Interesting foraging behavior observation in juncos

When I first started this blog, I mentioned that I would write about natural history observations from my fieldwork. I have written natural history-ish things, mostly about hummingbirds or describing hikes I have done, but here is a true natural history observation I made while doing fieldwork back in Arizona that I was thinking about recently. The main character in this observation is the yellow-eyed junco (Junco phaeonotus):

An adult yellow-eyed junco.

Now these are actually yellow-eyed juncos, not the red-backed dark-eyed junco morph, which looks like the yellow-eyed (look at the eye color for confirmation). The location of this story is Mount Lemon, just outside of Tucson, Arizona, in the Santa Catalina Mountains. I was up around 7000 feet (2134 meters) near the Rose Canyon Campground and Rose Canyon Lake. Yellow-eyed juncos like to hang out in pine-oak or other coniferous forests, that are fairly open, like the one I was in, so they were quite common and easy to observe there.

Juncos are in the new world sparrow family Passerellidae and, in my opinion, are some of the more interestingly colored sparrows. This species, as many in the family, primarily feeds on seeds and insects while foraging on the ground. And my observation focuses on an interesting foraging behavior I observed.

A juvenile yellow-eyed junco foraging.

I was in the area looking for broad-tailed hummingbirds to help a documentary crew film their breeding and courtship behavior. As a note, there were also a ton of broad-tailed hummingbirds in this area. I arrived several days before the crew showed up, which gave me the opportunity to explore the area a bit – mostly scouting for hummingbirds. I was sitting on a tree stump, after a bout of hummingbird scouting, and I saw some of these juncos feeding on grass seeds along the road. I do not know what species of grass they were feeding on, but the seeds were on the top of the long, thin grass stalks.

A view of the thin, tall grass along the roadside with a junco foraging.

Given that these grass stalks were too thin and weak to support a perched bird, I figured the juncos were either hopping up to grab seeds mid-flight or just eating seeds that had fallen on the ground. Instead, I saw something I found to be very intriguing. The juncos were flying up to just below where the seeds were on the grass stem and landing on the stem, which brought the stem back down to the ground. Then these birds would stand on the bent over stem, holding it down with one or both feet, and eat the seeds from the stem tip, which was now laying on the ground at their feet. Once they finished harvesting the seeds on one grass stem, they would release it and repeat the behavior on the next one.

A view of an adult junco holding down the grass stem with its foot on the ground. You can see the bent stem to the left of the bird.

I thought this was so peculiar that I sat there and watched them for a while. Maybe this is not such an unusual behavior for sparrows, but I had never seen something like this before and thought it was quite clever of the birds. I would be curious to know if anyone has observed something similar to this or if any research has been done on behaviors such as these in sparrows or other ground foraging seed-eaters.

Another view of this interesting behavior.

And that is my natural history observation – I hope you enjoy it!

Why hummingbirds are so cool!

For this post, I am going to take a break from posting about my Peru travels to talk about hummingbirds and why they are so cool. My Ph.D. is focused on understanding hummingbird coloration and their courtship displays, but I am always asked why I chose to study hummingbirds over other animals. It certainly was not because they are an easy group to study. Quite the opposite – they can be very difficult to work with in some ways. Throughout this post, I am going to elaborate more on why I chose to study hummingbirds, but also in general, why hummingbirds are so interesting and fun to study. I am also going to include lots of pictures of different hummingbird species, as these are such photogenic animals!

Hummingbirds are only found in the New World (North, Central, and South America). There have been hummingbird-like fossils found in the Old World, and it is suggested that the ancestors of hummingbirds moved from the Old World to the New World through the Bering Straight. The ancestors then theoretically made their way down to South America and hummingbirds evolved from there. Hummingbirds are thought to have evolved about 22 million years ago, based on fossil and genetic data. Some of the oldest hummingbird species are pictures below.

There are roughly 340 species of hummingbirds currently, though new species are still being discovered. While we boast around 20-25 species in the United States, hummingbirds are most diverse in the Andes Mountains and Amazon Rainforest. The country with the most hummingbird species is Colombia, which boasts over 160 species!

