What Australian birds can teach us about choosing a partner and making it last



Gisela Kaplan

Gisela Kaplan, University of New England

Love, sex and mate choice are topics that never go out of fashion among humans or, surprisingly, among some Australian birds. For these species, choosing the right partner is a driver of evolution and affects the survival and success of a bird and its offspring.

There is no better place than Australia to observe and study strategies for bird mate choice. Modern parrots and songbirds are Gondwanan creations – they first evolved in Australia and only much later populated the rest of the world.

Here, we’ll examine the sophisticated way some native birds choose a good mate, and make the relationship last.

Rainbow lorikeets form a lifetime bond.
Bobbie Marchant

Single mothers and seasonal flings

For years, research has concentrated on studying birds in which sexual selection may be as simple as males courting females. Males might display extra bright feathers or patterns, perform a special song or dance or, like the bowerbird, build a sophisticated display mound.

In these species, females choose the best mate on the market. But the males do not stick around after mating to raise their brood.




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These reproductive strategies apply only to about tiny proportion of birds worldwide.

Then there are “lovers for a season”, which account for another small percentage of songbirds. Males and females may raise a brood together for one season, then go their separate ways.

These are not real partnerships at all – they’re simply markets for reproduction.

Birds that stick together

But what about the other birds – those that raise offspring in pairs, just as humans often do? Those that form partnerships for more than a season, and in some cases, a lifetime?

More than 90% of birds worldwide fall into this “joint parenting” category – and in Australia, many of them stay together for a long time. Indeed, Australia is a hotspot for these cooperative and long-term affairs.

This staggering figure has no equal in the animal kingdom. Even among mammals, couples are rare; only 5% of all mammals, including humans, pair up and raise kids together.

So how do long-bonding Australian birds choose partners, and what’s their secret to relationship success?

A white headed pigeon pair.
Credit: Gisela Kaplan

Lifelong attachment

The concept of assortative mating is often used to explain how humans form lasting relationships. As the theory goes, we choose mates with similar traits, lifestyle and background to our own.

In native birds that form long-lasting bonds, including butcherbirds, drongos and cockatoos, differences between the sexes are small or non-existent – that is, they are “monomorphic”. Males and females may look alike in size and plumage, or may both sing, build nests and provide equally for offspring.

So, how do they choose each other, if not by colour, song, dance or plumage difference? There’s some research to suggest their choices are based on personality.

Many bird owners and aviculturists would attest that birds have individual personalities. They may, for example, be gentle, tolerant, submissive, aggressive, confident, curious, fearful or sociable.




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Research has not conclusively established which bird personalities are mutually attractive. But so far it seems similarities or familiarity, rather than opposites, attract.

Cockatiel breeders now even use personality assessments similar to those used for show dogs.

There is practical and scientific proof to support this approach. In breeding contexts, seemingly incompatible birds may be forced together. In such cases, they are unlikely to reproduce and may not even interact with each other. For example, research on Gouldian finches has shown that in mismatched pairs, stress hormone levels were elevated over several weeks, which delayed egg laying.

Conversely, well-matched zebra finch pairs have been shown to have greater reproductive success. Well designed experiments have also shown these birds to change human-assigned partners once free to do so, suggesting firm partner preferences.

Zebra finches pair roosting together.
Source Credit: Robyn Burgess

More than just sex

Now to some extraordinary, little-known facets of behaviour in some native birds.

Bird bonds are not always or initially about reproduction. Most cockatoos take five to seven years to mature sexually. Magpies, apostlebirds and white winged choughs can’t seriously think about reproducing until they are five or six years old.

In the interim, they form friendships. Some become childhood sweethearts long before they get “married” and reproduce.

Socially monogamous birds, such as most Australian cockatoos and parrots, pay meticulous attention to each other. They reaffirm bonds by preening, roosting and flying together in search of food and water.

Even not-so-cuddly native songbirds such as magpies or corvids have long term partnerships and fly, feed and roost closely together.

Sulphur-crested cockatoo friends or pair about to land.
Source Robyn Burgess

All in the mind

Bird species that pair up for life, and devote the most time to raising offspring, are generally also the most intelligent (when measured by brain mass relative to body weight).

Such species tend to live for a long time as well – sometimes four times longer than birds of similar weight range in the northern hemisphere.

So why is this? The brain chews up lots of energy and needs the best nutrients. It also needs time to reach full growth. Parental care for a long period, as many Australian birds provide, is the best way to maximise brain development. It requires a strong bond between the parents, and a commitment to raising offspring over the long haul.




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Interestingly, bird and human brains have some similar architecture, and the same range of important neurotransmitters and hormones. Some of these may allow long-term attachments.

Powerful hormones that regulate stress and induce positive emotions are well developed in both humans and birds. These include oxytocin (which plays a part in social recognition and sexual behaviour) and serotonin (which helps regulate and modulate mood, sleep, anxiety, sexuality, and appetite).

The dopamine system also strongly influences the way pair bonds are formed and maintained in primates – including humans – and in birds.

Birds even produce the hormone prolactin, once associated only with mammals. This plays a role in keeping parents sitting on their clutch of eggs, including male birds that share in the brooding.

The power of love

Given the above, one is led to the surprising conclusion that cooperation, and long-term bonds in couples, is as good for birds as it is for humans. The strategy has arguably led both species to becoming the most successful and widely distributed on Earth.

