A dataset of bird inventory records at Cloudbridge Nature Reserve, Talamanca Mountains, Costa Rica, between March 2016 and May 2020.

Study Extent

For all sampling types except camera trapping, data was collected along the trails of Cloudbridge Nature Reserve. Point count and call-playback survey data was collected at sampling stations marked with a fixed and labelled marker. Walking survey and photographic data was collected anywhere along the trail system. Camera trapping data was collected at 16 locations throughout the part of the reserve south of the Río Chirripó Pacífico. The camera traps were arrayed in a grid approximately 300 m apart.

Sampling

Bird presence was determined from several data sources, including: 1) point count monitoring, 2) walking surveys, 3) owl call-playback surveys, 4) camera trap images, and 5) photographs.

Quality Control

Training. All field crew for point count and walking surveys were trained on site for 2–3 weeks and were required to pass a visual bird identification test prior to beginning surveys. Each test consisted of 30 images, each shown for 15–45 seconds, of a different random selection of species that had been identified in or near the reserve or were potentially present in the area (approximately 300 species). Testing was repeated until a passing grade of 28/30 correct identifications was reached. Audio identification was not tested due to the difficulty of training accurate bird song identification skills for 300 species in short-term field crew (typically 2–3 month periods). As such, visual identification was prioritized in order to have a higher degree of confidence in the accuracy of the resulting identifications.

Method steps

1. Data collection. Bird presence was determined from several data sources, including: 1) point count monitoring, 2) walking surveys, 3) owl call-playback surveys, 4) camera trap images, and 5) photographs. Point Count Monitoring. The bulk of the data was collected as part of a long-term monitoring study beginning on 14 March 2016 and continuing to 29 May 2020 with some gaps in data collection due to a lack of field staff, including: June–July 2016, March–June 2017, September–December 2018, and January 2019. From March 2016 to October 2017, point counts were conducted at 24 sites. In October 2017, tropical storm Nate caused severe flooding along the rivers ending reliable access to the 4 northernmost point count sites after that date. After 15 December 2017, five replacement sites were added in the southern part of the reserve and sampling continued until 29 May 2020 only at the 25 point count sites in the southern part of the reserve. Four or 5 sites were surveyed each day starting at 06:00 and finishing between 09:00 and 10:00, with all sites surveyed once a week. Daily site survey order was reversed weekly to help prevent temporal bias. Point counts lasted 20 min, conducted by one or two observers (typically two). Within a 25 m radius of a fixed marker, from the ground to the top of the canopy, all birds utilizing the habitat were identified and recorded. Visual identifications were prioritized due to training difficulties (see training section), but audio identifications were also recorded and the type of identification noted. Audio identifications were only included in this inventory when the species was also confirmed by visual identification. Birds seen soaring in the area or transiting the site were also identified but during periods of high volume were less of a priority to record. A total of 3440 point count surveys were conducted. Walking surveys. Walking surveys were conducted in conjunction with both