The blue-footed booby is a large seabird native to the Galapagos Islands and other islands along the coasts of Peru and Chile. Known for their bright blue feet and comical courtship displays, blue-footed boobies have become icons of the unique wildlife found in the Galapagos. But are these charismatic birds at risk of extinction?
Quick Answer
The blue-footed booby is currently classified as Least Concern on the IUCN Red List of Threatened Species. This means that while their population numbers have declined in some areas, overall the species is still abundant and widespread throughout its range.
Overview of the Blue-Footed Booby
The blue-footed booby (Sula nebouxii) is a large seabird in the Sulidae family, which comprises ten species of gannets and boobies. They have a wingspan of up to 1.5 meters and weigh around 1-1.5 kg. As their name suggests, male and female blue-footed boobies both have bright blue feet, though females’ feet tend to be duller in color. Their plumage is otherwise mostly brown with some white on the undersides.
Blue-footed boobies are found along the Pacific coasts of South and Central America from southern California down to Peru, with their largest populations centered around the Galapagos Islands. They nest colonially in trees, bushes, or on the ground on offshore islands and rocks. Breeding occurs from March through September, peaking between May and July. Females lay 1-3 eggs which hatch after about 40 days. Chicks fledge at 3-4 months old.
These seabirds feed by plunge-diving from heights of up to 30 meters, crashing into the ocean at high speeds to catch fish and squid. They typically forage within about 40 km of their nesting sites. An irrigation system in their nasal passages helps them expel seawater after diving. Their bright blue feet play an important role in mating displays but otherwise have no known function.
Population and Conservation Status
Globally, the blue-footed booby has an extremely large range and population size. The worldwide population is estimated at around 200,000 to 300,000 mature individuals. In 2018, the IUCN Red List classified the blue-footed booby as Least Concern, meaning they are not currently vulnerable to extinction.
However, while still abundant overall, local population numbers appear to be declining in some regions, especially in the southern and northern extremes of their range. The largest populations remain centered in the Galapagos Islands of Ecuador. In California, their breeding sites have declined from over 20 to just one remaining today.
Region | Breeding Population Trend |
---|---|
Southern California | Declining significantly |
Mexico | Apparently declining but data deficient |
Galapagos Islands (Ecuador) | Stable or increasing |
Coastal Peru | Apparently declining but data deficient |
Coastal Chile | Apparently declining but data deficient |
These downward trends are likely driven by a combination of threats, mainly:
- Fisheries bycatch
- Introduced predators at nesting sites
- Human disturbance and habitat loss
- Climate change and severe weather
- Reduced food availability from overfishing and environmental changes
However, overall the blue-footed booby remains common and widespread. Ongoing population monitoring and protection of key breeding sites will be important for the species’ long-term outlook.
Population in the Galapagos Islands
The Galapagos Islands are home to an estimated 20,000-35,000 breeding pairs of blue-footed boobies, making up a significant portion of the global population. Here, their numbers appear to be stable or even increasing in some locations compared to past decades.
For example, on Isla Plaza Sur in the Galapagos there were an estimated 500-700 breeding pairs in 1971. Surveys in 2001-2005 found over 5,000 nests estimated to represent around half the island’s population at the time. On Isla Genovesa in the northern Galapagos, annual surveys found the breeding population increased from around 6,400 pairs in 1999 to over 10,000 pairs in 2009.
Possible reasons for these increases could include reduced disturbance and habitat protection, abundant food availability in most years, and an absence of terrestrial predators.
Declining Populations in Peru and Chile
In contrast to the Galapagos, blue-footed booby colonies along the coasts of Peru and Chile appear to be declining based on limited data. Blue-footed boobies have disappeared from several historic breeding sites along the coast of Peru. In Chile, a 2015 assessment found breeding sites had declined from 13 to just 6, several of which had much lower numbers than past records.
For example, on Isla Pan de Azucar along the northern Chilean coast, the estimated breeding population declined sharply from around 20,000 individuals in 1961 to just 2,000-3,000 birds in 2015. Causes may include introduced predators, human disturbance, habitat loss, bycatch in fisheries, and climate fluctuations resulting in less favorable foraging conditions.
Declines in Mexico and Southern California
In Mexico, blue-footed boobies are showing concerning population declines, though data is limited. Breeding sites along the Pacific Coast of Baja California have been gradually abandoned, with ten known colonies remaining by the 1990s compared to over twenty historically. These declines are likely driven by gillnet fisheries bycatch, human coastal development, egg collection, and disturbance.
Southern California was once the northernmost limit of the blue-footed booby’s range. In the early 1900s, there were breeding colonies on the Channel Islands and other offshore rocks. But populations declined steeply in the mid 1900s. The last known colony at the Channel Islands disappeared in the 1960s. Currently, just one small colony of less than 100 pairs remains at the offshore San Benito Islands.
Threats and Conservation Challenges
The specific threats facing blue-footed booby populations vary across their range. But overall, the main conservation challenges include:
Fisheries Bycatch
Foraging blue-footed boobies are vulnerable to becoming caught in fishing nets and longlines. Gillnet fisheries pose the greatest risk, especially along the Pacific coast of the Americas where gillnet use remains widespread. Even occasional bycatch mortality events can significantly impact local breeding populations.
Invasive Species
Non-native predators introduced to nesting islands cause severe impacts. Feral cats prey on booby chicks and eggs on many islands. Rats eat eggs and young chicks. Some islands in the Galapagos have undertaken rat eradication efforts to help protect blue-footed booby nesting sites.
Human Disturbance
Blue-footed boobies are sensitive to human disturbance while nesting, which can cause nest abandonment and colony failure. Human presence on islands and coastal development reduces available habitat. Boobies may also become entangled in marine debris.
Climate Change Effects
Warming ocean temperatures, rising sea levels, and increasing severity of El NiƱo events may reduce food availability or quality. Nesting habitat could also be degraded by rising seas and severe weather. The impacts remain uncertain but likely to grow.
Food Web Alterations
Overfishing and environmental changes have reduced forage fish populations in some areas like Peru. Lack of prey affects booby nutrition and reproductive success. Sufficient fish populations near colonies are critical.
Conservation Actions Needed
To ensure the long-term survival of blue-footed booby populations, the following conservation strategies should be prioritized across their range:
- Protect breeding colonies from human disturbance and encroachment
- Control and prevent introduction of invasive predators like cats and rats
- Reduce fisheries bycatch through use of selective gears and spatial closures
- Maintain plentiful prey populations by managing fisheries sustainably
- Monitor population trends and adjust conservation as needed
- Mitigate climate change by reducing carbon emissions globally
The blue-footed booby remains the least concern species despite some worrying regional declines. But ongoing conservation action will be needed to protect populations into the future as threats are expected to grow.
Conclusion
The blue-footed booby is currently a relatively abundant seabird across its range along the Pacific coasts of the Americas. While not at imminent risk of extinction, local populations are declining in areas like California, Mexico, Peru, and Chile. The reasons likely include fisheries bycatch, habitat loss, human disturbance, introduced predators, reduced food availability, and climate change effects.
But substantial populations remain stable or increasing in protected areas like the Galapagos Islands. For now, the IUCN still categorizes the blue-footed booby as Least Concern globally. However, their status merits continued monitoring. Conservation actions are needed across their range to manage fisheries sustainably, control predators, protect breeding colonies, and mitigate climate change in order to support thriving booby populations into the future.