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Ornithology with Lab, Quarter 3

Welcome to Quarter 3! Do you need to go back to Quarter 1? Quarter 2? Go forward to Quarter 4?

Day 91

1. We’re going to go over a few more birds from Madagascar before we move on. Watch the video about wetland birds from Madagascar.
2. Watch the video about the helmet vanga.
3. Watch the video about the coua family.
4. Print the third quarter grading sheet and save this paper for later.

Day 92

1. Let’s move on to the Oriental realm (aka the Indomalayan)! Containing India, southeast Asia (Malay Archipelago), Java, Borneo, and the Philippines. This region contains about 2,400 bird species, but has very few endemic species. In fact, only two bird families, Irenidae and Chloropseidae, are endemic to the Oriental realm. (These families were formerly classified as one, Irenidae.)
2. Look at the range map and photo for Chloropseidae (leafbirds).
3. Watch the video of the golden-fronted leafbird.
4. Look at the range map and photo for Irenidae (fairy-bluebirds).
5. Watch the video of the fairy-bluebird.

Day 93

1. Southeast Asia has many, many islands. The Malay archipelago is only about twice the size of Alaska, but it has over 20,000 islands! Most of the birds that are endemic to the Indomalayan are limited to a single island or island chain.
2. We talked about Wallace’s Line previously (the imaginary line that divides the Indomalayan region from the Australasian.) Take a look at this map to see the area of overlap between Australasian and Indomalayan species.
3. Take a look at the birds of Malaysia.

Day 94

1. The Australasian realm includes Australia, New Zealand, Papua New Guinea, and nearby islands. There are about 1600 species of birds in the Australasian regions, over 900 in Australia alone, but these birds occupy very little of the continent. About 70% of Australia is desert, and only 17 bird species are found there. That means that most of the diversity occurs in 30% of the land area.
2. To see one of the 17 species occupying Australia’s desert interior, watch “The Wild Bush Budgie.”

Day 95

1. Australasia is home to three of the five living ratite families – emus, kiwi, and cassowaries.
2. Watch the video “This Cassowary Can Kill You.”
3. Watch the video about Emu Facts.
4. Watch the video taking a closer look at the kiwi.
5. Continue your bird count! (If you are using the paper version and yours is full, you can print another copy of the tally sheet on day 5.) Go outside and count all birds you see or hear for 15 minutes. Try to identify the birds and count how many of each you notice. Save your count sheet (or if you are using the app, be sure you are logged in so your count will be saved.)

Day 96

1. Today watch “The Cassowary: The Last Living Dinosaur.”

Day 97

1. Let’s continue looking at birds endemic to the Australasian realm! Watch the video about the lyrebird.
2. Watch footage of the superb bird-of-paradise and the king bird-of-paradise.
3. Watch the video about the bowerbird.

Day 98

1. Today we’re looking at more birds endemic to Australasia. Watch the video of the apostlebird. Then watch the video with facts about it.
2. Watch the video about honeyeaters.
3. Watch the video of megapodes laying their eggs in warm volcanic ash.

Day 99


Before the arrival of humans about 700-800 years ago, there were no terrestrial mammals on New Zealand (and just three species of bats). At that time, the avifauna of New Zealand included at least 245 species and, of these, 59 are now extinct. In the absence of mammals, birds dominated the New Zealand ecosystem. That changed with the arrival of Polynesian Maori settlers. Many species of birds were hunted by these settlers, including moas, shags, parakeets, penguins, pigeons, petrels, ducks, rails, and kiwis (McGlone 1989). As is also the case for many islands in the Pacific, this hunting, along with habitat degradation and introduction of non-native species by the Polynesians that preyed on birds and their eggs led to the extinction of several species. Among the extinct species are the moas, South Island Adzebill (Aptornis defossor), New Zealand Raven ( Corvus antipodum), Waitaha Penguin ( Megadyptes waitaha), Scarlett’s Shearwater (Puffinus spelaeus), Grey-headed Blackbird (Turdus poliocephalus), the world’s largest eagle (Haast’s Eagle, Harpagornis moorei; about 12 kg and a wingspan up to 3 m), and many more.

