Information

Why are these nesting magpies building another nest


Pair if eurasian magpies occupy a nest visible from my balcony. It's the nesting season for them here, and I assumed they have laid eggs. I can't see the eggs directly, but one of the magpies has been regularly sitting inside the nest (at least for last two or three weeks) and they always attack other birds that come too close.

Today, they've started building a new nest on another tree. It's pretty close, the nests are about 20 meters apart. They still visit their original nest.

What does it mean? Is it a sign of nesting failure? Does it mean their original nest is no longer sufficient?


I found an article that explains secondary nests as backups in case of nest usurpation by other birds: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4858914/ This is for black sparrowhawks losing nests to Egyptian geese around Cape Town. They measured number of nests built per breeding pair of sparrowhawks and found it to correlate with number of Egyptian geese present and especially their nest usurpation behaviour.

That article mentions brood parasitism (e.g. cuckoos) as another possibility for other birds, and I've seen references to duplicate nests with eggs in each. ( https://www.tandfonline.com/doi/pdf/10.1071/MU939286a )


Birds and their nests

Access to shelter for raising young is pivotal to the persistence of almost all life on earth. Birds are no exception, and they use a remarkable array of types of nests &ndash including burrows (such as spotted pardalotes), stick nests, nests woven from mosses and bark, mud bowls and tree hollows.

Bird nests can be extraordinarily intricate and complex, scrappy, rushed and messy, or neat and minimalistic, or even nonexistent. Birds like masked lapwings, bush stone-curlews, emus, and black-fronted dotterels don&rsquot even bother building nests and lay their eggs directly on the ground, which they may or may not clear before laying. Wedge-tailed eagles, on the other hand, build enormous nests from very large sticks, which they add to each year. These nests can be 3 metres tall and weigh 400 kilograms. It is not uncommon to see zebra finches and other small birds build their nests within these enormous eagle nests, and it is thought that the presence of the eagles can offer them protection from smaller predators.

Figure 1: Emu eggs. Photo Dave Smith

The simple cup nests built by birds like robins, fantails and flycatchers are delicately crafted with birds using their beaks like sewing needles to painstakingly stitch bark fibres and leaves together. Cup nests typically use spider web to bind it together and lash it to a branch - golden-headed cisticolas are sometimes called tailorbirds due to their habit of sewing leaves together with spider webs to conceal their nest. These nests sometimes have outer linings of lichens and mosses for camouflage, and they can look incredibly beautiful. Sometimes cup-shaped nests are slung below a branch rather than sitting on top of a fork - many honeyeater nests are constructed in this way.

Figure 2: Willie wagtail nest - an example of a cup nest. Photo Dave Smith

Figure 3: Striped honeyeater nest - an example of a hanging cup nest. Photo Dave Smith

Figure 4: Grey fantail nest - made from allocasuarina leaves and spider web - an example of a cup nest. Photo Dave Smith

Another common nest structure is the domed nest, which is spherical or bottle-shaped with an entrance on the side. Birds like finches, thornbills, and fairy-wrens build these kinds of nests, and they can be commonly found in dense shrubs. Yellow-rumped thornbills build domed nests with a false cup nest on top of the dome. It&rsquos not entirely clear why they do this &ndash possibly as a means of deterring predators who see the &lsquoempty&rsquo nest and move on.

Figure 5: Striated thornbill nest - dome nest with a side entrance. Photo: Dave Smith

Figure 6: Double-barred finch nest - an example of a dome nest. Photo: Dave Smith

Mud is an excellent material for constructing nests, and several birds use it to build different shaped nests. Magpie larks, white-winged choughs, and apostlebirds build large mud bowls. Welcome swallows build mud nests under rocky overhangs where they can be kept dry. It&rsquos now most common to see these nests under the eaves of buildings, under bridges, or in road-culverts. Fairy-martins build bottle nests from mud, and again these are often seen under built overhangs. Fairy-martins nest in colonies and often attach their nests directly to other nests, sometimes forming large elaborate structures with dozens of nests. Other species, such as pardalotes, sparrows, or even microbats, sometimes use these nests when they are not in use by fairy-martins.