the point count monitoring study (14 March 2016 to 29 May 2020) and a study on mixed species feeding flocks (MSF) (12 February to 19 June 2019). Walking surveys were conducted along all the trails of the reserve, including those not covered by the point count surveys, and were particularly important for surveying the northern part of the reserve where access was too unreliable for regular sampling after October 2017. During the point count monitoring study, walking surveys were conducted on alternating days for a total of five surveys every two weeks. Walking surveys occurred in between point count sites and continued after point counts had been completed. They started at 06:00 and finished at 12:00. During the MSF study, walking surveys were conducted each weekday along four routes covering most of the reserve beginning at 06:00 and lasting 3–4 h. Species were tallied for specific segments of the trails being walked. A total of 267 walking surveys were conducted for the monitoring study and 80 for the MSF study. Owl call-playback surveys. Owl species were surveyed using call-playback between March 2016 and January 2020 with data collection gaps including: March–April, June–July, and October–December in 2017; January and July in 2018; and May and September–October in 2019. Costa Rican Pygmy Owl (Glaucidium costaricanum), Unspotted Saw-whet Owl (Aegolius ridgwayi), Tropical Screech-Owl (Megascops choliba), Bare-shanked Screech-Owl (Megascops clarkii), and Mottled Owl (Ciccaba virgata) were included in the study based on previous study results (Paradis 2007) and known Costa Rican owl ranges. Striped Owl (Asio clamator) was added in April 2016 after one was observed in the reserve. Owl surveys were conducted at the same 24 locations as the point counts, with the exception of the five sites added in 2017. The four northern sites were dropped in October 2017 due to loss of access, leaving 20 survey sites. A total of 625 surveys were conducted, with all but the first 24 surveyed for all six owl species. Call-playback surveys started at 18:30 and were completed by 00:00. Five sites were surveyed each evening, and each site was only surveyed once a month to prevent habituation to the calls. Surveys began with 3 min of silence, followed by a 2-min playback, repeated until all owl calls had been played in order of smallest owl to largest, finishing with 3 min of silence. Playbacks were composed of a mixture of alarm and song calls downloaded from Xeno-Canto (Xeno-Canto Foundation 2005–2019). Camera trap images. Bird records were supplemented by camera trap images collected in the reserve. Most camera trap data was collected between 13 May 2019 and 21 May 2020 along a grid of 16 locations spaced approximately 300 m apart throughout the reserve, some near the trail system, but most at more remote locations. As data from the camera trap study was not fully processed at the time of writing, it was only used to supplement monthly presence data for some species. Additional camera trap images from recreational cameras were available prior to May 2019, and were sometimes used as voucher photos, but not used for presence data. Photographs. Photographs taken either during or outside of surveys were obtained from staff, interns, researchers, volunteers, and visitors. In addition to serving as records of species presence, these photos were used as voucher photos for the identified species. Location and date were confirmed for each photo, ranging from 23 February 2007 to 25 April 2021. Photographs taken outside of surveys were added as unique records to the species record tables in the supplementary material.