Hummingbirds span a wide range of body sizes, with the smallest hummingbird (bee hummingbird) averaging around 2 grams (0.07 oz) and the largest hummingbird (giant hummingbird) averaging around 20 grams (0.7 oz). Many hummingbirds range between 3-7 grams overall (0.11-0.25 oz), and most of the species I study range between 2.5-4 grams (0.09-0.14 oz).

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Museum specimens of a Giant Hummingbird next to a Bee Hummingbird with my hand as a size reference

Hummingbird flight is also very unique relative to birds. They flap their wings in a figure eight pattern, and unlike many birds, they generate similar forces with their upstrokes compared to their downstrokes. Hummingbirds can also hover, a rare trait in birds, and I believe they are the only birds that can fly backwards. Their metabolism is also very fast. Their weight can change quite a bit over the course of a day as they eat and burn up energy. And hummingbirds hearts can beat over 1000 times per minute. This fast metabolism poses a problem at night, when hummingbirds have to go many hours without eating. Some hummingbirds will go into a hibernation-like state at night, called torpor, to conserve energy. They essentially shut off their bodies, and their heart rate can drop from 1000 beats/min to 100 beats/min. This is especially common in hummingbirds that live in colder places or at high elevations. Some hummingbird species like the Ecuadorian Hillstar can occur up to 17,000 feet (~5200 meters) above sea level!

One misconception about hummingbirds is that they only feed on nectar. While they have definitely evolved many specializations for nectar feeding, such as their hovering, long bills, and fast metabolism, they cannot survive on sugar water alone. Hummingbirds feed on insects, such as fruit flies, in order to obtain essential proteins, vitamins, and minerals. However, hummingbird bills can present interesting challenges to eating insects, such as for the sword-billed hummingbird (longest bill to body length of a bird) or the sickle-billed hummingbird (below). Also, hummingbirds interestingly have forked tongues.

Because many hummingbirds live in the tropics, most do not migrate. There are some high elevation hummingbirds that will migrate to lower elevations during the winter/dry season in the tropics. In North America, we have several species that migrate. Some rufous hummingbirds travel from Mexico all the way to Alaska and back every year. Some ruby-throated hummingbirds fly straight across the Gulf of Mexico, an incredible feat for a bird that cannot store too much fat for the long trip. Interestingly, some hummingbird migratory paths have been changing due to hummingbird feeders. Many rufous hummingbirds are now found migrating to the Southeastern US instead of Mexico. Other species have expanded their ranges due to humans. Anna’s hummingbirds have expanded their range into Canada and Arizona, when they originally occurred in California.

There are several reasons I decided to study hummingbirds. The first reason is their crazy colors. You can essentially find every color under the rainbow in hummingbirds, and some species actually do seemingly have every color themselves (like the fiery-throated hummingbird). Hummingbirds also possess a fascinating type of color called iridescence. This type of color looks different depending on the angles it is observed from and the angles it is illuminated from. Essentially, as the hummingbird moves around, the color of its plumage will change, as shown in this video (link). Because I am interested in how behaviors and colors interact and co-evolved, iridescent coloration provides a great system to study these interactions. Overall, the species I study, while very pretty, are actually quite boring relative to many other hummingbird species. Here are a few of my favorite species:

Another reason I study hummingbirds, is that many of them have elaborate dances males perform to females. This is especially true in the 10- species I study. And the interesting part is that the species I study all have similar variations of two types of displays: 1) the dive display ; 2) the shuttle display (link). The dive display is typically where a male flies high into the air, and then dives down over or near his target. The shuttle display is where a male flies rapidly back and forth in front of their target (usually a female), facing it and presenting their throat coloration. Because these displays are similar across species, I can really explore how evolution shaped each species’ specific display and why they are different from each other.

Hummingbirds are also very charismatic and fun animals to work with and observe. They are so bold and curious. They live such fast-paced lives and are always interacting – mostly fighting. And because they occur all over the place, I have gotten to travel all across Arizona, California, and now Peru. Hummingbird’s reliance on nectar can also make it easy to lure them to feeders, where I can observe and catch them. It is still quite difficult to catch a hummingbird sometimes, but feeders definitely help. Overall, hummingbirds are such unique and interesting animals, providing lots of opportunities to study many aspects of their biology. But hummingbirds also provide opportunities to ask broad questions about color and behavior evolution, which is the key reason I am studying them. I actually just submitted my first chapter to a journal, so when that ultimately gets accepted (fingers crossed!) I will blog about those results. For now, I hope this post taught you a few cool facts about hummingbirds and provided a better explanation for why I study them. If you are interested in learning more about hummingbirds, there are two hummingbird-focused PBS Nature documentaries I would recommend. The first is Magic in the Air and the second is one I helped with called Super Hummingbirds (available for free here).