Figure 7: Fairy-martin bottle nests in a rock overhang. If you look carefully you can see smaller mud nests built by mud wasps or potter wasps. Photo: Dave Smith

Waterbirds sometimes build nests on land, and it often surprises people to learn that many duck species nest in tree hollows. Other waterbirds build nests on freshwater islands or in emergent water vegetation on the fringes of waterbodies. Australasian grebes build brilliant floating nests out of buoyant vegetation which they then anchor to the bottom.

Figure 8: Australasian grebe nest - an example of a floating nest. Photo: Suzannah Macbeth

Nest or not?

Not all structures created by birds are nests, and not all things that look like birds&rsquo nests are created by birds. Bowerbirds are a great example here. Males build astonishing structures that they use as displays of their fitness to impress potential mates, but that is not used for nesting. Other birds, such as white-browed babblers, build diurnal roosts, which they use as resting places during the hotter parts of the day. Ringtail possums make dreys to shelter in, and these structures can be mistaken for bird nests.

Using someone else&rsquos nest&hellip

There are even birds that don&rsquot bother to make their own nests &ndash brood parasitic cuckoos instead lay their eggs in the nests of other birds. The eastern koel, channel-billed cuckoo, pallid cuckoo, shining bronze cuckoo, Horsfield&rsquos bronze-cuckoo, and fan-tailed cuckoo are some of the many examples that live in the Murray LLS region. Indeed, it can be bizarre sometimes to see a pair of adults feeding one of their &ldquoyoung&rdquo several times their size &ndash such as adult currawongs feeding a channel-billed cuckoo chick. The image and text message below from a friend show exactly this.

Figure 9: Photo sent in to one of the authors with the message - this bird is currently outside our house, we don&rsquot know exactly what it is (we looked it up and a juvenile sea eagle seemed pretty close), but then we saw a currawong feed it! &ndash it is a young channel-billed cuckoo.

Nesting success

The types of nests that birds use can be a significant factor in their breeding success. One reason is that some kinds of nests are more vulnerable to being predated than others, but this can change depending on the landscape.

Work linked to Sustainable Farms has been carefully examining the factors affecting nesting success. For example, in pine plantation-dominated landscapes, cup or dome-shaped nests are vulnerable to predation. Research in replanted areas on farms showed that such places are important for bird breeding &ndash and nesting success is as high as in native vegetation remnants.

Nevertheless, the nestlings of many Australian birds suffer from very high levels of predation. Some of the culprits, such as ravens and magpies, are to be expected but others are a surprise. The eastern whip bird and even honeyeaters like the eastern spinebill can be nest predators.

Birds have various strategies for dealing with high rates of loss. One is to have multiple clutches in a breeding season. Another is for birds (even very small ones such as thornbills) to live a long time - up to a decade or longer - and over these long lifetimes successfully fledge some of their young.

Tree hollows

Tree hollows are one of the most critical bird breeding resources in agricultural landscapes. Over 300 species of Australian vertebrates depend on tree hollows for sheltering and breeding &ndash including

70 species of native birds. Tree hollows develop mostly in large old trees. Unfortunately, populations of these trees are declining rapidly in many parts of agricultural Australia as a result of fire, clearing of paddock trees, dieback, and a lack of recruitment.

Nest boxes can be a useful way to provide nesting sites for some cavity-dependent bird species, but care is needed to select the &ldquoright&rdquo kinds of boxes to suit the species targeted. That is, match the nest box design to the species. Otherwise, there can be perverse impacts as &ldquoexotic or junk birds&rdquo (that are also agricultural pests) like starlings and Indian/common mynas can benefit. Indeed, nest boxes are generally a poor substitute for large old trees, and the best insights from long-term work are that it is essential to conserve large old trees wherever possible.

Further reading

Belder, D.J., Pierson, J.C., Ikin, K. and Lindenmayer, D.B. (2018). Beyond pattern to process: current themes and future directions for the conservation of woodland birds through restoration plantings. Wildlife Research, 45, 473-489.