All birds were identified to species based on the most current taxonomic designations at the time of publication. Only species for which a voucher photo was collected from within the reserve are included in the dataset.

1. Accipiter bicolor
   common name: Bicolored Hawk rank: species
2. Amaurospiza concolor
   common name: Blue Seedeater rank: species
3. Amazilia edward
   common name: Snowy-bellied Hummingbird rank: species
4. Amazilia tzacatl
   common name: Rufous-tailed Hummingbird rank: species
5. Anabacerthia variegaticeps
   common name: Scaly-throated Foliage-gleaner rank: species
6. Antrostomus saturatus
   common name: Dusky Nightjar rank: species
7. Aramides cajaneus
   common name: Gray-cowled Wood-Rail rank: species
8. Arremon brunneinucha
   common name: Chestnut-capped Brushfinch rank: species
9. Arremon crassirostris
   common name: Sooty-faced Finch rank: species
10. Atlapetes albinucha
    common name: White-naped Brushfinch rank: species
11. Atlapetes tibialis
    common name: Yellow-thighed Brushfinch rank: species
12. Aulacorhynchus prasinus
    common name: Northern Emerald-Toucanet rank: species
13. Basileuterus culicivorus
    common name: Golden-crowned Warbler rank: species
14. Basileuterus melanogenys
    common name: Black-cheeked Warbler rank: species
15. Basileuterus melanotis
    common name: Costa Rican Warbler rank: species
16. Bolborhynchus lineola
    common name: Barred Parakeet rank: species
17. Bubulcus ibis
    common name: Cattle Egret rank: species
18. Buteo brachyurus
    common name: Short-tailed Hawk rank: species
19. Buteo jamaicensis
    common name: Red-tailed Hawk rank: species
20. Buteo platypterus
    common name: Broad-winged Hawk rank: species
21. Buteogallus urubitinga
    common name: Great Black Hawk rank: species
22. Campylopterus hemileucurus
    common name: Violet Sabrewing rank: species
23. Campylorhamphus pusillus
    common name: Brown-billed Scythebill rank: species
24. Cantorchilus elutus
    common name: Isthmian Wren rank: species
25. Caracara cheriway
    common name: Crested Caracara rank: species
26. Cardellina canadensis
    common name: Canada Warbler rank: species
27. Cardellina pusilla
    common name: Wilson's Warbler rank: species
28. Cathartes aura
    common name: Turkey Vulture rank: species
29. Catharus aurantiirostris
    common name: Orange-billed Nightingale-Thrush rank: species
30. Catharus frantzii
    common name: Ruddy-capped Nightingale-Thrush rank: species
31. Catharus fuscater
    common name: Slaty-backed Nightingale-Thrush rank: species
32. Catharus gracilirostris
    common name: Black-billed Nightingale-Thrush rank: species
33. Catharus ustulatus
    common name: Swainson's Thrush rank: species
34. Chaetura vauxi
    common name: Vaux's Swift rank: species
35. Chamaepetes unicolor
    common name: Black Guan rank: species
36. Chlorophonia callophrys
    common name: Golden-browed Chlorophonia rank: species
37. Chlorospingus flavopectus
    common name: Common Chlorospingus rank: species
38. Chlorospingus pileatus
    common name: Sooty-capped Chlorospingus rank: species
39. Chlorostilbon assimilis
    common name: Garden Emerald rank: species
40. Ciccaba virgata
    common name: Mottled Owl rank: species
41. Cinclus mexicanus
    common name: American Dipper rank: species
42. Coereba flaveola
    common name: Bananaquit rank: species
43. Colaptes rubiginosus
    common name: Golden-olive Woodpecker rank: species
44. Colibri cyanotus
    common name: Lesser Violetear rank: species
45. Colibri delphinae
    common name: Brown Violetear rank: species
46. Columbina talpacoti
    common name: Ruddy Ground Dove rank: species
47. Contopus cooperi
    common name: Olive-sided Flycatcher rank: species
48. Contopus lugubris
    common name: Dark Pewee rank: species
49. Contopus sordidulus
    common name: Western Wood-Pewee rank: species
50. Coragyps atratus
    common name: Black Vulture rank: species
51. Cranioleuca erythrops
    common name: Red-faced Spinetail rank: species
52. Cyanerpes cyaneus
    common name: Red-legged Honeycreeper rank: species
