Seabirds inhabit over 70% of the Earth’s surface and represent the final frontier of avian knowledge. Climatic fluctuations, such as the El Niño–Southern Oscillation (ENSO), push these birds to the limits of our knowledge and their survival. ENSO is bimodal. In one of its two phases, the water of the eastern Pacific Ocean is warmer than “normal”; this phase is known as El Niño. ENSO’s cool-water phase is known as La Niña. El Niño is already well underway in mid-2026, and it is projected to strengthen to near-record or record-breaking levels (NOAA 2026a). This happens every fifteen or so years and is increasing in frequency due to climate change (NOAA 2026b, Cai et al. 2014). A few degrees in either direction can seem trivial to humans with our adaptability to a wide range of global climates, and pelagic birds themselves are similarly resilient to temperature fluctuations. Their primary sources of food, however, are not. A warming of just a few degrees in the cool-water Humboldt Current, which runs northward along the western coast of South America, can have catastrophic effects on the food chain.
Humboldt Current feeding frenzy off Chile.
The cold, nutrient-rich waters of the Humboldt Current normally support the most productive marine ecosystem on the planet. 15–20% of the world’s fish catch comes from this narrow band off the Pacific coast of South America (Bennington 2010). Small schooling fish, primarily Peruvian anchoveta (Engraulis ringens), feed on macroplankton, such as krill, that feed on blooms of phytoplankton that are dependent on phosphorus and nitrogen that well up from the depths of the sea. During El Niño, weakening trade winds reduces the upwelling of cold, nutrient-rich water. Sea surface temperatures rise as a result, phytoplankton production collapses, and, this, anchovy populations crash. Those population collapses ripple upward through every link in the food chain. Sardines, squid, and larger fish that prey on anchoveta die off, and the seabirds that depend on all of them are left starving.
For species such as Peruvian Booby, Inca Tern, and Guanay Cormorant, this is an existential threat. A stark example of the effects of a strong El Niño on seabird populations can be seen from surveys in the early 1980s. Peruvian Booby populations plummeted from 2,690,000 breeding birds in 1981–1982 to only 730,000 in 1982-83: a decline of 73% (Tovar et al. 1987). Starved seabirds drift north during El Niño years, searching for cold patches of water with nutrient upwellings and other sources of food. Added to this are the pressures of the latest avian flu outbreak (PAHO/WHO 2026), though it’s unknown how much it is contributing to the presence of these more regularly southern species in Central America in 2026.
Peruvian Booby
While Peruvian Booby has infrequently been seen in Panama over the years, the species’s first known appearance in Costa Rica* was only in 2023, another El Niño year. (A sight record from Beck [1907] was written off by Slud [1967] as a misidentification.) This year, Peruvian Booby was documented in Nicaragua for the first time.
During the 2023 El Niño event, Peruvian Boobies were sighted in Costa Rica off the Osa Peninsula and around the Gulf of Nicoya. At Isla Guayabo near Puntarenas, some Peruvian Boobies were seen associating with over 100 Blue-footed Boobies (another uncommon species in Costa Rica) in addition to the expected Cocos Booby. 2026 has so far been exceptional for Peruvian Booby sightings in Central America. A high count of 14 was tallied in Costa Rica, and as many as 165 were tallied at a single location in Panama.
Blue-footed, Peruvian, and Cocos boobies in the Gulf of Nicoya, Costa Rica, during the 2023 El Niño event.
Inca Tern
Reports of Inca Tern from the Pacific coast of Central America in 2026 include Costa Rica’s northernmost record at Playas del Coco on 30 Jun and El Salvador’s first record on 26 Jul. If not for a 2019 record in Guatemala, these current reports would have each established new (globally) northernmost records for the species. Though Inca Terns in Central America usually occur as individuals or pairs, there are records of as many as 60 in Panama and 13 in Costa Rica.
Guanay Cormorant
El Niño has occasionally led to sightings of Guanay Cormorant in Panama. Related to another El Niño event, as many as 100 were spotted flying north near Enseñada de Guyabito Chiquito, Darién in May 1941 (Ridgley & Gwynne 1989), and a single bird in the Gulf of Panama on 12 Jun 1983 was accompanied by 100 Peruvian Boobies. On 1 Jul 2026, a juvenile Guanay Cormorant was photographed off Punta Culebra and subsequently seen by several observers that afternoon and the following day. Guanay Cormorant has long been expected by birders in Costa Rica. Will this be the year?
