background
5
0.009 ± 0.001
0.01 ± 0.01
0.03 ± 0.03
FRI
ORI
Handling guild: Dispersers
Handling guild: Seed predators
Yellow-rumped warbler
Background
45
0.351 ± 0.030
0.01 ± 0.01
0.59 ± 0.25
House finch
Background
28
0.093 ± 0.010
0.02 ± 0.01
0.56 ± 0.21
Lesser goldfinch
Background
20
0.074 ± 0.007
0.01 ± 0.01
0.25 ± 0.18
Dark-eyed junco
Background
8
0.025 ± 0.004
0.01 ± 0.01
0.06 ± 0.06
House sparrow
Background
4
0.008 ± 0.001
0.005±0.003
0.02 ± 0.01
b. Ligustrum lucidum
Bird Species
FG
No. obs.
Avg. flock size
FDI
ODI
Cedar waxwing
Pulse
13
0.096 ± 0.014
16.78 ± 3.70
217.97 ± 48.12
American robin
Pulse
17
0.101 ± 0.015
3.39 ± 0.50
57.61 ± 8.49
Northern mockingbird
Background
27
0.015 ± 0.001
0.84 ± 0.21
22.58 ± 5.64
Hermit thrush
Background
21
0.068 ± 0.011
1.04 ± 0.26
21.75 ± 5.38
Northern flicker
Background
6
0.011 ± 0.001
2.21 ± 0.48
13.27 ± 2.85
Yellow-rumped warbler
Background
38
0.137 ± 0.012
0.15 ± 0.05
5.71 ± 2.07
Western-scrub jay
Background
27
0.030 ± 0.003
0.19 ± 0.06
5.13 ± 1.75
Pulse
7
0.047 ± 0.004
0.05 ± 0.04
0.36 ± 0.27
FRI
ORI
Handling guild: Dispersers
American crow
Handling guild: Seed predators
House finch
Background
26
0.139 ± 0.019
5.72 ± 0.79
148.79 ± 20.49
Dark-eyed junco
Background
14
0.079 ± 0.010
1.37 ± 0.23
19.20 ± 3.16
Purple finch
Background
4
0.010 ± 0.001
0.14 ± 0.08
0.54 ± 0.32
Mourning dove
Background
2
0.040 ± 0.004
0.21 ± 0.21
0.43 ± 0.43
White-crowned Sparrow
Background
3
0.033 ± 0.000
0.07 ± 0.00
0.21 ± 0.00
c. Olea europaea
Bird Species
FG
No. obs.
Avg. flock size
FDI
ODI
European starling
Pulse
22
0.143 ± 0.018
4.91 ± 1.58
108.00 ± 34.81
Western-scrub jay
Background
50
0.046 ± 0.004
0.55 ± 0.22
27.36 ± 11.04
Western meadowlark
Background
5
0.242 ± 0.000
1.30 ± 0.70
6.49 ± 3.52
American robin
Pulse
24
0.081 ± 0.012
0.23 ± 0.08
5.58 ± 1.80
Wild turkey
Pulse
1
0.039 ± 0.000
2.28 ± 0.00
2.28 ± 0.00
Western bluebird
Pulse
4
0.027 ± 0.003
0.13 ± 0.09
0.51 ± 0.36
Background
12
0.019 ± 0.003
0.04 ± 0.03
0.48 ± 0.36
Pulse
6
0.030 ± 0.005
0.04 ± 0.04
0.24 ± 0.26
Background
21
0.035 ± 0.008
0.002 ± 0.002
0.002 ± 0.05
FRI
ORI
Handling guild: Dispersers
Northern mockingbird
American crow
Hermit thrush
Handling guild: Seed predators
California quail
Pulse
3
0.063 ± 0.003
0.70 ± 0.00
2.10 ± 0.00
White-crowned sparrow
Background
28
0.156 ± 0.015
0.07 ± 0.04
1.91 ± 1.14
Spotted towhee
Background
14
0.103 ± 0.007
0.09 ± 0.02
1.31 ± 0.33
Golden-crowned sparrow
Background
28
0.142 ± 0.015
0.005 ± 0.003
0.15 ± 0.09
d. Heteromeles arbutifolia
Bird Species
FG
No. obs.
Avg. flock size
FDI
ODI
Background
39
0.038 ± 0.004
1.87 ± 0.26
72.92 ± 10.26
American robin
Pulse
22
0.231 ± 0.028
2.57 ± 0.32
56.52 ± 6.94
Cedar waxwing
Pulse
6
0.082 ± 0.007
6.76 ± 3.05
40.54 ± 18.27
Background
33
0.041 ± 0.004
0.62 ± 0.16
20.39 ± 5.15
Western bluebird
Pulse
2
0.020 ± 0.002
0.76 ± 0.39
1.51 ± 0.79
Western-scrub jay
Background
23
0.023 ± 0.001
0.004 ± 0.002
0.09 ± 0.05
FRI
ORI
Handling guild: Dispersers
Hermit thrush
Northern mockingbird
Handling guild: Seed predators
Golden-crowned sparrow
Background
12
0.012 ± 0.001
0.66 ± 0.45
7.87 ± 5.39
House finch
Background
4
0.006 ± 0.001
0.60 ± 0.29
2.41 ± 1.15
Purple finch
Background
1
0.005 ± 0.000
0.39 ± 0.55
0.39 ± 0.55
Spotted towhee
Background
10
0.028 ± 0.002
0.01 ± 0.01
0.14 ± 0.10