I’m in Peru! An overview of Peru’s diverse habitats

I am currently in the wonderful country Peru as part of a two-trip research venture to study Peruvian hummingbirds. I am expanding my current dissertation from the six species I have focused on in the US to closely related species in Peru. I will talk more about my specific research plans in a later post, but for this first post, I wanted to talk about the incredible diversity of habitats and environments that can be found in Peru.

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A view near the highest elevation I’ve been in my life (4818 m or ~15800 ft) in the Central Andes.

Peru is a fairly large country, roughly twice the size of Texas or just a little smaller than Alaska. Here is an image from the CIA’s website to illustrate the size of Peru compared to the US.

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For biodiversity, in the US and Canada, you can find around 900 species of birds, which is quite a large number. However in Peru, there are over 1800 species of birds, which is one of the highest numbers in the world. And that is just birds. There are over 500 species of mammals, 600 species of reptiles and amphibians, tens of thousands of insect species (including over 4000 butterfly species), and over 20000 species of plants. Those are incredible numbers, but how does Peru obtain such biodiversity? Through a combination of the Amazon Rainforest, Andes Mountains, and the Pacific Ocean.

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A view of Lake Junín and its surrounding wetlands in the Central Andes (~4000 m or 13,000 ft).

Peru can broadly be broken down into three distinct regions: 1) the desert coast; 2) the sierra (Andes Mountains); 3) the Amazon. These regions vary from west to east, with the coast on the west and Amazon on the east. Peru can further be broken down from north to south. Northern Peru has some of the lowest mountains in the Andean chain and is close to the Equator, which leads to very different seasonality and the presence of tropical dry forests near the coast instead of just barren desert. Central and Southern Peru are somewhat similar, but the Andes are wider and higher (on average) in Southern Peru.

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Looking down into the Santa Eulalia Valley on the west slopes of the Andes Mountains.

The Andes Mountains dictate much of the biodiversity in Peru, though the Amazon contributes a ton as well. Peru’s mountains have a very dry west slope, which is fairly close to the Pacific coast, and a very humid and wet east slope. In the middle, there are several large plateaus and valleys, that have their own unique properties, such as the Marañon, or temperate deciduous forests, in Northern Peru’s Andean valleys, and the high elevation, cold and dry Puna grasslands found in throughout the high Andes (over 3500 m or 11500 ft). As you move up in elevation on both slopes, but especially the east slope, the plant and animal compositions change drastically. This can be best witnessed on the east slope, as you start in specialized high elevation humid forests, such as Elfin forests, and then descend into typical cloud forests, which harbor amazing biodiversity, before dropping into the varied and vast lowland Amazon rainforest.

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The cloud forests on the east slopes of the Andes, in Central Peru

So far, I have mostly stuck to the coast and west slopes of Peru. I have spent most of my time in Lima, which is the capital of Peru, and in the Peruvian coastal desert. Peru’s coastal desert is one of the driest places in the world, but also is home to the spectacular mist oases, called Lomas.

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A view of the mysterious and spectacular mist oases in the super dry Peruvian desert. This is at Lomas de Lachay.

I made two trips into the Andes from Lima, one sticking on the west slopes, and one going into the heart of the Central Andes, where I hit 4818 m (~15800 ft) and explored the Puna grasslands and a high elevation lake named Lago Junín. While I was in the Central Andes, I did take a day-trip to the east slope cloud forests, which allowed me to see a completely different side of Peru. I also took a five-day trip to Northern Peru, still sticking to the coast, but where I explored Peru’s tropical dry forests. Overall, I have only explored a small bit of Peru, but it has been am amazing visit full of many unique experiences for me! Over the next several posts, I will document these experiences, and then next Spring (for us) I will return to Peru to continue my work on hummingbirds!

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A pristine tropical dry forest of Northern Peru (photo a bit washed out). This is at the Santuario Historico Bosque de Pomac.

You’re not a hummingbird!?