2. Watch the video about keas.

Day 100
1. Today we’re watching another documentary! Watch the video about the kakapo, the heaviest parrot in the world.
2. Continue your bird count! (If you are using the paper version and yours is full, you can print another copy of the tally sheet on day 5.) Go outside and count all birds you see or hear for 15 minutes. Try to identify the birds and count how many of each you notice. Save your count sheet (or if you are using the app, be sure you are logged in so your count will be saved.)

Day 101

1. The final realm we are going to cover is the Antarctic realm. The continent of Antarctica is mostly covered in sheets of glacial ice, but during the summer, some areas (mostly coastal) melt and expose some ice-free land. These ice-free areas support breeding populations of penguins, petrels, and other sea birds.
2. Watch the video about birds of Antarctica and sub-Antarctic islands.
3. Watch the video “17 Penguin Types in One Video.”

Day 102

1. Today watch the documentary about South Georgia Island.

Day 103*

1. Now we are going to transition to the food and feeding habits of birds.

Because of their high metabolic rates, birds must consume more food in proportion to their size than most animals. For example, a warbler might eat 80 percent of its body weight in a day. As a group, birds consume just about any type of food you can imagine, including amphibians, ants, buds, carrion, crustaceans, fish, fruit, grass, insects, larvae, leaves, mollusks, nectar, other birds, pollen, reptiles, rodents, roots, sap, seeds, suet, snails, wax, & worms. Birds acquire these food items in a wide variety of ways.

2. Look at the diagram. These are the major foraging “guilds” of birds. Vertivores prey primarily on vertebrates and invertivores on invertebrates, granivores are primarily seed eaters, frugivores feed primarily on fruit, scavengers feed on carrion, nectarivores primarily on nectar, herbivores on plants, and aquatic predators on a wide variety of aquatic prey.
3. Print page 1 of the PDF and complete the crossword puzzle.
4. Check your answers and record your score out of 9.

Day 104

1. Watch the video about animal foraging behavior. (Foraging is not specific to birds, all animals need to have a strategy for finding and acquiring food.)
2. Watch the video about birds’ trophic guilds.
3. There are numerous specific niches when it comes to the ways birds collect their food. Look at the diagram of foraging niches used by land based insectivores. Then look at the diagram showing foraging niches used by aquatic predators.

Day 105

1. Birds with different diets have beaks or bills that are shaped differently. These specialized shapes allow them to access their preferred food. Watch the beginner’s guide to bird beaks.
2. A bird’s bill is made of a bony framework covered by a tough layer of keratin, which is continuously replaced and worn down throughout the bird’s life. Birds use their bills for various things, including preening, singing, regulating their temperature, building nests, using tools, and getting food. Bills act as versatile, tweezer-like clamps for most birds, with relatively weak bites. However, some birds have high biting force, such as parrots and other seed-eating birds, as well as birds that frequently kill prey with their bills, such as falcons and shrikes.
3. Continue your bird count! (If you are using the paper version and yours is full, you can print another copy of the tally sheet on day 5.) Go outside and count all birds you see or hear for 15 minutes. Try to identify the birds and count how many of each you notice. Save your count sheet (or if you are using the app, be sure you are logged in so your count will be saved.)

Day 106

1. Watch “How Birds got and Kept Their Beaks.”
2. Watch the video “Weird Beak Shapes: and Why They Make Sense.
3. Play the “What’s for Dinner?” game. Look at the bird beaks to match them to the correct food. Play more than once – you will get different birds each time.

Day 107*

1. Study the variations in bill morphology. Be sure to match the descriptions to the pictures, and try to remember how different shapes are associated with different feeding habits.
2. Watch the video “Bird Feeding Adaptations.”
3. Print page 1 and page 2 of the worksheet. Match the bird beaks to the foods they eat, and answer the questions.
4. Record your score out of 14 (1 point for matching, 1 point for answering the questions for each bird.)

Day 108

1. Another way of classifying birds is by the habitat or type of place where they gather food. The following are the most general categories:

  • aerial (in the air)
  • ground (on the ground)
  • arboreal (in trees)
  • aquatic (in or around the water)

Aerial and ground food collection is mostly self explanatory.
2. Watch the video of swallows drinking water mid-flight. (Swallows are aerial insectivores.) Typically they use their wide mouths and precise flying skills to capture insects in the air.
3. Many different bird species feed on the ground. Watch the video of ring-necked pheasants foraging on the ground.
Tomorrow we will learn more about specific arboreal habitats where birds gather food.

