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Archive for March, 2016

For millions of years, since they evolved from the dinosaurs, birds have done just fine without any human intervention or assistance. No human-provided bird houses, bird baths or bird feeders. Not only have birds survived without us, they prospered. Year after year they have continued to raise new generations. They evolved and adapted to bad weather and changes to their environment. They don’t need us.

When early European settlers first arrived in the new world they were surprised to see a few Native American tribes hanging hollowed-out gourds from trees around their villages hoping that birds would nest in them. The first bird houses. This was not an altruistic effort to help the local birds survive. Rather, they were trying to attract birds to their village. Living closer to nature than modern villagers, Native Americans noticed that certain species of birds consumed lots and lots of flying bugs and insects. They reasoned if they provided good nesting sites maybe more of these beneficial birds would be attracted to their neighborhood. More birds would eat more pesky insects and life would be better.

Settlers emulated the native’s practice and adapted it for their homesteads. Over time the practice of hanging a bird house in your backyard that began for a practical reason now morphed into the need for a cute little bird house in every suburban backyard. Even though most of the species that utilize these cute houses do not devour enormous quantities of pesky bugs. Today the main purpose of a backyard bird house is for entertainment, and as a modest way to reconnect with nature and be environmentally correct. It is also wonderful education experience for youngsters.     

A House is Not a Home

The popularity of bird houses has led to some common questions and misconceptions. The first misconception is that a bird house is a home. It isn’t. Birds don’t actually live in a bird house. Birds use a bird house for only one purpose – to build a nest, lay eggs and make sure their kids grow up healthy. Once the kids are old enough to leave home and live on their own, the bird house is abandoned. That’s it. They no longer use it. Ornithologists, for years, have tried to promote the term “nesting box” instead of “bird house” but it has never caught on with the public even though it is technically accurate. I think a more descriptive term might be a “bird nursery” but I doubt that term will catch on either.

What Makes a Good House?

Choosing a new bird house or nesting box always raises questions. What features should you look for? Which design is best? A cutesy design will have what a realtor would call curb appeal. But that appeal is intended for the human landlords. Birds do not really care what it looks like. They are primarily looking for shelter and safety for their family.

There are a few key elements to consider in selecting the ideal house. The first is the construction material. Wood is good. Avoid metal houses which can become dangerously warm and oven-like on hot, sunny days. Quality construction techniques ensure long life. Choose a house that is assembled with screws instead of glue, nails or staples. It will last much longer. The design of the house should provide some ventilation allowing hot air to escape on warm days. A roof that projects beyond the entrance hole provides some protection preventing rain from entering and creating a soggy nest. An easily accessible “clean-out” hole should allow removal of the old nest at the end of the year.

And, finally, my pet peeve in bird house design – the perch. Get rid of it. Sure, the classic image of a cutesy bird house includes a proud parent sitting on the perch about to enter the house. But birds do not need it. A perch just gives a potential predatory something to hold onto while it reaching into the entrance hole to grab an egg or nestling. So, no perch.

What Kind of Tenants

Shopping for a bird house in a nature store can be confusing. There are a variety of houses available.   One might be labelled as a bluebird house. A sign on the house next to it may identify a chickadee house. Birds can’t read. So how does a chickadee know which is the correct one to use? The answer is simple. It is all about the size of the circular entrance hole. Chickadees are small birds. So the chickadee house has a very small hole. A chickadee can enter easily through the small opening, but a larger bird such as a bluebird or a starling is too large to fit. Of course, any bird smaller in size than a chickadee would also fit through the small entrance hole. Or the opposite can happen. A small chickadee might use a house with a larger hole. In fact, a larger hole makes the house accessible to a wider variety and size of birds.   You never can be sure who will move in. Hopefully someone will.

What Kind of Tenants

Not every species of bird will use a bird house. A robin won’t use a house, nor will a mockingbird or a hummingbird. They build their nests on branches. The types of birds that use a human-provided house are known as cavity nesters. In the wild, they build their in any cavity they find – a hole caused by lightning strike or decay, a broken limb or an old woodpecker hole. A bird house simulates a natural cavity.

