Category: Avian Behavior

Mating Monday: Cooperative Breeding

If you missed the previous Mating Monday posts you can check them out here and here.

Cooperative breeding occurs when a mating pair has other birds of the same species helping raise young from one nest. Many time the “helpers-at-the nest” are previous offspring of the parents, but sometimes non-related individuals provide care. This system is widespread throughout the animal kingdom and practiced in approximately 9% of bird species.

“Helpers” play multiple roles. They assist parents with defending the nest and feeding the offspring. A study of Brown-headed Nuthatches (Cusick et al., 2018) found that helpers also removed fecal sacs, but had no part in nest excavation and had no influence on maternal egg production. Cusick et al. concluded that the offspring raised in cooperative groups had more access to food and therefore weighed more. The cooperative nests were also more likely to fledge at least one offspring. Cooperative breeding seems to usually have positive effects for the breeders. But why would an individual forego their opportunity to breed in order to help a nest in which they are not passing on their own genetic material?

There are many factors that influence why cooperative breeding groups exist. One reason may be that environmental constraints limit the opportunities for young birds to breed. Many species that use this system live in regions with low temperature variations and warm winters. This allows the species to become sedentary and establish year-round breeding territories. There may be limited territories due to high-quality habitats being saturated with mature breeders. Low mortality, small clutch sizes, and longevity of offspring contributes to a more stable population that has lower turnover rates, so more birds are available as helpers. Skewed sex-ratios or a shortage of partners (usually females) may also encourage cooperative groups. There are more cooperative breeding groups in altricial species (incapable of moving around on its own shortly after hatching) than precocial (capable of moving on its own shortly after hatching).

Just because cooperative breeding is practiced within a species does not mean that all individuals of the species participate in the system. For example, studies have found that 20-30% of Brown-headed Nuthatches use cooperative breeding as a strategy, with many of the helpers being second-year birds. A study of Long-tailed Tits by Meade & Hatchwell found that helpers had higher overwinter survival rates than non-helpers. Whether or not an individual tit decided to be a helper was determined by the availability of a relative with an active nest. They found that tits that decided to help a relative had a 61% survival rate and the survival rate of those who did not have any relatives with an active nest was 52%. However, male birds that chose not to help a relative with an active nest had a survival rate of 24%. The authors found individuals among the helpers were in good physical condition, the birds without relatives to help were a mix of good/poor condition, and the birds that chose to not help relatives were in poor condition. Meade & Hatchwell also suggested that helping did not have significantly positive effects on reproductive success in the future.

Long-tailed Tit (Image by Alexis Lours via wikimedia commons)

In addition to higher survival rates, helpers may receive other benefits. Helpers may improve their chances of inheriting a mate, territory, or nest. They also gain experience in foraging and may form alliances. Strengthening the genetic makeup of a species through the survival of offspring may be an indirect fitness benefit to the helpers and breeders.

There are many North American bird species that use cooperative breeding. These include Florida Scrub-Jays, Acorn Woodpeckers, Red-cockaded Woodpeckers, Grove-billed Anis, Pygmy Nuthatches, and Gray-breasted Jays.

Brown-headed Nuthatch (Image by DickDaniels via wikimedia commons)

References

Mating Monday: Why Birds Get Divorced

If you missed last week’s Mating Monday on monogamy you can check it out here.

The more I study avian social behavior, the more I realize that humans and birds are not so different after all. Just like in human relationships, sometimes things don’t work out and birds decide to get divorced.

How common is divorce in birds? It’s estimated that divorce occurs in 95% of bird species. Ornithologists describe divorce as when a pair of socially mated birds choose to re-pair with different partners. This can happen after or during the breeding season. There are multiple reasons a bird may want to stay faithful to the same partner. Fidelity has benefits: it helps save energy since time doesn’t have to be wasted finding a new partner. Plus, a familiar pair bond increases cooperation and coordination when raising young. However, when things go wrong there are also many reason why divorce could make more sense than staying together.

It’s common for breeding attempts to fail. Therefore, a pair bond with poor success may find it more beneficial to seek new partners. Mercier et al. states that divorce could be considered an “adaptive mechanism” against having suboptimal partners (2021). A divorcee has the opportunity to find a better mate and possibly more breeding success. Infidelity can also be a reason for avian divorce. Promiscuity in males, but not in females, coincides with divorce rates.

