I went on a 1 week trip to Belize, April 23-May 1 for a combination of birding and exploration of some of the Mayan Sites in the country.   Stayed at 2 locations, Crooked Tree in Belize District and Crystal Paradise in Cayo District.  From each of these locales, went on a variety of tours bird watching and exploring the natural and historic wonders of the country.
The properties I stayed at were the Birds Eye View Lodge at Crooked Tree and the Crystal Paradise Resort in Cayo District.
The Weather was dry, hot and humid.   It only rained once, while in Cayo.  It altered a bit my schedule.  That particular day, went to the Botanic Gardens instead of the scheduled Birding Tour to El Pilar.  In addition, the overall dryness prevented me from taking a boat trip at Crooked Tree since the water level was way to low for their boats.
The only boat trip I did take was to Lamani Mayan Site and, that was definitely well worth it.

Books consulted and used:

1. Birds of Belize by Jones
2. Travellers’ Wildlife Guides Belize & Northern Guatemala by Les Beletsky
3. Annotated Checklist of the Birds of Belize by H. Lee Jones & Vallely

Codes for places visited apply:

Crooked Tree - CT
New River and Lamani - NRL
Crystal Paradise - CP
Xunantunich - X
Cayo - CO (Includes on the road and the Belize Botanical Gardens)
Blue Hole National Park - BH

Bird List (Species in Bold indicate a new species)

1.  Neotropical Cormorant-CT, NRL
2.  Great Blue Heron-NRL
3.  Great Egret-CT
4.  Snowy Egret-CT
5.  Cattle Egret-CT
6.  Little Blue Heron-CT
7.  Tricolored Heron-CT
8.  Green Heron-CT
9.  White Ibis-CT
10.  Roseate Spoonbill-CT
11.  Jabiru Stork-CT
12.  Wood Stork-CT
13.  Black Vulture-CT, CO
14.  Turkey Vulture-CO
15.  Lesser Yellow-headed Vulture-CT
16.  King Vulture-CO
17.  Osprey-CT
18.  Snail Kite-NRL
19.  Black Collared Hawk-CT
20.  White Hawk-CO
21.  Gray Hawk-CT
22.  Roadside Hawk-CO
23.  Bat Falcon-CT
24.  Orange breasted Falcon-CO
25.  Plain Chachalaca-CO
26.  Grey-necked Wood-rail-CT
27.  Yellow-breasted Crake-NRL
28.  Limpkin-CT
29.  Black-necked Stilt-CT
30.  Northern Jacana-CT
31.  Spotted Sandpiper-CT
32.  Caspian Tern-CT
33.  Ruddy Ground Dove-CT, CO
34.  White-tipped Dove-CT
35.  Gray-fronted Dove-CO
36.  Olive –Throated Parakeet-CT
37.  Yellow- Lored Parrot-CT
38.  Red- Lored Parrot-CT, NRL
39.  Groove-billed Ani-CO
40.  Rufous-tailed Hummingbird-CT, CO
41.  Stripe-throated Hermit-BH
42.  Violacious Trogon-CO
43.  Collared Trogon-CO
44.  Slaty-tailed Trogon-CT
45.  Blue-crowned Motmot-CO
46.  Ringed Kingfisher-CT
47.  White-whiskered Puffbird-BH
48.  Rufous-tailed Jacamar-CO
49.  Collared Aracari-CT, CO
50.  Keel-billed Toucan-CO
51.  Acorn Woodpecker-CO
52.  Golden-fronted Woodpecker-CP
53.  Pale-billed Woodpecker-CT, CO, CP
54.  Ivory-billed Woodcreeper-CT
55.  Great Antshrike-BH
56.  Barred Antshrike-CT
57.  Dusky Ant bird-BH
58.  Black-faced Ant-Thrush-BH
59.  Rose-throated Becard-CO
60.  Masked Tityra-CP
61.  Black-crowned Tityra-CP
62.  Slate-Headed Tody Flycatcher-BH
63.  Common Tody Flycatcher-CT
64.  Royal Flycatcher-BH
65.  Eastern Wood-Peewee-CP
66.  Vermillion Flycatcher-CT
67.  Great Crested Flycatcher-CT
68.  Great Kiskadee-CT, CO, CP
69.  Boat-billed Flycatcher-CO
70.  Social Flycatcher-CO
71.  Sulphur-bellied Flycatcher-CO
72.  Piratic Flycatcher-CT
73.  Tropical Kingbird-CT
74.  Fork-Tailed Flycatcher-CO
75.  Brown Jay-X, CO, CP
76.  Mangrove Swallow-CT
77.  Ridgeway Roughwing Swallow-BH
78. Band-Backed Wren-CP, CO
79. Spot Breasted Wren-BH
80. House Wren-CT
81. White-breasted Wood Wren-BH
82. Blue-Gray Gnat Catcher-CT
83. Clay Colored Robin-CO, CP
84. Tropical Mockingbird-CT, CO
85. Yellow Warbler-CT
86. Chestnut Sided Warbler-BH
87. Palm Warbler-CT, CO, CP
88. Black and White Warbler-CO
89. American Redstart-CT
90. Gray Headed Tanager-CO
91. Black-throated Ant-Tanager-CO
92. Hepatic Tanager-CO
93. Blue-Gray Tanager-CT
94. Yellow-Throated Euphonia-CP
95. Olive-backed Euphonia-BH
96. Blue-Black Grassquit-CO
97. White Collared Seedeater-CT
98. Thick-billed Seed-Finch-CO
99. Yellow-faced Grassquit-CT
100.  Olive Sparrow-BH
101.  Grayish Saltator-CO
102.  Black Headed Saltator-CO
103.  Red Winged Blackbird-CT
104.  Melodious Blackbird-CT, CO, CP
105.  Great Tailed Grackle-CT
106.  Hooded Oriole-CT
107.  Yellow Billed Cacique-BH
108.  Montezuma Oropendola-CO