Recent High Counts of Other Notable Seabirds
While not providing first country records, several notable species have turned up in southern Central America in 2026. Multiple recent pelagic trips out of Costa Rica have documented new record high counts for the country of Parkinson’s Petrel (26 on 8 Jul), Swallow-tailed Gull (six on 27 Jun), Arctic Tern (four on 14 Jun), Galápagos Shearwater (35 on 22 May), Christmas Shearwater (six on 16 May), and Sooty Shearwater (50 on 11 Mar). Birders in Panama have documented new record high counts of Wedge-rumped Storm-petrel (500+ on 9 May) and Least Storm-petrels (80 on 26 Apr). Whether these high counts are attributable to El Niño, increased observer effort, or some combination of the two is, of course, uncertain
On the Horizon
Which other Pacific Ocean species could be in store as the strong 2026 El Niño continues? A Magellanic Penguin was found in El Salvador in 2007 (Jones and Komar 2007), but this was likely a one-off as it was a juvenile of a migratory species, and ENSO was not in its El Niño phase in 2007. Similarly, a far-out-of-range Spectacled Petrel photographed in Costa Rica in 2025 could have been a random stray. Probably the most likely candidate is Peruvian Pelican, which was photographed north of the equator in Malpelo, Valle de Cauca, Colombia in 2022.
Other Long-shot Candidates
Red-legged Cormorant has been reported only as far north as Guayaquil, Ecuador, but given that a Guanay Cormorant has already ranged into Central America in 2026, this other cormorant species is a contender.
White-chinned Petrel has rarely ranged as far north as Ecuador. Any bird that appears like a Parkinson’s Petrel should be photographed and scrutinized.
Peruvian Diving-Petrel has been reported once from Ecuador and is recorded not infrequently off northern Peru.
Elliot’s Storm-petrel occurs in the Galápagos, not far from southern Central America. This species is similar to Wilson’s Storm-petrel (recently photographed for the first time in Central America), but Elliot’s differs in having a distinct white patch on the belly.
Pelagic trips out of Central America often yield low species variety, as the diversity of pelagic birds is the inverse of landbird species with regard to latitude (i.e., there is little pelagic bird diversity near the equator). El Niño events, especially intense ones, can be devastating for seabird populations but boons for Central American birders. Despite the sad nature of birds struggling for survival, sightings of these species ranging far from their normal haunts are important data for understanding the behavior of pelagic wildlife in response to El Niño events and may help us to better protect them in the decades to come.
The ABA thanks Alvaro Jaramillo for helpful feedback on this article.
Recommended citation: Wenzel, Tyler. 2026. “Intense El Niño Sends Humboldt Current Seabirds to Central America.” North American Birds. 77(2).
References
Beck, R. H. 1907. “Notes from Clipperton and Coccos Islands.” Condor. 9(4): 109–110.
Benningfield, D. 2010. “Humboldt Current.” Science and the Sea podcast. 17(6). University of Texas Marine Science Institute. utmsi.utexas.edu
Cai, W., S. Borlace, M. Lengaigne, P. Van Rensch, M. Collins, G. Vecchi, A. Timmermann, A. Santoso, M. J. McPhaden, L. Wu, M. H. England, G. Wang, E. Guilyardi, and F.-F. Jin. 2014. “Increasing frequency of extreme El Niño events due to greenhouse warming.” Nature Climate Change. 4: 111–116.
eBird: An online database of bird distribution and abundance. Cornell Lab of Ornithology. Accessed 27 Aug 2026. ebird.org
Jones, H. Lee, and O. Komar. 2007. “Central America.” (Summer 2007 report). North American Birds. 61(4): 648–650.
National Oceanic and Atmospheric Administration (NOAA). 2026a. “El Nino forms, expected to strengthen, say NOAA forecasters.” Accessed 27 Aug 2026. noaa.gov
National Oceanic and Atmospheric Administration (NOAA). 2026b. “Historical El Niño/La Niña episodes (1950–present).” Climate Prediction Center. Accessed 27 Aug 2026. origin.cpc.ncep.noaa.gov
Pan American Health Organization/World Health Organization (PAHO/WHO). 2026. “Epidemiological Update: Avian Influenza A(H5N1) in the Americas Region.” Accessed 27 Aug 2026. paho.org
Ridgely, R. S., and J. A. Gwynne, Jr. 1989. A Guide to the Birds of Panama: With Costa Rica, Nicaragua, and Honduras. Second edition. Princeton Univ. Press.
Slud, P. 1967. “The Birds of Cocos Island (Costa Rica).” Bulletin of the American Museum of Natural History. 134: 263–295.
Tovar, H., V. Guillén, and D. Cabrera. 1987. “Reproduction and population levels of Peruvian guano birds, 1980 to 1986.” Journal of Geophysical Research. 92(C13): 14445–14448.