Splitting up doesn’t always have to do with whether or not the nest failed. Sometimes the timing just isn’t right. A study of Eurasian Blue Tits found that 64% of the breeding pairs divorced before the experiment ended, even if the pair had a history of breeding success. Why? If both birds in a pair returned to the breeding territory around the same time they were more likely to stay together, but if the timing was off there was a higher chance of divorce. Since mortality rates are high for many birds, if a mate doesn’t show up “on time” they could be dead or injured. In cases like this fidelity may not pay off. Waiting around could mean losing the chance to breed, so finding a new partner is imperative. Also, studies have found that long-distance migrants such as Arctic Terns have higher divorce rate since unpredictable factors can affect whether or not they return to the breeding grounds on time.

Albatrosses have some of the lowest divorce rates in the avian world. Pairs usually stay together for decades in these long-lived species. However, divorce can still occur and there are some interesting reasons as to why. In Wandering Albatrosses personality can influence divorce. “Shy” males tend to avoid confrontation with bolder males who “intrude” in their territory seeking the female’s attention. As a result the shy bird may give up and desert the relationship. The shy birds were twice as likely to get divorced compared to the aggressive birds.

Black-browed Albatross (left) and Wandering Albatross (right). (Image by Ed Dunens, wikimedia commons)

Environmental factors, such as climate change, may be influencing divorce rates in some albatross species. Ventura et al. studied 15,000 pairs of Black-browed Albatrosses that bred in the Falkland Islands over 15 years. The typical divorce rate of this species is between 1-3%, but in years with unusually warm water temperatures that percentage went as high as 8%. Warm water temperatures means having to travel farther to find food and can trigger stress hormones that leave birds with less energy to raise their chick. Ventura et al. refer to this as the partner-blaming hypothesis. These hormones can lead females to attribute the higher physiological stress to a poor performance by the male. By returning to the breeding grounds exhausted, stressed, and overworked the female may move on to a new partner.

Just for fun I wanted to wrap up this post with some divorce rates: 40-45% in humans, 9% in Mallards, 67% in Piping Plovers, 85% in Emperor Penguins, 99% in flamingos, and 100% in Great Blue Herons. And even swans, which the media likes to have us believe always mate for life, have a 5% divorce rate.

Sweet Mallard Pair (Image by Michelle Horowitz)

References

Mating Monday: Are Most Birds Actually Monogamous?

One of my favorite sights of spring is seeing bird pairs around my yard. Throughout April the cute American Robin pair would take evening walks across the lawn looking for food. The Northern Cardinal pair frequents the feeders together and I even saw the male feed the female some seeds. It’s a common sight to see pair-bonded birds in the spring because many bird species are considered monogamous. In his 1968 book Ecological Adaptations for Breeding in Birds, British ornithologist David Lambert Lack estimated more than 90% of bird species are monogamous.

Black-crowned Night-Herons are presumed to be socially monogamous (Image by David Horowitz)

Merriam-Webster defines monogamy in zoology as “the condition or practice of having a single mate during a period of time”. In 2002, a study by Griffith, Owens, and Thurman found that “extra-pair offspring” occurs in 90% of bird species. If 90% of species are monogamous, how can 90% also have offspring sired by another male who is not in the pair-bond?

Well, it turns out monogamy in birds is a little more complex than a Merriam-Webster dictionary definition. From an evolutionary standpoint, the idea of monogamy occurring in animals at all is a bit of a strange idea. If an individual has the opportunity to mate with multiple partners and doing so can increase their fitness (aka: their reproductive success), then why would they choose monogamy? Biologists are learning that when it comes to animals, three types of monogamy come into play: social, sexual, and genetic. Lack’s assertion that 90% of species are monogamous refers to social monogamy. This means that bird pairs work together to raise offspring, but there is no guarantee that they are sexually or genetically monogamous. In fact, the Griffith et al. (2002) study contributes to the idea that genetic monogamy (that the two partners only have offspring with one another) is quite rare in birds. True genetic monogamy does occur in some species, such as Common Loons, Dovekies, Florida Scrub-Jays, and some populations of Red Crossbills. However, at least some females in about 90% of bird species will mate with a male who is outside of her pair bond, a behavior called extra-pair copulation.

Why would a female seek out a mate outside of her social bond? First, her social mate may have genes that are inferior, so mating with a more desirable male can allow a female to pass on better genes to her offspring. Secondly, a female is more likely to get her eggs, which are a limited resource, fertilized just in case her social mate is infertile or incompatible. Lastly, extra-pair copulation allows a female to have genetically diverse offspring by multiple fathers. It’s the “don’t put all your eggs in one basket” idea.