Day 109*

1. Print page 1 of the PDF and identify whether the paths the birds take to find food is aerial, ground, arboreal, or aquatic. Check your answers and record your score out of 13.
2. Read about the difference between aerial, terrestrial, and arboreal birds.
3. Categories of arboreal foraging include:

  • bark (woodpeckers)
  • floral (hummingbirds)
  • canopy (toucans, macaws)
  • undergrowth (thrashers, warblers)
  • foliage (chickadees)

Because of overlap between habitats, feeding patterns, and behaviors, it can be difficult to cleanly categorize a specific bird into one foraging guild, and some birds may belong to multiple guilds.

Day 110*

1. There is a wide variety of niches that birds that forage in and around water can find their food. These include:
Coastal (Along Ocean Coasts):

  • coastal beach
  • coast bottom
  • coastal rock
  • coastal water surface


  • freshwater marshes
  • freshwater bottom
  • freshwater shoreline
  • freshwater surface

Pelagic (Open Ocean)
Riparian (River):

  • bottom
  • shoreline

2. Watch the video about pelagic birds.
3. Watch the video about riparian areas and why they are important.
4. Print page 1 of the PDF and complete the puzzle. Check your answers and record your score out of 8.
5. Continue your bird count! (If you are using the paper version and yours is full, you can print another copy of the tally sheet on day 5.) Go outside and count all birds you see or hear for 15 minutes. Try to identify the birds and count how many of each you notice. Save your count sheet (or if you are using the app, be sure you are logged in so your count will be saved.)

Day 111

1. Moving on: we will be studying the various techniques used by birds when foraging. The ways birds find and collect food varies greatly, from chasing prey to cracking open seeds. Today we will look at variations of ambush and stalking behaviors in birds.
2. Some species of herons use a technique called baiting, in which they will drop small objects onto the water’s surface and wait for fish to come investigate. In the wild, they may use small feathers. Watch this video about a heron at a hotel that used bread to attract and catch fish.
3. Watch this video of an egret using a behavior called ‘foot stirring.’ (You can guess why it’s called that!) Foot stirring is a technique used by wading birds to startle small prey out of hiding places so that they can be eaten.
4. Watch another video of foot stirring. This behavior is also sometimes called foot trembling, foot raking, or foot scraping.

Day 112

1. Let’s continue our exploration of the strategies birds use to collect their food! Today we are starting with chasing. Chasing is when a bird pursues prey on the ground, typically by running to catch it. One example of a bird that chases its prey is the roadrunner. Watch the video of a roadrunner facing off with a snake. Then, watch this video to see a roadrunner actually catch something. (You can restart and watch the whole video if you like, but I’ve cued it up to just before it makes a catch.) Chasing birds may also leap to catch prey with jumps propelled by powerful leg muscles.
2. Another technique birds use to find food is called scratching. You will be familiar with this technique if you have ever watched chickens for very long! Scratching birds will remove a layer of ground cover or soil with their claws in order to uncover food below. Watch the video of chickens scratching in a pile of leaves. By scratching, birds can uncover small invertebrates to eat, small rocks to swallow to help them grind up food, and also create places to dust bathe.

Day 113

1. In birds that hunt aquatic prey, there is a technique used called plunging, in which the bird plunges from the air into the water and captures prey with its mouth. A variation is foot plunging, in which the birds plunge into the water and capture their prey with their feet. When the entire body of the bird goes underwater to catch its prey, this behavior is called diving.
2. Watch the video of the osprey plunging to catch fish with its talons.
3. Watch the video of a Caspian tern plunging to catch fish.
4. Watch the video of gannets diving.
5. What’s the difference between plunging, foot plunging, and diving? Can you recognize it when you see it?

Day 114

1. Take a look at this chart showing the difference between different seabird feeding strategies.
2. Penguins use a tactic called underwater pursuit. Watch the video about penguins diving for food in the Antarctic.
3. Other birds use a technique called surface seizing. They sit on the surface of the water and eat whatever food might be floating there. Watch the video of albatross and petrels feeding with this technique.
4. Still other birds flutter just above the surface until they find prey. Watch the ring-billed gulls fluttering above the surface to pick out prey.