Beruldsen, G. 1980. Australian Birds: Their nests and eggs. G. Beruldsen, Kenmore Hills, Queensland.


Introduction

We live in a world dominated by heavily human-impacted ecosystems such as warming oceans polluted by plastic and petrochemicals, and from which marine life has been over-harvested, forests either completely lost or heavily fragmented, rural areas farmed ever more intensively, and rapidly expanding urban areas (Ripple et al. 2017). Of all of these human-transformed environments, arguably it is urban areas that have been transformed most extensively (Johnson and Munshi-South 2017). By 2008, more than half of the world’s human population was living in urban areas (United Nations 2014), with urbanisation continuing globally and rapidly (Seto et al. 2012). Accompanying this burgeoning human population in our towns and cities has been the emergence of the concept of the ‘urban bird’ (e.g., Evans et al. 2011 Marzluff 2014). Although such urban birds may be adapted to urban environments, the urbanisation process profoundly affects the majority of birds because it often involves the irreversible replacement of areas of natural and semi-natural rural habitats such as farmland and woodland with concreted areas of buildings and roads interspersed with gardens, parks and other green spaces (Forman 2014 Shanahan et al. 2014).

While urban birds face many challenges (reviewed in Marzluff 2017) that include exposure to novel predators (López-Flores et al. 2009), food sources (Jones and Reynolds 2008 Reynolds et al. 2017 Jones 2018), habitat types (Rodewald et al. 2013), thermal ranges (Davis et al. 2014a), and stressors such as noise (e.g., Fuller et al. 2007 Sierro et al. 2017), light (e.g., Kempenaers et al. 2010 Dominoni et al. 2013 Holveck et al. 2019) and air pollution (e.g., Isaksson 2015), their expansion and persistence in urban centres offers us many opportunities to understand processes of adaptation to urban living and the development of urban spaces as conservation areas for wildlife more generally. The responses of birds to extrinsic factors in the urban environment play out through processes such as synurbisation (reviewed in Luniak 2004), biotic homogenisation (McKinney 2006 Galbraith et al. 2015 Ibáñez-Álamo et al. 2017a), and ecological traps (Dias 1996 Leston and Rodewald 2006, Sumasgutner et al. 2014a).

It is now rare to attend scientific mainstream ornithological meetings where there is not at least one session devoted to urban birds, and indeed, there are organisations such as the Urban Wildlife Working Group (http://urbanwildlifegroup.org/) that host entire annual conferences devoted to public awareness and management of urban wildlife, including birds. Increasing ornithological interest in urban birds, and especially in their behaviour and ecology, has resulted in the publication of numerous books in this subject area (e.g., Bird et al. 1996 Marzluff et al. 2001 Lepczyk and Warren 2012 Gil and Brumm 2013 Marzluff 2014 Murgui and Hedblom 2017 Jones 2018). Despite this, Reynolds and Deeming (2015) argued that compared with our knowledge of avian life history, behavioural ecology, distribution and abundance, our understanding of the nesting biology of birds is rather limited. This is particularly striking within the urban context. Birkhead (2015) singled out the nesting biology of birds as being fertile ground for future research, even in meeting the primary fundamental scientific aim of obtaining first nest descriptions of most (i.e., an estimated 55% W. Jetz, pers comm) of the world’s avifauna (Reynolds and Deeming 2015). It is shocking that we lack such basic information about extant bird species such nest descriptions will inevitably promote a greater understanding of broader disciplines such as ecology and evolution of birds.

Given that birds invest considerable time and energy in nest building and maintenance (Hansell 2000 Stanley 2002), it is surprising that the nesting biology of birds has been rather neglected as a research focus compared to other aspects of their breeding biology (Deeming and Reynolds 2015a). We now need to go beyond studies that describe how the breeding performance of birds varies with urbanisation (e.g., Tremblay et al. 2003 Partecke et al. 2004 Hedblom and Söderström 2012). As part of this, a focus on investments of time and energy in the location of suitable nest sites and the subsequent construction and maintenance of nest structures would greatly enhance our understanding of the life history and ecology of urban birds (Deeming and Reynolds 2015b). Discussions are currently under way between the authors of this paper and the wider ornithological community about how we can carry out concerted, complementary and meaningful research that is performed in a standardised manner on urban birds at a global scale within urban study sites. Therefore, we have taken this opportunity to write about just one subject area (of many) that we feel has the potential to bring field ornithologists together, whether they are professional or citizen scientists (Greenwood 2007 Dickinson and Bonney 2012 Cooper 2017).