Some Mourning Doves stay together for one breeding season and others may mate for life (Image by Michelle Horowitz)

So yes, a vast majority of bird species are monogamous, but it’s not as clear cut as it seems. Many of our cute little bird pairs have something going on “on the side”. Many birds will only stay together for once breeding season and find a new mate the next. There are some species that do mate for life, but that’s not as common as we once thought.

Infidelity, divorce, and even same-sex pair bonds (although rare) occur in birds. And what about the other 10% of birds that don’t practice monogamy? What mating system do they use? Over the next few weeks we’ll explore some of these interesting avian behaviors on Mating Monday. Stay tuned!

Book Review: Red-Tails in Love

A person usually becomes well-acquainted with the natural cycles and rhythms of a specific location if they spend many years observing nature there. But one of the great joys of birdwatching is to expect the unexpected. In the mid-1990s, nobody in New York City ever expected to find a pair of Red-tailed Hawks setting up a nest on the façade of an apartment building on Fifth Avenue and 74th Street, but it happened. Marie Winn chronicles the amazing journey of the “Fifth Avenue Hawks” in her delightful book Red-Tails in Love.

Central Park was designed in 1858 by Frederick Law Olmsted, who is widely considered the father of landscape architecture, and his partner Calvert Vaux. Olmsted and Vaux wanted to create a bucolic escape from the hustle and bustle of urban life, but never intended the park to become the wilderness that it is today. Over 280 bird species have been recorded in Central Park since it’s inception. Red-tailed Hawks started breeding near the park in 1994 with the hawks described in Winn’s book and continue to breed there to this day.

Winn discovers The Bird Register, a notebook used by Central Park birdwatchers to share their sightings with one another. She quickly becomes a willing student of many of the park’s most frequent and experienced birders who she dubs “The Regulars”. Winn shares the stories of The Regulars while giving us a glimpse into the park’s annual nature cycles such as spring migration and fall hawk counts.

But one day the smooth flow of normal birding was interrupted when a distinctive male Red-tailed Hawk appeared. Unlike a typical Red-tail, this individual was exceptionally light, missing the trademark brown “belly-band” and having an almost white head. The Regulars dubbed him “Pale Male” and he unknowingly became the star of his own romantic drama. When Pale Male and his new mate, nicknamed “First Love”, attempted nesting on the apartment building hawk watching become an obsession.

Winn briefly takes us through 4 years of breeding attempts. Like any good romantic drama (if Red-tails were the movie stars lol) there’s stunning displays of affection, failed nesting attempts, and of course adorable chicks. There’s even a case of mistaken identity and the rallying of the troops with US Fish & Wildlife to protect the nest. One of my favorite parts was Winn describing the hawk watchers on their bench giving the hawks encouraging remarks like “Great job mom!” to the female feeding her chicks and “Wow, nice catch dad!” when Pale Male arrives to the nest with a rat or pigeon.

Bird watching is already an amazing pastime, but it’s extra special when you get the rare opportunity to know an individual wild bird. For the Central Park birders Pale Male wasn’t just some Red-tailed Hawk; they knew him personally. He had daily routines, favorite locations, and a family. They worried about the hawks’ well-being, protected them at all costs, and celebrated their accomplishments. The “Fifth Avenue Hawks” not only fostered the Central Park birding community, but became an integral part of it. The hawks helped citizens connect, created friendships, and encouraged people to become stewards of the natural world in their own backyards. Marie Winn reminds us through her wonderful story that we can all be part of that community; all we have to do is enjoy nature with an open heart.

When living at the Jersey Shore we had our own “Pale Male”, an American Oystercatcher called “T2”. You can read about the Jersey Shore’s most beloved oystercatcher here, here, and my love letter to him here.

References

The Gull and the Shark

I found a fun sequence while looking through old Barnegat Light pictures: a second year Great Black-backed Gull getting ready to eat a small dead shark. Gulls are omnivores and will pretty much eat anything, including small sharks. Just type “daring seagull eats live baby shark” into YouTube if you want to watch a gull in action. The bird on the right in the two top pictures is a Herring Gull. The captions are what I imagine they were saying to each other :-).

“A shark?…Looks like a treat!”
Herring Gull: ” Hey Black-backed, you gonna eat that?”
“Of course I’m gonna eat it!”
“This shark is mine! ALL MINE!”