Day 115

1. Today we’re going to take a look at a feeding behavior called dabbling. Ducks are the most well-known birds that feed by dabbling, but other waterfowl such as geese and swans will do it as well. In dabbling, a bird will dip its entire head or neck – not just the bill – under water.
2. Watch the video of mallard ducks feeding.
3. Watch the video of Canada geese dabbling. As you can see, you can recognize this feeding behavior easily because the tail end of the bird will go up while the head goes underwater.

Day 116
4. Continue your bird count! (If you are using the paper version and yours is full, you can print another copy of the tally sheet on day 5.) Go outside and count all birds you see or hear for 15 minutes. Try to identify the birds and count how many of each you notice. Save your count sheet (or if you are using the app, be sure you are logged in so your count will be saved.)

1. Some birds use a foraging strategy called excavating. Arboreal birds search for food by drilling holes in the bark and wood of trees. The most famous example of a bird that uses an excavating strategy is the woodpecker. Woodpeckers may also excavate holes to use for nesting.
2. Watch the video of a pileated woodpecker excavating.
3. Watch the video about how woodpeckers can excavate without causing brain damage. (You can stop when they get to the part about the book at the end.)
4. Watch the video about acorn woodpeckers. Intstead of looking for bugs, these little birds excavate holes in trees to store food.

Day 117

1. One feeding technique sometimes observed in birds is called piracy (or, more formally, kleptoparasitism). This occurs when birds steal food from animals, other birds, or humans.
2. Watch the peregrine falcon attempt to steal from an osprey.
3. Watch the video of a corvid stealing food from skunks in a zoo. Note how it pulls and pecks on their tails to get them to move so it can access the food better.
4. Watch the video of seagulls stealing a sandwich.

Day 118

1. Another bird feeding strategy is called gleaning. Gleaning is a way birds feed themselves by catching small animals, especially bugs and insects. They grab these creatures from different places such as plants, the ground, or tiny spaces like between rocks or under roofs. Sometimes, they also get these creatures from living animals, like ticks and lice.
2. Watch the video of the bay-breasted warbler gleaning in a tree.
3. Watch the video of starlings gleaning for insects on the ground.
4. Watch the video of the yellow-billed oxpecker gleaning parasites from a water buffalo.

Day 119

1. Probing is a feeding strategy that involves inserting the beak into the ground or another surface and using touch to find food.
2. Read the article about probing.
3. Watch the video about sandpipers gathering shrimp while being hunted.

Day 120

1. Another feeding strategy used by birds in and around the water is called straining. Birds that strain their food use special structures in their bills to separate food from mud or water. Read the article about how flamingos filter food from the water using lamellae in their bills.
2. Watch the video of the northern shoveler straining food from the water. You can see that these ducks use multiple feeding strategies, including dabbling, which we covered earlier.
3. Read the article “What’s the Deal with Duck Bills?” to see close-up pictures of duck lamellae and answer the question “do ducks have teeth?” (Hint: no.)
4. Continue your bird count! (If you are using the paper version and yours is full, you can print another copy of the tally sheet on day 5.) Go outside and count all birds you see or hear for 15 minutes. Try to identify the birds and count how many of each you notice. Save your count sheet (or if you are using the app, be sure you are logged in so your count will be saved.)

Day 121

1. Scavenging is another feeding strategy used by birds, in which they eat carrion or dead animals. The most famous scavenging birds are vultures, although many more types of birds will scavenge on occation.
2. Watch the video about how vultures evolved to eat carrion.

Day 122

1. Finally, we are going to look at birds that catch bugs in the air. There are a few names for this behavior: hawking, flycatching, and screening. Each term refers to a different bug-catching strategy.
2. Hawking is when birds catch flying insects in the air. Watch the video of sand martins hawing mayflies.
3. Screening refers to a strategy where the bird flies along with its mouth wide open, like a net, and catches bugs directly with its mouth. Birds that practice this strategy can typically open their mouths very wide. One bird that practices this strategy is the nighthawk.
4. Watch the video of the nighthawk darting around to screen insects from the air.
5. Look how big its mouth is!
6. Flycatching, on the other hand, is a strategy where birds wait on a perch and then dart out into the air to catch insects. They will return to their perch to eat the bug.
7. Watch the grey wagtail flycatching. Note how it sits on a perch until prey appears. Then it will dart into the air to catch the bug, and return to the same perch.