No Vacancy

Occasionally a family will hang a house in their backyard but no birds actually use it. How can you insure that a bird will use a house? You can’t. Birds, like people, can be finicky. I know. My wife and I must have looked at over a hundred houses before she found one she liked. You may hang up the absolutely loveliest bird house, and the birds will build their nest on the lamppost next to it.

My uncle, a successful realtor, always believed that advertising was essential to attracting the greatest number of potential new tenants.   He created this ad for our house.  It can’t hurt.

For Rent

  • Lovely One Bedroom Apartment
  • Clean and Spacious
  • Nice Neighborhood
  • Good Landlord
  • Ideal for Growing Family

 

To Clean or Not to Clean

Once the nestlings have fledged and the family has left the house what should you do? It hangs there unused but full of old sticks, grasses and stuff. Should you clean it out and get it ready for new tenants next year? For years the recommended practice has been to clean out the house each fall. There is concern that some parasites remaining in the old nest might survive the cold winter and would be harmful next spring when the new fledglings and young and vulnerable. However, recently some bright young ornithologist realized that in the wild bird use natural cavities.  No one cleans out the old remnants from those nests in natural cavities. Yet birds have survived for millions of years. So maybe a cleaning is not absolutely necessary.

Birds are not dependent on human-provided housing for survival. However, the need for human housing grows and cities expand. Formerly undeveloped land is being destroyed to make room for housing developments and shopping malls. As a result, the number of natural cavities available is shrinking. A bird house provides a ready substitute.

You may want to consider becoming a housing developer or landlord by putting a second house in your backyard. Mortgage rates are low. And birds need housing. So put up a bird house, nesting box or bird nursery. If you hang it they will come.

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My favorite bird-related question, although it is not in a top ten FAQS, is “how long do birds live?” It is my favorite because the answer is not a simple number. The answer depends. Moreover, it depends on many different factors. And that gives me the opportunity to explain why it depends.

Living Conditions

One major factor influencing the life expectancy of a bird is its living conditions. A bird living in captivity, say in a zoo or aviary, will outlive the same species living in the wild. In captivity it is safe from predators, sheltered from the environment, receives nutritious food on regular basis without having to hunt for it, and may even receive medical attention when needed. Life in the wild is considerably tougher.

In a similar way, human life expectancy is also highly dependent on living conditions. People living in first world countries tend to outlive those in third world countries, war torn areas or drought regions. They live under better conditions, have better sanitation, access to better nutrition and medical care with fewer mortal perils. So it is not surprising that a captive bird will outlive its wild cousin. A bird in your backyard that may regularly live for 8 years in the wild, could live an additional 4 or 5 years in captivity. It might be a duller life, but it will be longer. So when we reference life expectancy number, it helps to know if it is based on a wild or captive birds.

A bird’s life expectancy also depends on how you define the term. Sadly, most birds do not live to be one year old. The first year is tough on youngsters. Some studies show that the first month may be the most deadly. They are not experienced in finding food or shelter and have not learned to avoid predators. The majority, more than 50% die in infancy or adolescence. If you include all these infant mortalities when calculating the average life span of a species, the resulting number would be depressing low. However, once a bird survives the first year, it can expect a longer life. If you take all the early deaths into consideration you might say the average robin lives less than two year. However, if you only consider those robins that have survive adolescence, they may have a remaining life expectancy of 5-8 years.

A bird’s life span also depends on various factors. Bigger birds tends to live longer than smaller birds.   Tropical species survive better than temperate zone species and seabirds survive better than land birds.

Bigger is Better

A typical sparrow-size bird might live 4-6 years. A slightly larger bird, such as a robin, may live an additional 2-3 years.   Crow-size birds live even longer. Hawks, eagles, swans and other large birds may live 20-25 years. Parrots are legendary for outliving their owners. In general, bigger is better.

Old Time Stories

The Guinness Book of Animal Records credits a Siberian white crane as having the longest recorded lifespan at 82 years, although this record is not well documented.