We have chosen to direct the focus of this paper to three different subject areas related to the nesting biology of birds in urban areas. First, we address where urban birds nest, which is essential in making assessments about nest site availability in cities (Kark et al. 2007), allowing subsequent estimation of important measures such as breeding density of study species (Šálek et al. 2015), and heterospecific and conspecific competition (Evans et al. 2009a, 2009b). Secondly, we explore the form of urban nest design allowing quantification of investment in nest construction and maintenance by breeding birds (Mainwaring et al. 2014a) as well as potential relationships between the structure and composition of nests and their fitness-associated consequences for urban birds (e.g., Reid et al. 2002). Thirdly, we discuss to what extent the nesting biology of target species can inform conservation actions and ultimately policy (Collar and Butchart 2014 Deeming and Jarrett 2015). Conserving birds in urban areas may seem to be a low priority for conservationists, given that they inhabit a highly artificial and generally biodiversity-poor environment. However, numerous studies have shown that birds inhabiting urban areas comprise almost all of the interactions that most people living in urban areas have, and that such interactions provide psychological benefits to those people (reviewed in Cox et al. 2017). Such interactions also allow human–wildlife engagement to mediate opportunities for raising conservation awareness. Furthermore, some threatened species have important populations in urban areas (e.g., UK gulls [Laridae]—Raven and Coulson 1997 German Common Swifts [Apus apus]—Schaub et al. 2015), and so we consider that many urban birds are of conservation concern. Finally, we identify key areas for future research that we hope will place the nesting biology of birds at the core of our understanding of how avian species adapt to urban life across the globe (Kark et al. 2007 Croci et al. 2008 Sol et al. 2014).


Behavior

Common Ravens are so bold, playful, and clever that they’re almost always doing something worth watching. They’re less gregarious than crows, often seen alone or in pairs that stay together year round, although many may gather at a carcass or landfill. Large groups of ravens are probably young birds that have yet to pair up ravens begin breeding at ages 2 to 4. On the ground ravens walk confidently, sometimes with a swagger, sometimes sidling. In flight they’re more graceful and agile than crows, which often appear to be swimming across the sky compared to a raven’s light wingbeats and occasional soaring. Ravens often perform aerobatics, including sudden rolls, wing-tucked dives, and playing with objects by dropping and catching them in midair. Known for their intelligence, Common Ravens can work together to solve novel problems. They sometimes follow people and possibly female cowbirds to find nests to raid. (Ravens have followed researchers as they set up artificial nests, raiding them soon after the researchers left.) Young ravens just out of the nest pick up and examine almost anything new they run across as they learn what’s useful and what isn’t. Ravens that find a big food supply (such as a large carcass or unguarded seabird nests) often cache some for later, the way other crows and jays store seeds.Back to top


Pregnant women ‘nest’. But there’s nothing biological about it

is a senior lecturer in ethics at Brighton and Sussex Medical School. Her writing has been published in Prospect and the London Review of Books, among others. She is as an editorial board member of Kohl: Journal for Feminist Research on Gender and the Body and is science editor for the online literary magazine The Offing.

A couple of years ago, a school friend posted online that she’d been deep-cleaning the house while her husband stood by, laughing. She was seven months into her second pregnancy and knew the drill: she was nesting. Social media is replete with accounts of bouts of meticulous cleaning, tidying and decorating as due dates draw closer. The tone is one of amusement, rather than surprise they knew it was coming. Pregnancy manuals and websites make it clear that this compulsion is as natural and irrepressible as pregnancy itself.