Day 123

1. Today, watch a documentary- Hunters of the Sky: Europe’s Birds of Prey.

Day 124

1. Now we’re going to talk about territories. A “territory” means an area that a bird protects. This can be any place, even just where they build their nest. Most birds defend some areas at least part of the year. The benefit of protecting their territory is that they can get more resources or better resources than they would without protecting it. There are different types of territories based on what the bird is protecting, such as food or nesting areas.
Type A – mating, nesting, and feeding territory: This is an all-purpose territory where the bird performs all its activities like mating, nesting, foraging, and courtship. Many songbirds defend this type of territory.
Type B – mating and nesting territory: This territory is where all the breeding activities take place, but most foraging occurs outside the territory. Both males and females can forage outside the territory, and the size of the territory varies from location to location.
Type C – nesting territory: This type of territory is a small area around the nest.
Type D – pairing and mating territory: This territory is defended by males in lekking species, where they pair up with females and mate.
Type E – roosting territory: This territory is where birds rest or roost.
Type F – winter territory: This territory is used by birds during the winter season, which includes foraging and roosting areas. It can be equivalent to the Type A territory or located on the wintering grounds for migratory birds.
2. Watch the video of songbirds defending their territories.

Day 125

1. Territorial defense requires time and energy and may even pose a risk of injury or death. These are the “costs” of defending a territory. However, the “benefits” of defending a territory include improved access to resources such as food, nest sites, or roost sites. Birds will only defend their territories if the benefits of defense are greater than the costs, which is known as “economic defendability.” When resources are very scarce or unpredictable, the cost of defense would likely exceed the benefits. When resources are abundant, the defense is unnecessary because there is plenty for everyone. However, when resources are at a moderate level, territorial defense can increase the amount of available resources, which can lead to a small energy “profit” for the bird. For example, in a study of Golden-winged Sunbirds, when there was high nectar levels, the cost of defense likely exceeded the benefits, but when there were low nectar levels, territorial defense led to a significant reduction in daily foraging time.
2. Watch the video “Hummingbird Battleground.”
3. Watch the video “Woodpeckers Defend Their Food Supply.”
4. Continue your bird count! (If you are using the paper version and yours is full, you can print another copy of the tally sheet on day 5.) Go outside and count all birds you see or hear for 15 minutes. Try to identify the birds and count how many of each you notice. Save your count sheet (or if you are using the app, be sure you are logged in so your count will be saved.)

Day 126

1. Sometimes birds defend a specific territory only when they are breeding, often for access to important resources needed for successful reproduction, such as food and nesting sites. The quality of a male’s territory can impact his reproductive success. For example, male dickcissels with territories that have greater vegetation density may be able to attract more mates compared to males with lower quality territories. Having a high-quality territory is associated with better breeding success, such as producing more offspring.
2. Watch the video of a male dickcissel singing. Singing is one way that males defend their territory. By singing loudly and well, a the male bird lets others of his species know that he is healthy, strong, and ready to fight. Singing can also be used to attract a mate, for the same reasons.
3. Watch the video “Why do birds sing so darn early?
4. Watch the video about hidden movements in migratory birds.

Day 127

1. So how do birds defend their territories? There are multiple methods that might be used. Read the article about bird territories. Pay attention to the following territorial defense methods.

  • Singing
  • Displays
  • Aggression and Chasing
  • Marking

2. We already talked about how birds use singing to mark their territory. A strong, complex song usually means a healthy male. It’s one way for them to tell rivals, “Don’t mess with me.”
3. Sometimes, instead, male birds will display to attract a mate and intimidate other males. Watch the sage grouse displaying. Of course, one of the most famous examples of birds displaying is the peacock. Watch the peacock display his tail feathers.
4. Aggression and chasing may seem like the most obvious way that birds defend their territories. Pecking, clawing, and beating rivals or threats with their wings is a sure way to chase them off. One example of birds that aggressively defend territory is blue jays. Watch this video of a blue jay chasing a cardinal away from a bird feeder.
5. Finally, some birds mark their territory with urine or feces. We will not watch a video for that one.