53. Cyanolyca argentigula
    common name: Silvery-throated Jay rank: species
54. Cyclarhis gujanensis
    common name: Rufous-browed Peppershrike rank: species
55. Dacnis venusta
    common name: Scarlet-thighed Dacnis rank: species
56. Diglossa plumbea
    common name: Slaty Flowerpiercer rank: species
57. Dives dives
    common name: Melodious Blackbird rank: species
58. Doryfera ludovicae
    common name: Green-fronted Lancebill rank: species
59. Dryobates fumigatus
    common name: Smoky-brown Woodpecker rank: species
60. Dryobates villosus
    common name: Hairy Woodpecker rank: species
61. Elaenia flavogaster
    common name: Yellow-bellied Elaenia rank: species
62. Elaenia frantzii
    common name: Mountain Elaenia rank: species
63. Elanoides forficatus
    common name: Swallow-tailed Kite rank: species
64. Elvira chionura
    common name: White-tailed Emerald rank: species
65. Empidonax atriceps
    common name: Black-capped Flycatcher rank: species
66. Empidonax flavescens
    common name: Yellowish Flycatcher rank: species
67. Empidonax flaviventris
    common name: Yellow-bellied Flycatcher rank: species
68. Eubucco bourcierii
    common name: Red-headed Barbet rank: species
69. Eugenes spectabilis
    common name: Talamanca Hummingbird rank: species
70. Eupherusa eximia
    common name: Stripe-tailed Hummingbird rank: species
71. Euphonia elegantissima
    common name: Elegant Euphonia rank: species
72. Euphonia hirundinacea
    common name: Yellow-throated Euphonia rank: species
73. Euphonia imitans
    common name: Spot-crowned Euphonia rank: species
74. Falco rufigularis
    common name: Bat Falcon rank: species
75. Fregata magnificens
    common name: Magnificent Frigatebird rank: species
76. Geotrygon montana
    common name: Ruddy Quail-Dove rank: species
77. Glyphorynchus spirurus
    common name: Wedge-billed Woodcreeper rank: species
78. Grallaria guatimalensis
    common name: Scaled Antpitta rank: species
79. Harpagus bidentatus
    common name: Double-toothed Kite rank: species
80. Heliodoxa jacula
    common name: Green-crowned Brilliant rank: species
81. Heliomaster longirostris
    common name: Long-billed Starthroat rank: species
82. Heliothryx barroti
    common name: Purple-crowned Fairy rank: species
83. Henicorhina leucophrys
    common name: Gray-breasted Wood-Wren rank: species
84. Icterus galbula
    common name: Baltimore Oriole rank: species
85. Ixothraupis guttata
    common name: Speckled Tanager rank: species
86. Klais guimeti
    common name: Violet-headed Hummingbird rank: species
87. Lampornis castaneoventris
    common name: White-throated Mountain-gem rank: species
88. Legatus leucophaius
    common name: Piratic Flycatcher rank: species
89. Leiothlypis peregrina
    common name: Tennessee Warbler rank: species
90. Lepidocolaptes affinis
    common name: Spot-crowned Woodcreeper rank: species
91. Leptopogon superciliaris
    common name: Slaty-capped Flycatcher rank: species
92. Leptotila verreauxi
    common name: White-tipped Dove rank: species
93. Lophotriccus pileatus
    common name: Scale-crested Pygmy-Tyrant rank: species
94. Margarornis rubiginosus
    common name: Ruddy Treerunner rank: species
95. Megarynchus pitangua
    common name: Boat-billed Flycatcher rank: species
96. Megascops clarkii
    common name: Bare-shanked Screech-Owl rank: species
97. Melanerpes formicivorus
    common name: Acorn Woodpecker rank: species
98. Melanerpes rubricapillus
    common name: Red-crowned Woodpecker rank: species
99. Micrastur ruficollis
    common name: Barred Forest-Falcon rank: species
100. Microcerculus marginatus
     common name: Scaly-breasted Wren rank: species
101. Milvago chimachima
     common name: Yellow-headed Caracara rank: species
102. Mionectes olivaceus
     common name: Olive-striped Flycatcher rank: species
103. Mitrephanes phaeocercus
     common name: Tufted Flycatcher rank: species
104. Mniotilta varia
     common name: Black-and-white Warbler rank: species
105. Molothrus aeneus
     common name: Bronzed Cowbird rank: species
106. Momotus lessonii
     common name: Lesson's Motmot rank: species