Could pregnancy really cause people to clean and tidy? It’s not such an unreasonable suggestion. A new member of the household is on the way, whose needs are urgent and particular, and who will consume the energies of her carers so completely as to rule out much else. It makes sense to get ready while there’s still time, to clean, prepare, baby-proof and perhaps even revamp things a little, to cast out what doesn’t spark joy ahead of a new beginning.

But that’s not quite how ‘nesting’ is presented in pregnancy books and online, which is where most pregnant women get their information. ‘The need to nest can be as real and as powerful an instinct for some humans as it is for our feathered and four-legged friends,’ says the bestselling manual What to Expect When You’re Expecting (5th ed, 2017) by Heidi Murkoff. It goes on:

Pregnancy websites have similar entries, advising that it’s ‘very common to have the overwhelming need to decorate your house, organise your wardrobe and clean everything in sight’, while ‘husbands get yelled at for dropping their socks in the wrong place and the pantry is cleaned and the products alphabetised’. Nesting is depicted not as a set of rational space-preparation activities for expectant parents, but as a set of irrational, hormonally compelled and evolved behaviours, unique to women. No scientific evidence is cited, but it’s assumed that nesting in humans is an analogue of nesting in other animals – birds, mice, rabbits, rats – for whom it is literal: they build physical nests in which their infants will be born and housed.

The catch is, there’s no evidence for biologically mandated nesting in humans. In my research, I found just one study suggesting that women are more likely to clean and tidy during the third trimester of pregnancy. But its findings are based on a questionnaire that asks women to self-report their behaviour, and so its findings are susceptible to taint by women’s own internalised biases. Participants were recruited via pregnancy websites and adverts so the study’s findings might also be compromised by selection bias, since the recruitment method is likely to attract those who are already well-versed in the details of nesting.

I came across two other studies that examined unusual cleaning and tidying due to hormonal changes in the menstrual cycle, rather than pregnancy. Both used small sample sizes and made troubling assumptions but, most worrying of all, their findings are contradictory. One describes nesting across the 14-day luteal phase, the other across the six most fertile days – leading to the implausible conclusion that women are driven to nest for more than half of every month.

There’s no denying that many pregnant women experience nesting: three-quarters of those polled report unusual amounts of cleaning and tidying. But when the evidence base is thin, questionable and contradictory, why do so many websites, books and magazines continue to describe nesting as hormonally determined? The conventional explanation for these culturally specific behaviours (ordering furniture for the nursery, buying toilet rolls, organising linen) dives straight down to the endocrinological level, and from there back to an ancient evolutionary origin. There’s an attractive simplicity to the story: the infants of those mothers who best prepared their living spaces would be most likely to survive, inheriting the genes for ‘nesting’ and passing them on into perpetuity. As one tabloid headline put it: ‘Why pregnant women are obsessed with tidying and nesting: it’s all to do with their inner cavewoman.’

Not only is there no evidence for a hormonal or evolutionary basis for nesting – there are also no studies that demonstrate a mechanism for it. That is, it’s not clear how hormonal changes could bring about shifts in the brain that compel space-preparation activities. And in any event, our understanding of the pressures on early humans is limited. Early humans lived in groups, and survival required cooperation in child-rearing, so it’s not clear that preparing the ‘nest’ would have been solely or even chiefly a pregnant woman’s role. As the philosopher Subrena Smith argues, even if we had more information about the adaptive challenges that our ancestors faced, we couldn’t assume that modern cognitive mechanisms retain the fitness-enhancing functions they once served.

Another sticking point is that human hormones are more complicated than popular discourse would have us believe. It’s long been assumed that testosterone correlates with aggression in human males, as it does in many other animals – but more recent, rigorous analyses show that there’s little relationship between the two. Perhaps the most well-known example of hormones affecting human behaviour is in premenstrual syndrome, in which low mood is reported prior to menstruation. Yet a 2012 review of 47 scientific studies concluded that there’s no clear evidence for a negative mood in the premenstrual phase. Widespread notions of how hormones dictate our behaviour – making men aggressive and women emotional – are not borne out by science. The cognitive scientist Cordelia Fine takes on these myths in her work, most recently in her book Testosterone Rex (2017).

