Ingo Arndt / White-necked jacobin (Florisuga mellivora) hummingbird, male, in flight. Costa Rica.

Glenn Bartley/ BIA / Black Jacobin (Melanotrochilus fuscus) hummingbird feeding on flower nectar, Atlantic Rainforest, Brazil

Five Films / Black jacobin humingbird (Florisuga fusca) feeding from a nectar feeder, Reserva Ecologica de Guapiacu, Rio de Janeiro, Brazil, 2015.

Five Films / Black jacobin hummingbird (Florisuga fusca) hovering and feeding from a nectar feeder, Reserva Ecologica de Guapiacu, Rio de Janeiro, Brazil, 2015.

Hanne & Jens Eriksen / Jacobin cuckoo (Clamator jacobinus) on twig, India, February.

Hermann Brehm / Jacobin Cuckoo (Clamator jacobinus) fledgling begging for food from Arrow-marked Babbler (Turdoides jardineii ) Kwara, Botswana June

Hermann Brehm / Jacobin Cuckoo (Clamator jacobinus) fledgling begging for food from Arrow-marked Babbler (Turdoides jardineii ) Kwara, Botswana June

Hermann Brehm / Jacobin Cuckoo (Clamator jacobinus) fledgling begging for food from Arrow-marked Babbler (Turdoides jardineii ) Kwara, Botswana June

Luiz Claudio Marigo / Black jacobin (Florisuga fusca) Atlantic Rainforest, Serra Bonita Private Natural Heritage Reserve (RPPN Serra Bonita), Camacan, Southern Bahia State, Eastern Brazil.

Luiz Claudio Marigo / Black jacobin (Florisuga fusca) Atlantic Rainforest, Serra Bonita Private Natural Heritage Reserve (RPPN Serra Bonita), Camacan, Southern Bahia State, Eastern Brazil.

Luiz Claudio Marigo / Black jacobin (Florisuga fusca) Atlantic Rainforest, Serra Bonita Private Natural Heritage Reserve (RPPN Serra Bonita), Camacan, Southern Bahia State, Eastern Brazil.

Luiz Claudio Marigo / Black jacobin (Florisuga fusca) perched on branch in mountainous Atlantic Rainforest of Serra Bonita Natural Private Heritage Reserve (RPPN Serra Bonita) municipality of Camacan, Southern Bahia State,...

Luiz Claudio Marigo / Black jacobin (Florisuga fusca) perched in Atlantic Rainforest, Serrinha do Alambari Environmental Protection Area, Rio de Janeiro State, Southeastern Brazil.

Luiz Claudio Marigo / Black jacobin (Florisuga fusca) perched in Atlantic Rainforest, Serrinha do Alambari Environmental Protection Area, Rio de Janeiro State, Southeastern Brazil.

Gabriel Rojo / Black jacobin {Melanotrochilus fuscus} Iguazu NP, Brazil / Argentina

Glenn Bartley/ BIA / Black Jacobin (Melanotrochilus fuscus) hummingbird feeding on flower nectar, Atlantic Rainforest, Brazil

Agustin Esmoris / Black Jacobin (Melanotrochilus fuscus) hummingbird feeding on flower nectar, Argentina

Vishal Jadhav / Jacobin cuckoo (Clamator jacobinus) calling whilst perched on branch and looking around, Pune, India.

Vishal Jadhav / Jacobin cuckoo (Clamator jacobinus) looking around before vocalising and jumping out of frame whilst flapping, Pune, India.

Ashish & Shanthi Chandola / Pied cuckoo (Clamator jacobinus), Ranthambhore NP, Rajasthan, India

Ashish & Shanthi Chandola / Pied cuckoo (Clamator jacobinus), Ranthambhore National Park, Rajasthan, India

Ashish & Shanthi Chandola / Pied cuckoo (Clamator jacobinus), Ranthambhore National Park, Rajasthan, India

Ann & Steve Toon / Jacobin cuckoo (Clamator jacobinus), Kruger national park, South Africa, November.