Seabirds inhabit over 70% of the Earth’s surface and represent the final frontier of avian knowledge. Climatic fluctuations, such as the El Niño–Southern Oscillation (ENSO), push these birds to the limits of our knowledge and their survival. ENSO is bimodal. In one of its two phases, the water of the eastern Pacific Ocean is warmer than “normal”; this phase is known as El Niño. ENSO’s cool-water phase is known as La Niña. El Niño is already well underway in mid-2026, and it is projected to strengthen to near-record or record-breaking levels (NOAA 2026a). This happens every fifteen or so years and is increasing in frequency due to climate change (NOAA 2026b, Cai et al. 2014). A few degrees in either direction can seem trivial to humans with our adaptability to a wide range of global climates, and pelagic birds themselves are similarly resilient to temperature fluctuations. Their primary sources of food, however, are not. A warming of just a few degrees in the cool-water Humboldt Current, which runs northward along the western coast of South America, can have catastrophic effects on the food chain.
Humboldt Current feeding frenzy off Chile.
The cold, nutrient-rich waters of the Humboldt Current normally support the most productive marine ecosystem on the planet. 15–20% of the world’s fish catch comes from this narrow band off the Pacific coast of South America (Bennington 2010). Small schooling fish, primarily Peruvian anchoveta (Engraulis ringens), feed on macroplankton, such as krill, that feed on blooms of phytoplankton that are dependent on phosphorus and nitrogen that well up from the depths of the sea. During El Niño, weakening trade winds reduces the upwelling of cold, nutrient-rich water. Sea surface temperatures rise as a result, phytoplankton production collapses, and, this, anchovy populations crash. Those population collapses ripple upward through every link in the food chain. Sardines, squid, and larger fish that prey on anchoveta die off, and the seabirds that depend on all of them are left starving.
For species such as Peruvian Booby, Inca Tern, and Guanay Cormorant, this is an existential threat. A stark example of the effects of a strong El Niño on seabird populations can be seen from surveys in the early 1980s. Peruvian Booby populations plummeted from 2,690,000 breeding birds in 1981–1982 to only 730,000 in 1982-83: a decline of 73% (Tovar et al. 1987). Starved seabirds drift north during El Niño years, searching for cold patches of water with nutrient upwellings and other sources of food. Added to this are the pressures of the latest avian flu outbreak (PAHO/WHO 2026), though it’s unknown how much it is contributing to the presence of these more regularly southern species in Central America in 2026.
Peruvian Booby
While Peruvian Booby has infrequently been seen in Panama over the years, the species’s first known appearance in Costa Rica* was only in 2023, another El Niño year. (A sight record from Beck [1907] was written off by Slud [1967] as a misidentification.) This year, Peruvian Booby was documented in Nicaragua for the first time.
During the 2023 El Niño event, Peruvian Boobies were sighted in Costa Rica off the Osa Peninsula and around the Gulf of Nicoya. At Isla Guayabo near Puntarenas, some Peruvian Boobies were seen associating with over 100 Blue-footed Boobies (another uncommon species in Costa Rica) in addition to the expected Cocos Booby. 2026 has so far been exceptional for Peruvian Booby sightings in Central America. A high count of 14 was tallied in Costa Rica, and as many as 165 were tallied at a single location in Panama.
Blue-footed, Peruvian, and Cocos boobies in the Gulf of Nicoya, Costa Rica, during the 2023 El Niño event.
Inca Tern
Reports of Inca Tern from the Pacific coast of Central America in 2026 include Costa Rica’s northernmost record at Playas del Coco on 30 Jun and El Salvador’s first record on 26 Jul. If not for a 2019 record in Guatemala, these current reports would have each established new (globally) northernmost records for the species. Though Inca Terns in Central America usually occur as individuals or pairs, there are records of as many as 60 in Panama and 13 in Costa Rica.
Guanay Cormorant
El Niño has occasionally led to sightings of Guanay Cormorant in Panama. Related to another El Niño event, as many as 100 were spotted flying north near Enseñada de Guyabito Chiquito, Darién in May 1941 (Ridgley & Gwynne 1989), and a single bird in the Gulf of Panama on 12 Jun 1983 was accompanied by 100 Peruvian Boobies. On 1 Jul 2026, a juvenile Guanay Cormorant was photographed off Punta Culebra and subsequently seen by several observers that afternoon and the following day. Guanay Cormorant has long been expected by birders in Costa Rica. Will this be the year?
