The bird kingdom encompasses a vast array of winged creatures that fill our skies and enrich our lives. With over 10,000 species living today, birds are the most diverse group of land vertebrates on Earth. Their sizes range from tiny hummingbirds weighing just a few grams to huge ostriches and emus that can reach over 9 feet tall and weigh more than 350 pounds. But just how big is the bird kingdom in terms of sheer numbers and mass?
Total Number of Individual Birds
Estimating the total global population of birds is an extremely difficult task, but various scientific studies have attempted to quantify the number of individual birds on Earth at a given time. According to a 2020 study published in the Proceedings of the National Academy of Sciences, there are approximately 50 billion individual birds inhabiting the planet today. This staggering figure was reached by analyzing citizen science bird population data from over 600,000 locations worldwide. The study suggests that there has been a decline of approximately 3 billion birds since 1970, emphasizing the need for continued conservation efforts.
Year | Estimated Total Number of Individual Birds Worldwide |
---|---|
1970 | 50 billion |
2020 | 47 billion |
While 50 billion individual birds may seem like an extraordinarily high number, it is important to note that birds are found on every continent and thrive in diverse habitats ranging from Arctic tundra to tropical rainforests. The most abundant bird species, including red-billed queleas, brown-headed cowbirds, and ring-billed gulls, can have populations numbering into the tens or hundreds of millions globally. Also, small songbirds and seabirds that flock together and reproduce rapidly, like European starlings and Leach’s storm petrels, collectively add up to billions of individuals worldwide.
Total Bird Biomass
Another way to measure the size of the avian world is to look at total bird biomass, which represents the combined weight of all individual birds. In 2018, a study published in Proceedings of the National Academy of Sciences estimated the total biomass of all the world’s birds to be approximately 70 billion kg. For perspective, this is roughly equivalent to the total biomass of all humans and our livestock.
The researchers broke down the distribution of total avian biomass by orders of birds:
- Passeriformes (perching birds like finches and crows): 29% of total biomass
- Psittaciformes (parrots): 15%
- Charadriiformes (shorebirds and gulls): 12%
- Anseriformes (ducks and geese): 10%
- Galliformes (fowl and gamebirds): 10%
- Procellariiformes (petrels and albatrosses): 7%
- Pelecaniformes (pelicans and allies): 6%
- Sphenisciformes (penguins): 5%
- Gruiformes (cranes and rails): 4%
- Other orders: 2%
The high proportion of parrot and waterfowl biomass reflects the larger body mass of those types of birds compared to the many smaller passerine species that comprise the most numerous bird order. Pelicans, petrels, and penguins also bump up the total biomass relative to their numbers due to being larger-bodied seabirds.
Comparison of Bird Sizes
The range of body sizes in the avian world is incredibly diverse, spanning over three orders of magnitude from the smallest hummingbirds up to the largest ratites and seabirds. This wide variation is illustrated in the table below, which compares weights and dimensions of some of the smallest and largest bird species.
Bird Species | Average Weight | Average Length | Average Wingspan |
---|---|---|---|
Bee Hummingbird | 2 grams | 6 cm | 11 cm |
Ruby-throated Hummingbird | 3 grams | 9 cm | 13 cm |
Andean Condor | 15 kg | 120 cm | 310 cm |
Ostrich | 150 kg | 270 cm | 200 cm |
This comparison shows that even the largest birds are still relatively small compared to many mammalian megafauna. Nevertheless, they occupy an impressive range of body plans and adaptations to take advantage of aerial niches unavailable to other animals.
Largest Extinct Birds
The birds living today give us only a modest glimpse of the enormous size that some ancient avian species attained. Giant terror birds and elephant birds were some of the largest birds ever known, reaching heights over 10 feet and weights up to 1,100 pounds or more. The huge moa, elephant bird egg and giant Haast’s eagle were from a time when birds occupied mammal-like ecological niches prior to human disruption of their ecosystems. These giant extinct birds include:
- Giant moa – up to 12.5 feet tall, 550 pounds
- Elephant bird – up to 10.5 feet tall, 1,100 pounds
- Giant Haast’s eagle – up to 15 pounds with 8-10 foot wingspan
- Terror bird – up to 10 feet tall, 350 pounds
The dodo, at up to 30 pounds, was also much larger than almost all surviving bird species. Humans had a direct role in driving all of these giant bird species extinct through overhunting, habitat destruction and introduction of invasive species. Their massive sizes speak to how big some birds grew in the absence of human pressures.