107. Morphnarchus princeps
     common name: Barred Hawk rank: species
108. Myadestes melanops
     common name: Black-faced Solitaire rank: species
109. Myiarchus tuberculifer
     common name: Dusky-capped Flycatcher rank: species
110. Myioborus miniatus
     common name: Slate-throated Redstart rank: species
111. Myioborus torquatus
     common name: Collared Redstart rank: species
112. Myiodynastes hemichrysus
     common name: Golden-bellied Flycatcher rank: species
113. Myiothlypis fulvicauda
     common name: Buff-rumped Warbler rank: species
114. Myiozetetes granadensis
     common name: Gray-capped Flycatcher rank: species
115. Myiozetetes similis
     common name: Social Flycatcher rank: species
116. Myrmotherula schisticolor
     common name: Slaty Antwren rank: species
117. Nothocercus bonapartei
     common name: Highland Tinamou rank: species
118. Nyctidromus albicollis
     common name: Common Pauraque rank: species
119. Odontophorus guttatus
     common name: Spotted Wood-Quail rank: species
120. Odontophorus leucolaemus
     common name: Black-breasted Wood-Quail rank: species
121. Oreothlypis gutturalis
     common name: Flame-throated Warbler rank: species
122. Ortalis cinereiceps
     common name: Gray-headed Chachalaca rank: species
123. Pachyramphus albogriseus
     common name: Black-and-white Becard rank: species
124. Pachyramphus versicolor
     common name: Barred Becard rank: species
125. Pachysylvia decurtata
     common name: Lesser Greenlet rank: species
126. Parkesia motacilla
     common name: Louisiana Waterthrush rank: species
127. Patagioenas fasciata
     common name: Band-tailed Pigeon rank: species
128. Patagioenas subvinacea
     common name: Ruddy Pigeon rank: species
129. Phaethornis guy
     common name: Green Hermit rank: species
130. Pharomachrus mocinno
     common name: Resplendent Quetzal rank: species
131. Pheucticus ludovicianus
     common name: Rose-breasted Grosbeak rank: species
132. Pheucticus tibialis
     common name: Black-thighed Grosbeak rank: species
133. Pheugopedius rutilus
     common name: Rufous-breasted Wren rank: species
134. Philodice bryantae
     common name: Magenta-throated Woodstar rank: species
135. Philydor rufum
     common name: Buff-fronted Foliage-gleaner rank: species
136. Phyllomyias burmeisteri
     common name: Rough-legged Tyrannulet rank: species
137. Piaya cayana
     common name: Squirrel Cuckoo rank: species
138. Picumnus olivaceus
     common name: Olivaceous Piculet rank: species
139. Pionus senilis
     common name: White-crowned Parrot rank: species
140. Piranga bidentata
     common name: Flame-colored Tanager rank: species
141. Piranga leucoptera
     common name: White-winged Tanager rank: species
142. Piranga rubra
     common name: Summer Tanager rank: species
143. Pitangus sulphuratus
     common name: Great Kiskadee rank: species
144. Platyrinchus mystaceus
     common name: White-throated Spadebill rank: species
145. Premnoplex brunnescens
     common name: Spotted Barbtail rank: species
146. Psarocolius wagleri
     common name: Chestnut-headed Oropendola rank: species
147. Pseudocolaptes lawrencii
     common name: Buffy Tuftedcheek rank: species
148. Psilorhinus morio
     common name: Brown Jay rank: species
149. Ptiliogonys caudatus
     common name: Long-tailed Silky-flycatcher rank: species
150. Pygochelidon cyanoleuca
     common name: Blue-and-white Swallow rank: species
151. Pyrilia haematotis
     common name: Brown-hooded Parrot rank: species
152. Pyrrhura hoffmanni
     common name: Sulphur-winged Parakeet rank: species
153. Ramphocelus passerinii costaricensis
     common name: Scarlet-rumped Tanager (Cherrie's) rank: subspecies
154. Rhynchocyclus brevirostris
     common name: Roadside Hawk rank: species
155. Rupornis magnirostris
     common name: Roadside Hawk rank: species
156. Saltator maximus
     common name: Buff-throated Saltator rank: species
157. Sayornis nigricans
     common name: Black Phoebe rank: species
158. Sclerurus mexicanus
     common name: Tawny-throated Leaftosser rank: species
159. Scytalopus argentifrons