Women do more housework because they’re raised in a world that tells them it’s their place

The biological explanation for nesting has serious social and political consequences. That’s not to say that we shouldn’t investigate the possibility of a biological root, but that we should be mindful of why we’re fixated on that particular kind of explanation. Nesting is not the first instance of women being wedded to gender-stereotypical tasks through some dubious biological link. There have been various attempts to construct and perpetuate a scientific basis for women performing housework by, say, proposing that women must engage in cleaning, laundry and cooking in order to maintain healthy levels of oxytocin, or that women have an innate visual gift for spotting untidiness in their surroundings. There’s no evidence for these myths, and they’ve been firmly debunked.

The uncomfortable reality is that, even outside of pregnancy, women really do carry out more housework than men. A 2015 study of UK parents’ time showed that women spend two to three times as long on housework and carework as men, even when both parents are employed full-time. As a result, married mothers get the least sleep, and men have an additional five hours of leisure time each week compared with women – a gap that has widened over the past 15 years. Importantly, this unjust distribution of housework is sensitive to social norms. Only 7 per cent of people think that mothers should work full-time, while 38 per cent say that part-time work is more appropriate, and a third say they shouldn’t work at all. Even where women’s earnings overtake their male partner’s, men tend to reduce their housework contribution even more, seemingly to protect their masculinity and reassert their expected gender role.

It’s not that women do more housework because of their biological make-up – they do it because they’re raised in a world in which they’re told it’s their place. As progress towards gender equality trundles along in public, the private sphere lags behind, shielded from scrutiny. Most housework is still considered to be ‘women’s work’, and the more repetitive and unrewarding the task, the more gendered the association. Gender stereotyping in relation to housework and carework is still such a troubling issue that in 2019 new rules were introduced in the United Kingdom to ban adverts that perpetuated stereotypes on the grounds that they are ‘likely to cause harm’.

The potential harms of the nesting discourse don’t stop at its unscientific basis or the entrenchment of limiting stereotypes. It’s also worth noting that the ideal that nesting encourages – of a pregnant woman who has a nursery to decorate, excess towels to discard, time to deep-clean the cupboards – is achievable only by a person of some means, who is not monopolised by existing commitments and has been afforded time off paid work prior to the birth of her child. Nesting assumes a home, a (usually male) partner, disposable income, time. As such, it is a very contemporary, middle-class ideal that doesn’t reflect the reality of those who must work until the onset of labour, who are attending to the urgent needs of other dependents, and who have no dedicated space for the new infant.

In light of all this, accepting a hormonal, evolutionary story for nesting requires a leap of faith that isn’t scientific. As the philosopher Lynn Hankinson Nelson points out, we should reach for evolutionary explanations only once we’ve ruled out equally viable alternatives. We will always be limited in what we can know about our distant evolutionary past, and such accounts are therefore especially vulnerable to being warped by our values. ­­­So what are the alternative explanations for ramping up all that cleaning and tidying in the final stages of pregnancy?

First, note that we hold women to higher standards of household tidiness and cleanliness than men, appraising dirty, untidy rooms differently in accordance with the alleged gender of the occupant. These social pressures intensify during pregnancy, when women are under greater social surveillance than at any other time. Further, repetitive tasks such as cleaning and tidying are often used as a coping strategy for regaining control in times of increased anxiety. It’s also worth observing that maternity leave typically doesn’t begin until the third trimester, which is when nesting is reported to kick in. That means women are cleaning and tidying in the window of time between work ending and labour beginning, which looks less like a biological urge and more like pragmatism, or even boredom.

In other words, there’s no shortage of persuasive motivations for intensive space preparation activities in late pregnancy. Nesting starts to look like common sense, or a response to gendered social norms. No biological incentive is needed. The fact that biological explanations appear so attractive has a lot to do with an over-simplistic understanding of gender and sex, in which we attempt to ground the patterns of our complex cultures in biology, where they’re crystallised, entrenched, unchangeable. There’s comfort in this strategy. If housework is hormonally determined, then it isn’t sexist if women do most of it: we can take refuge in the myth that nature made us that way.