With so many of Australia’s native birds declining in numbers, learning as much as possible about their behaviour, including how they form lasting relationships, is an urgent task.

Much of the information referred to in this article is drawn from Gisela Kaplan’s books Bird Bonds. See also Bird Minds and Tawny FrogmouthThe Conversation

Gisela Kaplan, Emeritus Professor in Animal Behaviour, University of New England

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Turn off the porch light: 6 easy ways to stop light pollution from harming our wildlife



Shutterstock

Emily Fobert, Flinders University; Katherine Dafforn, Macquarie University, and Mariana Mayer-Pinto, UNSW

As winter approaches, marine turtle nesting in the far north of Australia will peak. When these baby turtles hatch at night, they crawl from the sand to the sea, using the relative brightness of the horizon and the natural slope of the beach as their guide.

But when artificial lights outshine the moon and the sea, these hatchlings become disorientated. This leaves them vulnerable to predators, exhaustion and even traffic if they head in the wrong direction.




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Baby turtles are one small part of the larger, often overlooked, story of how light pollution harms wildlife across the land and underwater.

Green Turtle’s Battle For Survival | Planet Earth | BBC Earth.

Today, more than 80% of people – and 99% of North American and European human populations – live under light-polluted skies. We have transformed the night-time environment over substantial portions of the Earth’s surface in a very short time, relative to evolutionary timescales. Most wildlife hasn’t had time to adjust.

In January, Australia released the National Light Pollution Guidelines for Wildlife. These guidelines provide a framework for assessing and managing the impacts of artificial light.

The guidelines also identify practical solutions that can be used globally to manage light pollution, both by managers and practitioners, and by anyone in control of a light switch.




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The guidelines outline six easy steps anyone can follow to minimise light pollution without compromising our own safety.

Although light pollution is a global problem and true darkness is hard to come by, we can all do our part to reduce its impacts on wildlife by changing how we use and think about light at night.

Light pollution can interfere with clownfish reproductive cycle.
Shutterstock

1. Start with natural darkness. Only add light for a specific purpose

Natural darkness should be the default at night. Artificial light should only be used if it’s needed for a specific purpose, and it should only be turned on for the necessary period of time.

This means it’s okay to have your veranda light on to help you find your keys, but the light doesn’t need to stay on all night.

Similarly, indoor lighting can also contribute to light pollution, so turning lights off in empty office buildings at night, or in your home before you go to sleep, is also important.

2. Use smart lighting controls

Advances in smart control technology make it easy to manage how much light you use, and adaptive controls make meeting the goals of Step 1 more feasible.

Investing in smart controls and LED technology means you can remotely manage your lights, set timers or dimmers, activate motion sensor lighting, and even control the colour of the light emitted.

These smart controls should be used to activate artificial light at night only when needed, and to minimise light when not needed.

3. Keep lights close to the ground, directed and shielded

Any light that spills outside the specific area intended to be lit is unnecessary light.

Light spilling upward contributes directly to artificial sky glow – the glow you see over urban areas from cumulative sources of light. Both sky glow and light spilling into adjacent areas on the ground can disrupt wildlife.

Installing light shields allow you to direct the light downward, which significantly reduces sky glow, and to direct the light towards the specific target area. Light shields are recommended for any outdoor lighting installations.

Step 3: Keep lights close to ground (a) and use shields to light only the intended area (b)
National Light Pollution Guidelines for Wildlife Including Marine Turtles, Seabirds and Migratory Shorebirds, Commonwealth of Australia 2020

4. Use the lowest intensity lighting

When deciding how much light you need, consider the intensity of the light produced (lumens), rather than the energy required to make it (watts).

LEDs, for example, are often considered an “environmentally friendly” option because they’re relatively energy efficient. But because of their energy efficiency, LEDs produce between two and five times as much light as incandescent bulbs for the same amount of energy consumption.




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So, while LED lights save energy, the increased intensity of the light can lead to greater impacts on wildlife, if not managed properly.

5. Use non-reflective, dark-coloured surfaces.

Sky glow has been shown to mask lunar light rhythms of wildlife, interfering with the celestial navigation and migration of birds and insects.

Highly polished, shiny, or light-coloured surfaces – such as structures painted white, or polished marble – are good at reflecting light and so contribute more to sky glow than darker, non-reflective surfaces.

Choosing darker coloured paint or materials for outdoor features will help reduce your contribution to light pollution.

6. Use lights with reduced or filtered blue, violet and ultra-violet wavelengths

Wavelength perception in wildlife – most animals are sensitive to short-wavelength (blue/violet) light.
National Light Pollution Guidelines for Wildlife Including Marine Turtles, Seabirds and Migratory Shorebirds, Commonwealth of Australia 2020

Most animals are sensitive to short-wavelength light, which creates blue and violet colours. These short wavelengths are known to suppress melatonin production, which is known to disrupt sleep and interfere with circadian rhythms of many animals, including humans.

Choosing lighting options with little or no short wavelength (400-500 nanometres) violet or blue light will help to avoid unintended harmful effects on wildlife.

For example, compact fluorescent and LED lights have a high amount of short wavelength light, compared low or high-pressure sodium, metal halide, and halogen light sources.




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The Conversation


Emily Fobert, Research Associate, Flinders University; Katherine Dafforn, Senior Lecturer in Environmental Sciences, Macquarie University, and Mariana Mayer-Pinto, Senior Research Associate in marine ecology, UNSW

This article is republished from The Conversation under a Creative Commons license. Read the original article.