Day 128

1. British biologist Julian Huxley proposed in 1934 that bird territories could be compared to rubber discs that get smaller when they are compressed. This means that as the population of birds in an area increases, the territories become smaller. However, territories can only become so small before they are not large enough to support the birds in them. Therefore, there is a limit to the number of possible territories in an area. If there are too many birds, there may be some birds without territories.
2. Jerram Brown suggested in 1969 that at higher population densities, birds may be excluded from high-quality habitats and forced to occupy lower quality habitats. At even higher densities, birds may be forced to occupy unsuitable habitats, which could lead to a decrease in population size. Steven Fretwell suggested in 1972 that birds may choose to occupy poorer habitats if high-quality habitats are already occupied by other birds.
3. For many species, Brown’s model may be the best explanation for the impact of territorial behavior on population size. For example, a population of Song Sparrows on an island off the coast of British Columbia has been studied for several years. Male Song Sparrows are territorial, but there isn’t enough space for all of them to have a territory. Non-territorial males are called floaters and do not breed. The number of floaters increases as the number of territorial males increases.
4. As the number of breeding females increases, the number of successfully fledged young per female declines. This could be due to decreased brood size or decreased success in raising young due to food limitation. Additionally, the proportion of juveniles surviving also declines as the total adult population during the fall season increases. This could be because food limitation causes females to provide smaller amounts of food to each nestling, so they are fledged at a smaller average size.
5. Watch the video of a sparrow defending resources (food) from other birds.

Day 129*

1. Different bird species have different strategies for reproduction, which can be influenced by their habitat, location, and lifespan. One of the factors that affect the number of eggs a bird lays in one nest, called the clutch size, is how long the bird is expected to live. Birds that live for a shorter amount of time tend to lay more eggs in each nest, while birds that live longer tend to lay fewer eggs.
2. This is because birds have limited time, energy, and resources, and they have to balance these resources between laying eggs and taking care of themselves to avoid predators and other dangers. So, birds with shorter lifespans need to maximize their reproductive success in each breeding attempt to ensure that their genes are passed on, while birds with longer lifespans have more time to invest in each offspring and can spread their reproductive efforts out over time.
3. To illustrate this idea, think of an albatross that can live up to 40 years. They start breeding when they are 10 years old, versus a chickadee that can live up to 7 years and start breeding when they are 1 year old. The albatross has more time to breed over its lifetime, so it doesn’t need to lay as many eggs in each nest. On the other hand, the chickadee has fewer breeding seasons in its lifetime, so it needs to lay more eggs in each nest to maximize its reproductive success.
4. Overall, there are many factors that influence the number of eggs that birds lay in each nest, and scientists are still trying to understand how natural selection has shaped these different reproductive strategies.
5. Print page 1 of the PDF and use the reading above to answer the questions. Check your answers and record your score out of 6.

Day 130

1. Scientists have noticed that some animals have different success with reproducing depending on how old they are. There are three ideas that could explain why this happens.

  1. The first is that it’s based on the animal’s experience with reproducing at different ages.
  2. The second is that it’s based on the animal’s effort to reproduce at different ages.
  3. The third is that it’s based on the animal’s ability to survive and produce offspring as it gets older.

Scientists studied a type of bird called Leach’s storm-petrels to test these three ideas. They wanted to know if there was a connection between how successful the birds were at breeding when they were young and how long they lived. The three ideas predicted different things: no connection, a negative connection, or a positive connection. The scientists found that there was a positive connection between early breeding success and longevity. This means that birds that were good at having babies early on were also more likely to live longer. This supports the idea that animals with low productivity (or less success at having babies) are also less likely to survive when they’re young.
2. Watch the video about reproductive success in animals.
3. Continue your bird count! (If you are using the paper version and yours is full, you can print another copy of the tally sheet on day 5.) Go outside and count all birds you see or hear for 15 minutes. Try to identify the birds and count how many of each you notice. Save your count sheet (or if you are using the app, be sure you are logged in so your count will be saved.)

Day 131

1. The size of a bird’s clutch (the number of eggs laid in one nest) can be affected by different factors. One of these factors is the location where the bird lives. Birds living in tropical areas tend to have smaller clutches than those in colder areas. Some people think that this is because there is not enough food or because there are more predators in the tropics.
2. One scientist, Alexander Skutch, thought that predators were forcing bird parents to limit their visits to the nest and, therefore, resulting in smaller families. However, this idea had not been tested until Thomas Martin and his team did so by monitoring nests in Argentina and Arizona. They found that the Skutch theory was true in some cases, but not in others. In Argentina, where predators were less of a problem, the birds still had smaller clutch sizes. The scientists suggest that other factors may be involved, such as the parent’s mortality rates in different climates. In addition to predators and food supply, other factors like seasonality, pathogens, and environmental unpredictability can contribute to smaller clutch sizes in tropical birds. These different factors can impact different physiological systems that ultimately result in small clutch sizes and long lifespans in tropical birds.
3. Watch the video about eggs. What are some of the factors they mention that influence how many eggs a bird would lay?