The remaining challenge is to tackle the tremendous gendered pressures that women face, particularly in pregnancy and motherhood. Perhaps the only startling compulsion in all of this is the dogged, irrational yearning to root our social world in biology and thereby scupper the path to good science and to justice.


There’s a bird nesting near my house. What should I do?

In general, the best thing you can do for a bird nesting near a human dwelling is to try to minimize the disturbance—stay at a respectful distance, minimize foot traffic, door openings/closings, and postpone and projects or construction slated for the area.

If a bird is nesting in an inconvenient place on your property, the good news is that the nesting period is not forever, and in some species may only be matter of weeks. The nesting cycle for most songbirds, robins included, is around 4 weeks from egg laying to chicks leaving the nest (two weeks of incubation, two weeks of nestlings). Try not to use the area around the nest until the young have fledged to ensure that the parents will not abandon their nest. If this is not possible, try to minimize your presence around the nest many yard birds are tolerant of occasional disturbances.

We don’t recommend that you move the nest Birds will often abandon their nest if it is moved. Only in extreme circumstances should you consider relocating a nest, and if you do, it must be replaced very close, within a few feet of the original location. Once relocated, watch and make sure the parents are returning. If the parents do not return, contact a wildlife rehabilitator.

Some people choose to put up feeders or leave mealworms around to try to provide an additional food source for birds nesting nearby, but this is not necessary for the nest to be successful.

If you are enjoying observing a nearby nest, and would like to go a step further and collect data for science about the nesting behavior, please consider joining NestWatch. All About Birds is an excellent resource for finding out information about birds in general and about incubation and fledging times for individual species.


Magpie Population — How Many Magpies Are Left?

There are estimated to be over 5 million Black-billed magpies living in North America. Their official conservation status is Least Concern. Their population is holding steady though these birds face some threats. For instance, they are considered pests by some farmers because they steal seed and grain from around barnyards. A farmer may put out poison to kill magpies that have invaded their property.

A few magpies in other parts of the world are categorized as Endangered. For example, the Asir magpie’s population is decreasing due to loss of habitat. The Juniper forests in Africa where they live are being cleared.

In addition, the Javan Green magpie is Critically Endangered. The population of this magpie in southeast Asia is decreasing because they are trapped by humans in order to be sold as pets.

Scientists believe there are an estimated 19 million breeding pairs of Eurasian magpies. Their conservation status is Least Concern and their population is stable.

The Australian magpie has a conservation status of Least Concern as well and its population is increasing.


When magpies attack: the swooping, dive-bombing menace – and how to avoid them

H ostilities have broken out up and down the east coast of Australia. The enemy strikes from above, and always attacks from behind. Casualties have been reported and the dive bombings that began with the onset of spring have become more frequent. Zoologists have been called in to devise some means of defence but they have also suffered from the swift and silent enemy.

Yes, from September to November each year in eastern Australia it is magpie madness time and few people, even children, are safe. During nesting, you barely see the black-and-white flash as the magpie turns into a flying missile, swooping down on unsuspecting humans and delivering painful and often dangerous pecks.

A Brisbane newspaper once reported that at one school a fierce magpie had cut the faces of more than a hundred children. Throngs of screaming parents at the school gate were trying to get their terrified children to run quickly across the open spaces to the main building, where a doctor was waiting to provide first aid.

Nick Cilento is familiar with the Brisbane situation and has often been victimised by magpies himself. He decided to investigate their attacks for his honours thesis at Griffith University and spent six months before, during and after an entire magpie breeding season observing their attacks on other humans. He also assisted a team undertaking a survey about magpie attacks that involved 5,000 respondents – the results showed that 96% of men and 75% of women had been victims at some time in their lives.