Birds and Light Pollution

Happy World Migratory Bird Day! I hope you are able to get out and enjoy watching the birds today. The 2022 theme for World Migratory Bird Day is light pollution.

Many bird species migrate at night, so light pollution from populated areas disorients their navigation, disturbs their internal clocks, and cause numerous collisions every year. In the United States alone, 100 millions birds die annually from collisions with buildings. Building collisions can happen during the day too, but the lights at night add an extra threat by attracting birds to the area, in the same way that your porch light attracts moths.

A study published in the journal Nature in 2020 found that light pollution is starting to impact breeding habits of some birds species as well. The researchers analyzed how noise and light pollution impacted breeding success of 58,506 nests from 142 North American species. They found that light pollution leads species of open habitats such as grasslands to breed up to a month earlier and 18 days earlier in forested environments. In forested habitats noise pollution was more disruptive than for open habitat birds, causing some species to delay breeding. These changes in breeding habits can cause temporal mismatch which could lead to higher mortality rates due to weather events and difficulties finding food sources.

Bird Mortality from Collisions (Bishop, 2018)

According to the World Migratory Bird Day website, artificial light is increasing by 2% each year globally. While that may not seem that much, this increase is having adverse effects not only on birds, but other species including humans. There are 4 components to light pollution: glare (excessive uncomfortable brightness), clutter (bright confusing groupings), skyglow (brightening of the night sky in inhabited areas), and light trespassing (light in unwanted or not intended areas). According to the International Dark-Sky Association, 80% of the global population lives under skyglow and up to 99% of the public in Europe and the United States can’t experience natural night! Industrial civilization is the root cause of light pollution. Light pollution also affects melatonin production, discombobulates circadian rhythms, disrupts ecosystems, and increases energy consumption.

Lights Outs is a program created by the National Audubon Society to combat light pollution. The program encourages building managers and owners to turn off excess lighting during migration season to make it easier for birds to travel. Lights Out has found success in many cities throughout the United States and is becoming more popular over time. Individuals can participate in Lights Out events too.

So what can be done to help birds and reduce light pollution? Here are some simple steps you can take:

  • Turn off unnecessary lights. Only use lighting if needed.
  • Set lights on a timer or motion detector
  • Keep blinds closed to keep light inside.
  • Participate in citizen science projects to measure light pollution such as Globe at Night , Cities at Night, or track on your smartphone using apps such as The Dark Sky Meter app. Check out the “Measuring Light Pollution” page at The Dark-Sky Association website for more information to get involved.
  • Support programs such as Lights Out
  • Spread the word about light pollution to you friends and family. Knowledge is power!

References

Book Review: Baby Birds

Baby Birds: An Artist Looks Into the Nest by Julie Zickefoose is a fantastic account on how baby birds develop in the nest, as well as a beautiful work of art. From 2002-2015, nature artist Julie Zickefoose set out to learn how baby birds develop and depict the amazing process through watercolors. In 13 years she painted 17 different songbird species. Many of the nests she found in her own backyard, an 80-acre sanctuary called Indigo Hill in Ohio. Some species were sent to her in pictures by friends who found interesting bird species in their yards.

Baby Birds: An Artist Looks in the Nest by Julie Zickefoose

From the day the young hatched, Zickefoose would select a chick (usually the oldest) and bring it into her art studio to paint. She would repeat the process each day of the nestling’s life until it seemed like it was ready to fledge. In certain instances Julie was able to continue to observe the birds after they fledged. Each species she encountered offered a unique and many times surprising experience. Zickefoose’s journey was not without its challenges though. She was not opposed to interfering when she felt it was needed. She rehabilitated some chicks, dealt with nest parasites, and warded off predators in order to help with their survival (although a few times these efforts did not pay off).

There are two types of baby birds: precocial and altricial. Precocial birds are born more developed, usually with down feathers and the ability to walk on their own. They are able to leave the nest within hours of hatching and can find food for themselves. Waterfowl, galliformes, and shorebirds are precocial. Altricial birds are underdeveloped upon hatching and require care from the parents for an extended period of time in order to survive. Examples of altricial birds include raptors, pigeons, and passerines (perching/songbirds). Julia focuses strictly on altricial birds in order to closely track their development.

The tone of Baby Birds is very casual; much of the book reads as if you are reading directly out of Zickefoose’s journal (which is some cases you are). Each species account begins with a spread of Julie’s painting with her fields notes. In a glance you can see what the bird looked like as it developed. As you dive into the chapters, Zickefoose breaks down what occurred each day and what milestones the chick reached. Next to each day is a larger version of the painting you see on the beginning spread.