Day 132

1. In order for the chicks inside their eggs to develop, birds need to incubate them, or keep them warm. The best temperature for eggs seems to be 37-38 C (98-100 F). If the eggs are exposed to temperatures that are too high or too low, it can be lethal or slow down the development of the embryo.
2. Heat is transferred from the bird’s body to the eggs through specialized areas of bare skin on the abdomen and/or breast called brood patches. Before incubation begins, the skin in the area of the brood patch loses its feathers to aid in heat transfer. Almost all bird species temporarily lose their feathers on specific areas of their breast or abdomen early in the breeding season to develop these brood patches. This bare skin helps transfer body heat for incubating the eggs and brooding the chicks. The feathers are replaced in a complete molt that follows the breeding season.
3. Watch the video about how birds incubate their eggs.

Day 133

1. Birds need to incubate their eggs to keep them warm and help them develop properly. This can take a lot of energy, especially when the temperature is not warm enough. Researchers found that when female Great Tits had more eggs to incubate, they used more energy to keep them warm during the night. However, reducing the number of eggs did not lower their energy use. This may be because there is a limit to how many eggs can be in contact with the bird’s brood patch, which is where the heat comes from. If there are too many eggs, the bird has to spend extra energy to keep rearranging them to keep them warm. Birds with thicker nests needed less energy to keep their eggs warm, but building thicker nests takes more energy too. This information helps researchers understand how birds make decisions about how many eggs to lay and incubate.

Most birds sit on their eggs to incubate, but there are exceptions. For example, male Emperor and King penguins place their egg on their feet, and incubate it while standing up. The egg is kept warm by the heat from the male’s feet and stomach. Megapodes, found in Southeast Asia and Australia, use heat sources such as geothermal, solar, or decomposition of organic material.

3. Watch the video about emperor penguins huddling to keep their eggs warm.

Day 134

1. Malleefowl birds spend most of the year, about 9 to 11 months, making a big mound out of soil, leaves, and twigs. The female lays her eggs in the mound and then they are buried. The heat from the composting pile of leaves and twigs incubates the eggs. These mounds can be used by many generations of Malleefowl birds and can get as big as 22 meters around and one meter high. The birds use their beaks to measure the temperature of the mound and make adjustments to keep it around 32-34 degrees Celsius. Incubating the eggs usually takes around 60-90 days. Look at the diagram of a malleefowl nest under construction.
2. Another bird with a similar strategy is the Australian brush turkey. Male Australian Brush-Turkeys try to keep the temperature around 34°C when they make nests for their eggs. They do this by using dry litter and making sure there is not too much water in the nest because it loses heat faster when it’s wet. The turkeys visit their nests every day for about 0.5 to 2 hours and add or remove vegetation as needed to keep the temperature right. Although the average temperature is usually around 34°C, it can change a lot, especially when it rains. But unlike other birds, the Brush-Turkey’s babies can handle these changes and still grow up healthy.
3. Watch the video about the nest of the Australian Brush-Turkey.

Day 135

1. Most birds transfer heat to their eggs using a special patch of skin called a brood patch. However, some birds, such as the Nazca booby, hold their eggs under the webs of their feet. (As we’ve already discussed, some species of penguins also incubate their eggs on their feet.) The feet are between the eggs and the feathery body of the bird, making it unclear if heat for the eggs comes from the feet or the body. Studies have shown that boobies that are incubating eggs have more blood flow to their feet than birds that are not incubating eggs, meaning that probably some extra body heat is being transferred to the eggs directly through the feet.
2. Watch the video about incubating booby eggs. You can see the way the bird covers the eggs with its feet.
3. Continue your bird count! (If you are using the paper version and yours is full, you can print another copy of the tally sheet on day 5.) Go outside and count all birds you see or hear for 15 minutes. Try to identify the birds and count how many of each you notice. Save your count sheet (or if you are using the app, be sure you are logged in so your count will be saved.)

Please proceed to Quarter 4!