‘Boys – the usual chuckers of rocks and sticks – in particular becoming prime targets, along with bicycle riders, joggers and posties.’ Photograph: Alamy

Walking adults were rarely attacked but children were, with boys – the usual chuckers of rocks and sticks – in particular becoming prime targets, along with bicycle riders, joggers and posties. Some birds seemed to pick their victims with great care a woman pushing a pram could be attacked even while the magpie ignored boys pelting it with sticks. But Cilento discovered that only about one in 20 mating pairs of birds attacked humans and, of these, only a small number were fiercely aggressive, as if something they had experienced “had turned them into madmen”.

He then set out to draw a magpie’s attention to himself by riding his pushbike through the territory. The attacking bird was typically a male bird, which usually glides silently down from an elevated position so as to approach the intruder from the rear. Sometimes the attack consists of a single swoop, but Cilento was once hit a dozen times on his helmet by the same bird as he pedalled through its territory.

Magpie attacks are always directed at the head. Their weapons of choice are a closed beak or open claws, or they bite and leave two fine cuts where the skin has been pinched and sliced. They also dive bomb, the bird flying fast and using its full body weight to buffet the back of the intruder’s neck or head. This sort of attack can stun and may cause serious bruising.

The magpies’ behaviour follows predictable patterns and individual birds respond to humans according to their own past experience and learning. They are obviously capable of recognising and attacking particular people, which adds credence to the belief in their cognitive abilities. Unfortunately, aggressive magpies represent a serious human–wildlife conflict that is not easily reconciled: “Males get a good response attacking people. They generally don’t hurt themselves and it looks good to the females when they chase this big predator away.”

In the thesis Cilento wrote on his research, he says: “Females seem to understand that humans are a threat only when their fledglings are spending a lot of time on the ground and are vulnerable, which is when the female may become aggressive.”

Also, Cilento says the lack of any references to magpie attacks on humans in Aboriginal mythology suggests the problem is now linked to large numbers of people living in close proximity to each other – and to the magpies. The attacks appear to be simply a response to repetitive stimuli: someone may be bombed on a particular footpath and ignored if they are off it, even if they move closer to the nest.

Worse still, some birds cannot be persuaded to change their ways: one man told Cilento he had been attacked as a boy and the same bird was still dive bombing him 25 years later.

‘Magpie attacks are always directed at the head.’ Photograph: Peter Parks/AFP/Getty Images

For his part, Nick Cilento doubts that the traditional method of removing – that is, shooting – a troublesome bird is the best way of dealing with the problem. He suggests further research be undertaken and for experiments to be done where humans supplement the magpies’ diet by giving them food. Make friends, not war, seems to be the philosophy.

That may be so, and could be worth a try, although some people would argue that the Australian magpie remains the most serious avian menace in the world. In advice to people worried about being attacked by magpies, BirdLife Australia says it is important to remember that magpies are native wildlife, so it is illegal to harm them. It is also important to remember that they only swoop at people for a few weeks during the nesting season – mainly during the period when young birds have just left the nest and are being protected by their parents.

The simplest and best solution is to avoid the area for a few weeks but, if this isn’t practical, another suggestion is to wave a stick above your head, while cyclists sometimes attach stiff plastic strips to their helmets so they project about 10 to 15cm above the head.

If victims have tried these suggestions and they have not worked, BirdLife Australia says local state conservation officers may be able to assist, “though this is at their discretion – and remember, it is illegal to harm magpies”.

This is an edited extract from An Uncertain Future: Australian Birdlife in Danger by Geoffrey Maslen, published by Hardie Grant Books


Why might an orangutan change nests overnight?

Our primate keepers look for behavioral cues—including the proximity of orangutans to one another, as well as the amount of time they choose to spend together—to determine orangutans’ social groups.

Two orangutans that may begin the night in one nest may relocate to a different nest when keepers arrive in the morning. This change in nesting locations is likely the result of social interactions that took place overnight.

Orangutans rarely nest in close proximity to one another of there are any social tensions between individuals, no matter how small. Alternatively, an orangutan may change his or her nest location in order to be closer to another individual.

Bornean orangutan Batang in her nest.


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Lutmerding, J. A. and A. S. Love. (2019). Longevity records of North American birds. Version 1019 Patuxent Wildlife Research Center, Bird Banding Laboratory 2019.

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