Supporting tables Table S1. Body mass and foraging height of the five bird species that produced the mobbing calls used in the study. Taxonomy followed del Hoyo et al. (1992-2013). Species Latin name Species English name Body mass (g) Foraging height (m)† Pycnonotus erythropthalmos Spectacled Bulbul 19.2 12.21 Iole olivacea Buff-vented Bulbul 24 11.4 Macronus gularis Pin-striped Tit-babbler 11.83 4 Orthotomus atrogularis Dark-necked Tailorbird 7.68 5.2 Hypothymis azurea Black-naped Monarch 11.1 10.6 Note: † - Calculation of foraging height used the original (primary) set of height values (see Table S3).
Table S2. List of species that were detected at study sites by surveys (S) and that responded to mobbing calls (M), represented by “√”. Taxonomy followed del Hoyo et al. (1992-2013) unless noted otherwise. Species Latin name Species English name Body mass (g) Foraging height (m)† PRIM DEG1 DEG2 DEG3 S M S M S M S M Rollulus rouloul Crested Partridge 216.48 0 √ Argusianus argus Great Argus 1959.93 0.3 √ √ √ Rallina fasciata Red-legged Crake 100 0 √ Treron curvirostra Thick-billed Green-pigeon 134.45 9.74 √ √ √ √ Treron olax Little Green-pigeon 77 12.8 √ √ √ √ Treron vernans Pink-necked Green-pigeon 132 10.3 √ Treron capellei Large Green-pigeon 401.33 12.8 √ Ramphiculus jambu Jambu Fruit-dove 135 3.135 √ Ducula aenea Green Imperial-pigeon 545 17.6 √ √ Chalcophaps indica Grey-capped Emerald Dove 136.54 2.95 √ √ √ √ Psittinus cyanurus Blue-rumped Parrot 11.77 11.5 √ √ √ Loriculus galgulus Blue-crowned Hanging-parrot 28 15.2 √ √
Hierococcyx vagans Moustached Hawk-cuckoo 57.7 7.5 √ Cuculus micropterus Indian Cuckoo 88.75 13.6 √ √ √ Cacomantis sonneratii Banded Bay Cuckoo 33.8 5.65 √ √ Cacomantis merulinus Plaintive Cuckoo 25.3 15.2 √ Chrysococcyx xanthorhynchus Violet Cuckoo 22.37 7.8 √ √ √ Surniculus lugubris Square-tailed Drongo-cuckoo 29.7 17.6 √ Phaenicophaeus sumatranus Chestnut-bellied Malkoha 91.94 7.5 √ Rhinortha chlorophaea Raffles’s Malkoha 51.21 9.1 √ √ √ √ √ Phaenicophaeus curvirostris Chestnut-breasted Malkoha 154 17.6 √ √ Centropus rectunguis Short-toed Coucal 238 12.8 √ Centropus sinensis Greater Coucal 280.7 0.45 √ √ Centropus bengalensis Lesser Coucal 148.91 0.15 √ Hemiprocne comata Whiskered Treeswift 20.63 24 √ Harpactes kasumba Red-naped Trogon 96.89 7.9 √ √ √ √ Harpactes diardii Diard’s Trogon 98.3 4.6 √ √ √ √ Harpactes duvaucelii Scarlet-rumped Trogon 38.85 6.05 √ √ √ √ √ √ √ √
Alcedo meninting Blue-eared Kingfisher 20.42 0.15 √ √ √ Ceyx erithaca Oriental Dwarf-kingfisher 17.79 0.45 √ √ √ Ceyx rufidorsa‡ Rufous-backed Kingfisher 17.79 0.45 √ √ √ √ Lacedo pulchella Banded Kingfisher 47.27 1.75 √ √ √ Halcyon smyrnensis White-breasted Kingfisher 91.4 0 √ Actenoides concretus Rufous-collared Kingfisher 73.47 0 √ √ √ √ Merops philippinus Blue-tailed Bee-eater 34 7.1 √ √ Nyctyornis amictus Red-bearded Bee-eater 71.89 17.4 √ √ √ √ √ √ √ Anorrhinus galeritus Bushy-crested Hornbill 1172 6.45 √ √ √ √ Rhabdotorrhinus corrugatus Wrinkled Hornbill 1590 16.5 √ √ √ Rhyticeros undulatus Wreathed Hornbill 2214.55 14 √ Anthracoceros malayanus Black Hornbill 1050 5.1 √ √ √ √ Buceros rhinoceros Rhinoceros Hornbill 2371.58 14.8 √ √ √ √ Rhinoplax vigil Helmeted Hornbill 2887.64 11.9 √ √ √ Psilopogon chrysopogon Gold-whiskered Barbet 151 17.6 √ √ √ √ Psilopogon rafflesii Red-crowned Barbet 118 17.6 √ √ √ √
Psilopogon mystacophanos Red-throated Barbet 77.4 4.75 √ √ √ Psilopogon henricii Yellow-crowned Barbet 74.1 17.6 √ √ √ Psilopogon duvaucelii Black-eared Barbet 33.3 14 √ √ √ √ Caloramphus hayii Malay Brown Barbet 42.6 9.735 √ √ √ √ Sasia abnormis Rufous Piculet 9.2 2.8 √ √ √ √ √ √ √ Micropternus brachyurus Rufous Woodpecker 85.94 8.85 √ √ √ Dinopium rafflesii Olive-backed Woodpecker 102 4.1 √ Meiglyptes grammithorax Buff-rumped Woodpecker 31.7 17.6 √ √ √ Meiglyptes tukki Buff-necked Woodpecker 53.1 9.735 √ √ √ √ Dryocopus javensis White-bellied Woodpecker 271.4 4.75 √ Blythipicus rubiginosus Maroon Woodpecker 81.91 2.8 √ √ √ Picus puniceus Crimson-winged Woodpecker 79.1 3.135 √ √ √ √ Chrysophlegma humii Checker-throated Yellownape 99.73 8 √ √ √ √ Chrysophlegma miniaceum Banded Woodpecker 97.29 9.735 √ √ √ Chrysocolaptes validus Orange-backed Woodpecker 102 4.1 √ √ Corydon sumatranus Dusky Broadbill 140 8 √ √ √
Cymbirhynchus macrorhynchos Black-and-red Broadbill 59.4 1.9 √ √ Eurylaimus javanicus Banded Broadbill 78.2 3.95 √ √ √ √ √ Eurylaimus ochromalus Black-and-yellow Broadbill 33.3 3.45 √ √ √ √ √ √ Calyptomena viridis Green Broadbill 58.5 3.95 √ √ √ √ √ √ √ √ Pitta granatina Garnet Pitta 62 0.3 √ √ Pitta sordida Hooded Pitta 64.5 0 √ Pitta guajana Banded Pitta 81.5 0 √ √ √ √ Hemipus hirundinaceus Black-winged 10.2 20 √ √ √ √ √ √ √ Tephrodornis virgatus Large Wood-shrike 37.8 12 √ √ √ √ √ Pericrocotus flammeus Scarlet Minivet 23.3 20 √ Aegithina viridissima Green Iora 13.4 20 √ √ √ √ √ √ √ √ Aegithina tiphia Common Iora 12 17.6 √ Chloropsis cyanopogon Lesser Green Leafbird 22 14 √ √ √ √ √ √ √ √ Chloropsis sonnerati Greater Green Leafbird 45.8 14 √
Hemixos cinereus Cinereous Bulbul 32.5 11.4 √ Dicrurus aeneus Bronzed Drongo 26 16.2 √ √ √ √ Dicrurus paradiseus Greater Racket-tailed Drongo 85.82 10.15 √ √ √ √ √ √ √ √ Oriolus xanthonotus Dark-throated Oriole 45 14.55 √ √ √ √ √ √ √ Irena puella Asian Fairy-bluebird 64.9 14 √ √ √ √ √ √ Platylophus galericulatus Crested Jay 77.89 9.65 √ Platysmurus leucopterus Black Magpie 180 9.65 √ √ √ √ √ √ Corvus enca Slender-billed Crow 251 4.45 √ √ √ Sitta frontalis Velvet-fronted Nuthatch 16.5 10.3 √ √ √ √ Pellorneum capistratum Black-capped Babbler 25.1 0.3 √ √ √ √ Pellorneum buettikoferi Sumatra Babbler 17.1 1.5 √ Trichastoma rostratum White-chested Babbler 17.8 0 √ √ √ √ √ Trichastoma bicolor Ferruginous Babbler 27.2 0.6 √ √ √ √ √ Malacocincla malaccensis Short-tailed Babbler 21.4 0.75 √ √ √ √ Malacocincla sepiarium Horsfield’s Babbler 25.5 2.2 √ √ Malacopteron magnirostre Moustached Babbler 19.34 8 √ √ √ √ √ √ √ √