Wisdom

Some long lives are well documented. Albatross are among the largest birds with wingspans of over 11 feet. So it is not surprising that currently the oldest known living bird is a female Laysan Albatross named Wisdom. She is at least 63 years old, maybe older. We can be reasonable certain of her age. Chandler Robbins, a well-known wildlife biologist with the US Geological Survey, banded her on Midway Atoll, a remote island in the Pacific Ocean, in December 1956. Although we are not sure how old she was at that time, it was estimated that she was maybe 4-5 years old. Robbins captured Wisdom again over 40 years later. And other scientists continue to observe her regularly. Her ID band has been replaced five times.Albatross - Wisdom

Albatross return annually to their home island to bred, laying a single egg. In Feburary 2014, Wisdom returned again to Midway Atoll at the age of 63. Even more remarkable than her advanced age, she laid and incubated her single egg raising yet another albatross chick. That also puts her in the ranks of the oldest mothers in the animal world. Imagine how many children, grand-children, great grand-children, and great-great, grand-children would be in Wisdom’s family photograph.

The USGS estimates that in her lifetime Wisdom has flown more than 3 million miles, the equivalent of over 5 round trips to the moon.

Another story that illustrates the longevity of larger birds involves von Humboldt’s parrot. Alexander von Humboldt was a Prussian-born naturalist, explorer and promoter. In the early 1800s he led expeditions to unexplored regions of the Amazon jungle. On one journey he stumbled upon a never-before-seen native tribe, called the Atures, in a remote area of the jungle. The tribe was previously unknown and isolated, not only from the outside world, but even from neighboring tribes. Obviously they had never seen a European before. The tribe had its own unique verbal language, but no written language. Despite the communication difficulties Von Humboldt and the tribal chief hit it off. When it became time for the expedition to move on, the chief gave Von Humboldt his pet parrot which was fluent in the tribal language.

Unfortunately, the explorers may have passed on a fatal disease to the natives and within a few years the entire tribe eventually died off. As a result their unique verbal language was lost to the world. Except for the parrot which, by default, then became the only being in the world to speak their language. After returning to Germany, Von Humboldt, emulating PT Barnum, toured Europe for several years promoting the oddities he discovered on his Amazon expeditions including the only parrot in the world who could speak an extinct language. Audiences were fascinated.

Fred

In the late 1970s Robert Blake starred in popular television detective series called Beretta. His character, Tony Baretta, had a pet sulphur-crested cockatoo named Fred. This species is known for longevity and there are reports on the internet that claim Fred lived to ripe old age of 83. This can’t be verify because in the 1990 Fred was kidnapped (or birdnapped) from the San Diego Wildlife Park where he had been performing.

Maximum vs. Average Lifespan

A long life for one individual does not mean other individuals of that species will live just as long. Recent news reports covered the birthday party for the oldest living man in the US who was turning 105. Yet the average life expectancy of all men is closer to 70 years. Extremes happen but are not representative of the whole.

For example, Stamford University reported on 1746 Purple Finches that were captured, banded and released to the wild and then recaptured again. 1731 of the recaptured finches had initially been banded sometime during the previous 6 years. Only one of the recaptured individuals had been banded over 10 years earlier. So how would you define the life span of these finches? 10 years? Or 6 years?

Large birds do live longer lives. At the opposite extreme are the small birds. Tiny hummingbirds do have a much shorter lifespan than an albatross, but not extremely short. The average hummingbird may live 3-5 years. The record for a ruby-throated hummingbird in the wild is 6 years, 11 months. In its long life this tiny bird weighing less than a dime made 14 migrations trips of 2000 miles or more. The longest lived hummingbird was a larger Broad-tail hummingbird that lived 12 years in the wild.

If someone asks you how long a bird lives, remember the answer is “it depends.” Are they asking about the maximum lifespan, the average lifespan, in captivity or in the wild, big bird or little birds? The answer depends and the factors that impact longevity make interest trivia.

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