I really enjoyed Julie’s style. The illustrations/paintings are very detailed and beautiful. She really captures the essence of each chick and the paintings look life-like. Peppered throughout her personal experiences are interesting facts about the species that she learned from research. Some species that Zickefoose painted include Eastern Bluebird, Carolina Wren, Chimney Swift, Ruby-throated Hummingbird, Indigo Bunting, and the only cavity-nesting warbler, the Prothonotary Warbler. My favorite was the Yellow-billed Cuckoo.

I found it interesting that Julie included 3 species that many people consider pests: the House Sparrow, European Starling, and House Wren. Although she was originally against letting these birds nest and would remove any nests of these species she could find, sometimes the birds had other plans. She did ended up appreciating the experience to learn about these birds that people usually shun. In her chapter about House Sparrows, Julie notes that in some of their natural range of Eurasia, these sparrows are rapidly declining. It’s interesting that people in the sparrow’s natural range are scrambling to try to save their beloved bird, while people in the United States want them eradicated for stealing nesting spaces from native birds. In regards to this idea Zickefoose remarks, “Take no bird for granted, no matter how abundant.” It’s a sentiment that I agree with. Each individual bird is important, especially today in the midst of climate change and a rapidly changing world.

I would recommend Baby Birds to anyone with a love for nature, birds and/or art. Julie Zickefoose cleverly mixes art, science, and her personal experiences to captivate her audience and leads us on a fascinating journey into the life of baby birds.

Old Friends

At the end of March, Dave and I visited Cape May Point State Park and South Cape May Meadows for some early spring birding. There were still a lot of winter visitors around, but many spring migrants were starting to arrive.

First of season (year) species during this trip included Ospreys, Field Sparrows, Common Grackles, Greater Yellowlegs, Great Egrets, Eastern Phoebes, Tree Swallows, and my favorite: the American Oystercatchers.

The beach of South Cape May Meadows is where we ran into one of our old friends: Oystercatcher 38. We met 38 last year at the same location, but according to his account from the American Oystercatcher Working Group, 38 is about 8 years old.

American Oystercatcher 38 (Image by BirdNation)

This year 38 was with an unbanded Oystercatcher that could potentially be its mate. They were running around the beach together.

38 with its potential mate (Image by BirdNation)

At one point, 38, his mate, and another pair engaged in a courtship display. During a courtship display, pairs will stretch their necks forward and down with their back parallel to the ground. They will run side-by-side with their mate will making pip! notes and bobbing their heads. Occasionally the pair will fly up in the air while piping. Many times pairs from other territories will join in on the display. When multiple pairs display together it is referred to as a “Piping Tournament” or “Piping Ceremony”. It was fun to see our friend 38 again. Below is a video of their piping tournament.

American Oystercatcher Piping Tournament (Video by BirdNation)

If you ever see a banded oystercatcher I would recommend submitting your sightings to the American Oystercatcher Working Group. They are a great organization, and their website contains a wealth of information about the American Oystercatcher’s life history, behavior, and banding. Check out their website at http://amoywg.org/

Timberdoodle!

Spring is almost here, and we are certainly getting signs of the coming season in New Jersey. The weather is finally starting to warm up a bit, and I’ve been hearing American Robins start their bouncy spring songs each morning. The spring migrants are returning, and that includes a very fascinating and unique species…the Timberdoole!

Well, the Timberdoodle is its nickname (and an awfully cute one at that). I’m referring to the American Woodcock, a small bulbous shorebird that migrates through New Jersey in March.

I heard about these birds pretty early into my life as a birder, but never have had the chance to see them because…I would forget. I would be so busy in the spring that I would remember about the timberdoodle after it already passed through the area. I knew this year would be different.

Dave and I went to Rancocas Nature Center (where I’m a teacher naturalist on some weekends) to watch the display. The meadow at RNC is a great place to check out the Timberdoodle. The Timberdoodle is not just a bird you simply go to just get a sight of, the allure of this little bird is the famous “Sky Dance”.

American Woodcock (Image via Pinterest)

Timberdoodles like to spend their time in brushy fields near deciduous forests. In the cover of darkness, the male Timberdoole will give a distinct buzzy “peent!” to get the female’s attention. After a few calls, the male rockets up into the air with a flutter, soaring up and circling about 200-300 feet in the air. As the male ascends into his dazzling display you can hear his wings twitter. After reaching his peak, the male circles back down to the ground and land in the same spot next to the female. These aerial display can last into the night and take place around dawn as well. Once a pair does mate, the male provides no parental care. Males usually mate with multiple females. The female will feed the chicks for a week, and about a month later the chicks will become independent.