Wingspans of Largest Flying Birds
While the extinct elephant bird and moa attained much greater heights, today’s largest living flying bird by wingspan is the Wandering Albatross, with an average wingspan around 11 feet. Other seabirds with the longest wingspans are:
- Wandering Albatross – 11 feet
- Southern Royal Albatross – 8.9 feet
- Great Albatross – 8.6 feet
- Grey-headed Albatross – 7.5 feet
- Dalmatian Pelican – 7.5 feet
The albatrosses and pelicans that dominate this list take advantage of long, narrow wings to glide efficiently for hundreds of miles over the oceans. Among land birds, the Andean Condor has the largest wingspan at over 10 feet across. But wingspan alone doesn’t fully illustrate differences in flight capabilities and ecological roles.
Wingspans and Flight Styles
The interaction between wingspan, wing shape, body mass and flying style allows birds to thrive in their respective habitats. For example:
- Small, rounded wings – Maneuverable flight in dense forests. Example: Parrots
- Long, narrow wings – Energy efficient soaring and gliding. Example: Albatrosses
- Broad, slotted wings – Slow flight for scavenging. Example: Vultures
- Pointed wings – Fast transit over long distances. Example: Swallows
So markings like wing tags, GPS trackers and surveys over time will give us further insight into the impressive distances that individual birds cover during their lifetimes.
Flock Sizes of Social Birds
Some birds have evolved to gather together in large flocks for feeding, breeding and migrating. Forming huge aggregations provides safety in numbers and advantages in finding food. Some of the largest flocking bird species include:
- Red-billed Quelea – Flocks up to 10-30 million
- Passenger Pigeon – Historical flocks up to 2-3 billion (now extinct)
- Brown-headed Cowbird – Up to 100,000 around roosts
- European Starling – Up to 1 million around roosts
- Parakeet and Parrot roosts – Up to 30,000
- Murmurations of Starlings – Up to 750,000
It’s astonishing to think that a single flock of Quelea or Passenger Pigeons likely represents a significant fraction of the total global population. The fluid, synchronized movements of huge flocks in flight emerge from the individual behaviors and reactions of birds within the group.
Longevity and Lifespans
In terms of individual lifespans, birds tend to live much longer than their similarly-sized mammalian counterparts. Many birds routinely live through 10-20 years in the wild. Larger parrot species are particularly long-lived, with lifetimes often stretching past 50 or 60 years in captivity. The record for the longest-lived bird ever recorded is an Albatross known as Wisdom, who was still raising chicks at age 67 as of 2017.
Some of the longest-lived wild bird species include:
- Laysan Albatross – Average 50 years, max lifespan 65 years
- Brown Pelicans – Average up to 30 years
- Mute Swan – Average 20 years, max lifespan 30 years
- American Crow – Average 10-15 years, max lifespan 30 years
- Red-tailed Hawk – Average 15 years, max lifespan 30 years
- Macaws – Average 40-50 years in captivity, max lifespan 80-90 years
The extreme long-lived nature of birds like albatrosses allows them to spend years learning complex migratory routes and build lifetime bonds with mates. Their survival capabilities and life history strategies provide insights into aging and population dynamics.
Population and Conservation Status
Although still numbering in the tens of billions worldwide, many bird populations today face serious threats from human activities. Habitat loss, invasive species, poaching and climate change have caused once abundant birds like Passenger Pigeons to go extinct and others such as California Condors to become critically endangered. Population sizes and conservation status ratings for some major birds include:
Species | Population Estimate | Conservation Status |
---|---|---|
African Penguin | 50,000 breeding pairs | Endangered |
Bald Eagle | 250,000 | Least Concern |
California Condor | 490 individuals | Critically Endangered |
Mute Swan | 680,000 | Least Concern |
Whooping Crane | 835 individuals | Endangered |
Targeted conservation programs have helped restore some endangered bird populations like Bald Eagles, but continued habitat protection and funding is vital. Each bird species relies on interconnected ecosystems, so losses cascade through food chains.
Conclusion
Sizing up the vast scale and diversity of the avian world is no easy task, but aiming for quantitative estimates helps reveal their global distribution and significance in nature. Tallying up total numbers, biomass, wingspans and lifespans illustrates the sheer abundance, variation and longevity birds represent on our planet. They occupy every continent, ecosystem, and niche – from tiny hummingbirds sipping nectar to giant albatrosses gliding oceanic distances. Over their long lifetimes, individual birds may traverse incredible journeys spanning thousands of miles. And some species gather in massive superflocks of millions or even billions. While many populations now face severe threats, birds remain one of the most vibrant expressions of the wonders of animal life on Earth.