Eupetes macrocerus Rail-babbler 101 0 √ √ √ Trichixos pyrropygus Rufous-tailed Shama 40.9 3.135 √ √ √ √ √ √ √ Enicurus leschenaulti White-crowned Forktail 33.8 0 √ √ √ Orthotomus atrogularis Dark-necked Tailorbird 7.68 5.2 √ √ √ √ √ √ √ Orthotomus ruficeps Ashy Tailorbird 8.1 9.735 √ √ Orthotomus sericeus Rufous-tailed Tailorbird 10.8 0.3 √ √ √ √ √ √ √ √ Prinia familiaris Bar-winged Prinia 9.68 7.375 √ Rhinomyias olivaceus Fulvous-chested 15.7 18.6 √ √ √ Rhinomyias umbratilis Grey-chested 18.2 7.8 √ √ √ √ √ √ √ √ Eumyias thalassinus Asian Verditer-flycatcher 18.1 11.2 √ Ficedula dumetoria Rufous-chested Flycatcher 9.4 1.5 √ Culicicapa ceylonensis Grey-headed 7.7 10.85 √ √ Cyornis unicolor Pale Blue-flycatcher 21 13.2 √ √ √
Cyornis caerulatus Large-billed Blue-flycatcher 22.49 4.75 √ √ Rhipidura perlata Spotted Fantail 13.4 7.2 √ √ √ √ Hypothymis azurea Black-naped Monarch 11.1 10.6 √ √ √ √ √ √ √ √ Philentoma velata Maroon-breasted Philentoma 26.1 8 √ Philentoma pyrhoptera Rufous-winged Philentoma 16.9 6.7 √ √ √ √ √ √ √ √ Terpsiphone paradisi Asian Paradise-flycatcher 19.23 15.4 √ √ √ √ Gracula religiosa Common Hill Myna 192 9.65 √ √ √ √ Anthreptes simplex Plain Sunbird 8.93 7.25 √ √ √ √ √ √ √ √ Anthreptes malacensis Brown-throated Sunbird 11.33 7.15 √ Anthreptes rhodolaemus Red-throated Sunbird 13.1 9.65 √ √ √ √ √ √ Chalcoparia singalensis Ruby-cheeked Sunbird 8.2 10.3 √ √ √ √ √ √ √ Hypogramma hypogrammicum Purple-naped Sunbird 11.42 7.15 √ √ √ √ √ √ Leptocoma sperata Purple-throated Sunbird 11.33 7.15 √ Aethopyga siparaja Crimson Sunbird 6.7 5.85 √ Arachnothera longirostra Little Spiderhunter 12.46 2.8 √ √ √ √ √ √ √ √ Arachnothera crassirostris Thick-billed Spiderhunter 16 7.25 √
Arachnothera robusta Long-billed Spiderhunter 25.37 14 √ √ √ √ √ √ Arachnothera flavigaster Spectacled Spiderhunter 38.4 11.6 √ √ √ √ √ √ Arachnothera chrysogenys Yellow-eared Spiderhunter 23.2 14 √ √ √ Arachnothera modesta Grey-breasted Spiderhunter 26.4 12.7 √ √ √ √ √ √ √ √ Prionochilus thoracicus Scarlet-breasted Flowerpecker 8.9 9.65 √ √ √ Prionochilus maculatus Yellow-breasted Flowerpecker 7.95 9 √ √ √ √ √ √ Prionochilus percussus Crimson-breasted Flowerpecker 6 10.85 √ √ √ √ √ √ √ √ Dicaeum trigonostigma Orange-bellied Flowerpecker 7.1 9.65 √ √ √ √ √ √ √ Note: † - Calculation of foraging height used the original (primary) set of height values (see Table S3). ‡ - This species was formerly considered a separate species from its sister species Ceyx erithaca, and is now recognized by del Hoyo et al. (1992-2013) as the same species as Ceyx erithaca. In this study, we treated it as a standalone species. Reference del Hoyo, J., Elliott, A. & Christie, D. (1992-2013) Handbook of the Birds of the World. Lynx Edicions.