Scarlet-rumped Cacique
Cacicus uropygialis
The scarlet-rumped cacique is sexually dimorphic like many Icteridae, though it mainly concerns size in this species. Males are 23 cm (9 in) long and weigh 68 g (2.4 oz), while the female is 20 cm (8 in) long and weighs 53 g (1.9 oz); This cacique is a slim long-winged bird, with a relatively short tail, blue eyes, and a pale yellow pointed bill. It has mainly black plumage, apart from a scarlet patch on the lower back and upper rump. The female is smaller and a duller black than the male, and the juvenile bird has a brownish tone to the plumage and a brownish-orange rump.
ID text from Wikipedia, CC BY-SA 4.0

Yellow-rumped Cacique
Cacicus cela
The male is on average 28 centimetres (11 in) long and weighs about 104 grams (3.7 oz), with the female 23 centimetres (9.1 in) long and weighing approximately 60 grams (2.1 oz). The yellow-rumped cacique is a slim bird, with a long tail, blue eyes, and a pale yellow pointed bill. It has mainly black plumage, apart from a bright yellow rump, tail base, lower belly and wing "epaulets". The female is duller black than the male, and the juvenile bird resembles the female, but has dark eyes and a brown bill base.
ID text from Wikipedia, CC BY-SA 4.0

Where you might meet both
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Play today's Daily BirdPhotos and recordings are credited to their authors under the licence shown. Full profiles: Scarlet-rumped Cacique and Yellow-rumped Cacique.