It was really amazing to see the American Woodcock’s sky dance. We observed at least 4 birds participating in the display. We even had a pair fly right over us! I’m so glad we had a chance to observe these magnificent birds in action.

I was able to get a short recording of the “peents” at the beginning of the display (I was too mesmerized watching to record anything after it start lol). You can hear a few peents through the wall of sound that is a bunch Spring Peeper frogs calling.

American Woodcock “peents!” with Spring Peeper background

Have you seen a Timberdoodle? Tell me about your experience in the comments!

Love Birds…or not?

You’ve probably seen an image like this before, especially around Valentine’s Day:

Mute Swans forming a “heart” with their heads. The perfect image of love. Or is it? It’s not as simple as you might think.

When you see a bird with its mate, you might assume that those birds are just mates with each other. Sometimes that’s true, the bird pair you’re watching may be monogamous. However, there is actually a wide variety of avian mating systems, so things are usually not as they seem on the surface.

Wood Duck pair (Image by BirdNation)

3 main types of avian mating systems include social monogamy, polyandry, and polygyny. These systems can be broken down even further, with multiple categories for each system. We aren’t going to go too far into specifics today, but here’s a quick overview of some of the avian mating systems.

Social Monogamy

In social monogamy, one female will form a pair bond with one male. This doesn’t necessarily mean that the pair is mated for life. The pair bond may last only one or several breeding seasons. In the social monogamy system, females may copulate with other males. This means within a clutch of chicks, some chicks may have different fathers. About 92% of bird species are considered monogamous, but it’s actually quite rare to find species that practice true genetic monogamy. Genetic monogamous species only have offspring that are within the specific male/female couple.

Common birds that practice social monogamy include Northern Cardinals, Eastern Bluebirds, Black Vultures, and Mute Swans. Examples of genetic monogamous birds include Common Loons, Laysan Albatrosses, and Florida Scrub Jays.

Northern Cardinal male (Image by BirdNation)
Common Loon on land (Image by BirdNation)

Polyandry

In polyandry, during a breeding season a female will accept sperm from multiple males. There are many reasons why a female would want to have sperm from multiple male partners. A female bird’s oviduct has a special sperm storage tubules (SSTs) where sperm can be stored for days to weeks depending on the species. Eggs are only able to be fertilized for a certain period of time. Therefore, by storing sperm, a female would be able to fertilize a clutch of eggs and not have to mate at a particular time to be able to do so. Females who practice polyandry can use this system as a sort of “insurance policy”; a female is more likely to be able to fertilize eggs if one of her partner’s sperm are defective if she mated with multiple males. Other reasons for polyandry include securing more parental care/resources/genetic benefits from secondary partners, or being forced to copulate by sexually aggressive “partners”.

This mating type is only found in about 1% of bird species. Examples of polyandry in bird species include Spotted Sandpipers, Sanderlings , and Wilsons Phalaropes.

Spotted Sandpiper (Image by David Horowitz)
Sanderling (Image by BirdNation)

Polygyny

In polygyny, males are able to have sexual access to two or more females, however a female will only mate with one male. Males of this mating systems may defend valuable resources that will attract several mates as well as try to monopolize potential mates against rival males. Males may also defend a specific territory and try to convince females to visit and mate with him. This tactic is called lek polygyny. Some males in a lek may not mate with any females, while only a few males will mate with most of the females.

Many grassland birds practice polygyny. Examples include Red-winged Blackbirds, Great Sage Grouse, Bobolinks, and Marsh Wrens.

Red-winged Blackbird, Taylor’s Wildlife Preserve (Image by BirdNation)


And if this all wasn’t complicated enough…

…sometimes birds get divorced. Yep, you read that right. Sometimes the breeding season is unsuccessful and each member of the pair will choose to mate with someone else. Sometimes a partner dies and the widow finds a new mate. Whatever the reason, it just goes to show that avian lives are much more complex than we previously knew or imagined.

So what about those Mute Swans we were talking about earlier? Divorce can rarely occur between Mute Swans, but they are generally monogamous. They do tend to form strong pair bonds and work together well as a team. Does that mean Mute Swans are an accurate depiction of true love? Maybe. Or maybe not…you be the judge. It does prove though that the avian social life is complex and fascinating.