     common name: Silvery-fronted Tapaculo rank: species
160. Seiurus aurocapilla
     common name: Ovenbird rank: species
161. Selasphorus flammula
     common name: Volcano Hummingbird rank: species
162. Selasphorus scintilla
     common name: Scintillant Hummingbird rank: species
163. Serpophaga cinerea
     common name: Torrent Tyrannulet rank: species
164. Setophaga fusca
     common name: Blackburnian Warbler rank: species
165. Setophaga pitiayumi
     common name: Tropical Parula rank: species
166. Setophaga virens
     common name: Black-throated Green Warbler rank: species
167. Sittasomus griseicapillus
     common name: Olivaceous Woodcreeper rank: species
168. Sphyrapicus varius
     common name: Yellow-bellied Sapsucker rank: species
169. Spinus psaltria
     common name: Lesser Goldfinch rank: species
170. Spinus xanthogastrus
     common name: Yellow-bellied Siskin rank: species
171. Spizaetus ornatus
     common name: Ornate Hawk-Eagle rank: species
172. Sporophila corvina
     common name: Variable Seedeater rank: species
173. Stelgidopteryx ruficollis
     common name: Southern Rough-winged Swallow rank: species
174. Stelgidopteryx serripennis
     common name: Northern Rough-winged Swallow rank: species
175. Stilpnia larvata
     common name: Golden-hooded Tanager rank: species
176. Streptoprocne rutila
     common name: Chestnut-collared Swift rank: species
177. Streptoprocne zonaris
     common name: White-collared Swift rank: species
178. Syndactyla subalaris
     common name: Lineated Foliage-gleaner rank: species
179. Tangara dowii
     common name: Spangle-cheeked Tanager rank: species
180. Tangara gyrola
     common name: Bay-headed Tanager rank: species
181. Tangara icterocephala
     common name: Silver-throated Tanager rank: species
182. Thraupis episcopus
     common name: Blue-gray Tanager rank: species
183. Thraupis palmarum
     common name: Palm Tanager rank: species
184. Thripadectes rufobrunneus
     common name: Streak-breasted Treehunter rank: species
185. Tiaris olivaceus
     common name: Yellow-faced Grassquit rank: species
186. Tigrisoma fasciatum
     common name: Fasciated Tiger-Heron rank: species
187. Tityra semifasciata
     common name: Masked Tityra rank: species
188. Tolmomyias sulphurescens
     common name: Yellow-olive Flycatcher rank: species
189. Troglodytes aedon
     common name: House Wren rank: species
190. Troglodytes ochraceus
     common name: Ochraceous Wren rank: species
191. Trogon collaris
     common name: Collared Trogon rank: species
192. Turdus grayi
     common name: Clay-colored Thrush rank: species
193. Turdus plebejus
     common name: Mountain Thrush rank: species
194. Tyrannus melancholicus
     common name: Tropical Kingbird rank: species
195. Vermivora chrysoptera
     common name: Golden-winged Warbler rank: species
196. Vireo carmioli
     common name: Yellow-winged Vireo rank: species
197. Vireo flavifrons
     common name: Yellow-throated Vireo rank: species
198. Vireo leucophrys
     common name: Brown-capped Vireo rank: species
199. Vireo philadelphicus
     common name: Philadelphia Vireo rank: species
200. Xenops rutilans
     common name: Streaked Xenops rank: species
201. Zentrygon chiriquensis
     common name: Chiriqui Quail-Dove rank: species
202. Zentrygon costaricensis
     common name: Buff-fronted Quail-Dove rank: species
203. Zimmerius parvus
     common name: Mistletoe Tyrannulet rank: species
204. Zonotrichia capensis
     common name: Rufous-collared Sparrow rank: species

Data was collected from Cloudbridge Nature Reserve and adjacent habitats. Cloudbridge is located on the Pacific slope of Cerro Chirripó near the entrance to Cerro Chirripó National Park. The Río Chirripó Pacífico runs east-west through the reserve and joins with the the Río Uran, which runs north-south, in the center of the reserve. Cloudbridge is bounded on the north and south by private forested land, on the east by Cerro Chirripó National Park and a disused cattle pasture, and on the west by active cattle pasture. Altitudes of data collection ranged between 1550 m and 2200 m a.s.l.