One of the best ways to see hummingbirds is by putting up a hummingbird feeder. Feeders come in all shapes and sizes and can go from very cheap to un-necessarily expensive. Regardless of the feeder, so long as it attracts hummingbirds you can enjoy these amazing birds. I’ve been fortunate enough to set up feeders in a variety of locations, which has enabled me to see many different species of hummingbirds. Here are a few pictures of different species I’ve seen at feeders in Panama, California, and Arizona:

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White-necked Jacobin in Panama

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More white-necked Jacobin and a violet-crowned woodnymph in Panama

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An Allen’s hummingbird in California

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A male broad-billed and female black-chinned hummingbird in Arizona

While you might think hummingbird feeders only attract hummingbirds (hence the name), you will find out otherwise. Some of the common alternative attractants to hummingbird feeders are bees, wasps, and ants. My experience with wasps is mainly from Panama, where there would be one or two hanging around the feeder, but not enough to prevent hummingbirds from also drinking. I have also not had too much trouble with bees, however when they find your feeder they can cover it. I have come up to my feeders before to find 30-50 bees on it. In my experience, the best way to avoid bees is to make sure your feeder does not leak or drip sugar water. If bees do find your feeder, take it down for a few days and then move it to a different location and hopefully the bees will not find it again. Ants are a bit harder to avoid. They tend to be experts at finding feeders. Many end up dead inside the feeder, which can lead to some lovely mold growths if not cleaned quickly. But many ants will just hang out in a feeder and you will not necessarily notice them until you move the feeder and they come swarming out. The best way to avoid ants, is to use ant guards. The feeders I use for fieldwork (below) have built in ant guards, which kind of work. To better ensure the success of the ant guard, fill the top part with some water (which unfortunately will not last long in Arizona).

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In addition to ants/bees/wasps, you can attract several other bird species to hummingbird feeders. I’ve seen woodpeckers, orioles, house finches, and tanagers all try to partake in the delicious sugar water from a feeder. While these birds can scare off hummingbirds, they will not stay at the feeder all day, so hummingbirds will still visit the feeders. The main issue with these birds, is that they tend to spill a lot of the nectar from feeders because they tip it over. Sometimes woodpeckers will also break feeders, trying to drill into them! I’ve been lucky in that most of these other bird visitors were just fun birds to watch and did not have any major negative effects on the feeders. Here are a few pictures I have of non-hummingbirds at my feeders:

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A Scott’s Oriole waiting to jump on the feeder.

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Two house finches sharing my feeder.

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This acorn woodpecker was patiently waiting for me to fill up the feeder so he could have a drink

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A known hummingbird feeder breaker: The Gila woodpecker!

Now you might ask what this post has to do with my fieldwork. Well I deal with hummingbird feeders at lot in my work, as that is the best way to catch wild hummingbirds. Here are two of my setups to trap hummingbirds using feeders:

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My feeder drop trap. Easy to setup, but sometimes hummingbirds can be too fast and escape, or they are too afraid to enter the trap.

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An open box made from pvc pipe and mist-nets with a feeder and caged female as a lure. Much more likely to work, but is a huge pain to set up.

 

The past several days, I have been working to capture the three males I filmed last week with Jess and Aly. This week, I finally managed to capture them all! It took longer than normal to capture these three males, partly due to some crazy winds, but in the end I succeeded. While I was using the mist-net method of trapping these hummingbirds (see picture above), I ran into other species going in my traps – mainly Scott’s orioles. Here is  one in my trap:

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Also, I often had to deal with hummingbirds that were not the target male I was trying to capture not being able to get out of my trap, like this female broad-billed hummingbird who just clung to the side of the nets.

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Anyways, now that I’ve caught all of my male hummingbirds, its time to finish analyzing all of the display videos and start taking pictures of each male’s feathers. I’ll provide the details and a better explanation in my next post. In the mean time, I would highly encourage all of you to put up hummingbird feeders in your yards so that you can also enjoy these wonderful birds! Just remember to clean your feeder to avoid mold and do not use red dye in the sugar water! It is bad for the hummingbirds. All you need is sugar (raw sugar is best) and water (I typically use 1 part sugar to 4 parts water) and you are good to go. Happy hummingbird (and non-hummingbird) watching!

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A male black-chinned hummingbird waiting for this house finch to leave.