Recent High Counts of Other Notable Seabirds
While not providing first country records, several notable species have turned up in southern Central America in 2026. Multiple recent pelagic trips out of Costa Rica have documented new record high counts for the country of Parkinson’s Petrel (26 on 8 Jul), Swallow-tailed Gull (six on 27 Jun), Arctic Tern (four on 14 Jun), Galápagos Shearwater (35 on 22 May), Christmas Shearwater (six on 16 May), and Sooty Shearwater (50 on 11 Mar). Birders in Panama have documented new record high counts of Wedge-rumped Storm-petrel (500+ on 9 May) and Least Storm-petrels (80 on 26 Apr). Whether these high counts are attributable to El Niño, increased observer effort, or some combination of the two is, of course, uncertain
On the Horizon
Which other Pacific Ocean species could be in store as the strong 2026 El Niño continues? A Magellanic Penguin was found in El Salvador in 2007 (Jones and Komar 2007), but this was likely a one-off as it was a juvenile of a migratory species, and ENSO was not in its El Niño phase in 2007. Similarly, a far-out-of-range Spectacled Petrel photographed in Costa Rica in 2025 could have been a random stray. Probably the most likely candidate is Peruvian Pelican, which was photographed north of the equator in Malpelo, Valle de Cauca, Colombia in 2022.
Other Long-shot Candidates
Red-legged Cormorant has been reported only as far north as Guayaquil, Ecuador, but given that a Guanay Cormorant has already ranged into Central America in 2026, this other cormorant species is a contender.
White-chinned Petrel has rarely ranged as far north as Ecuador. Any bird that appears like a Parkinson’s Petrel should be photographed and scrutinized.
Peruvian Diving-Petrel has been reported once from Ecuador and is recorded not infrequently off northern Peru.
Elliot’s Storm-petrel occurs in the Galápagos, not far from southern Central America. This species is similar to Wilson’s Storm-petrel (recently photographed for the first time in Central America), but Elliot’s differs in having a distinct white patch on the belly.
Pelagic trips out of Central America often yield low species variety, as the diversity of pelagic birds is the inverse of landbird species with regard to latitude (i.e., there is little pelagic bird diversity near the equator). El Niño events, especially intense ones, can be devastating for seabird populations but boons for Central American birders. Despite the sad nature of birds struggling for survival, sightings of these species ranging far from their normal haunts are important data for understanding the behavior of pelagic wildlife in response to El Niño events and may help us to better protect them in the decades to come.
The ABA thanks Alvaro Jaramillo for helpful feedback on this article.
Recommended citation: Wenzel, Tyler. 2026. “Intense El Niño Sends Humboldt Current Seabirds to Central America.” North American Birds. 77(2).
References
Beck, R. H. 1907. “Notes from Clipperton and Coccos Islands.” Condor. 9(4): 109–110.
Benningfield, D. 2010. “Humboldt Current.” Science and the Sea podcast. 17(6). University of Texas Marine Science Institute. utmsi.utexas.edu
Cai, W., S. Borlace, M. Lengaigne, P. Van Rensch, M. Collins, G. Vecchi, A. Timmermann, A. Santoso, M. J. McPhaden, L. Wu, M. H. England, G. Wang, E. Guilyardi, and F.-F. Jin. 2014. “Increasing frequency of extreme El Niño events due to greenhouse warming.” Nature Climate Change. 4: 111–116.
eBird: An online database of bird distribution and abundance. Cornell Lab of Ornithology. Accessed 27 Aug 2026. ebird.org
Jones, H. Lee, and O. Komar. 2007. “Central America.” (Summer 2007 report). North American Birds. 61(4): 648–650.
National Oceanic and Atmospheric Administration (NOAA). 2026a. “El Nino forms, expected to strengthen, say NOAA forecasters.” Accessed 27 Aug 2026. noaa.gov
National Oceanic and Atmospheric Administration (NOAA). 2026b. “Historical El Niño/La Niña episodes (1950–present).” Climate Prediction Center. Accessed 27 Aug 2026. origin.cpc.ncep.noaa.gov
Pan American Health Organization/World Health Organization (PAHO/WHO). 2026. “Epidemiological Update: Avian Influenza A(H5N1) in the Americas Region.” Accessed 27 Aug 2026. paho.org
Ridgely, R. S., and J. A. Gwynne, Jr. 1989. A Guide to the Birds of Panama: With Costa Rica, Nicaragua, and Honduras. Second edition. Princeton Univ. Press.
Slud, P. 1967. “The Birds of Cocos Island (Costa Rica).” Bulletin of the American Museum of Natural History. 134: 263–295.
Tovar, H., V. Guillén, and D. Cabrera. 1987. “Reproduction and population levels of Peruvian guano birds, 1980 to 1986.” Journal of Geophysical Research. 92(C13): 14445–14448.
Tyler Wenzel is an avid birder and educator from Pennsylvania who now lives in Costa Rica. He creates bird-focused educational content on social media for the American Birding Association, the International Hummingbird Society, and other bird-focused groups. He is a reviewer and member of the communications team for eBird Costa Rica.
