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Bringing Research to Light

February 18, 2011

The Research Staff of the North Carolina Museum of Natural Sciences includes experts in a wide variety of scientific disciplines who conduct exciting research investigations, maintain and expand the Museum’s natural science Research Collections, and participate in the Museum’s public education and outreach mission.  Check this blog often to learn about all of the great science happening at the Museum!

Happy Birthday, Carl Sagan!

November 9, 2014

One of the great astrophysical minds and proponents for reaching beyond our limits as a species, was Dr. Carl Sagan, born today, November 9, 1934. Dr. Sagan died from an illness in 1996, but his voice and contributions to exploring the cosmos live on.

Carl Sagan was a big supporter of SETI — the Search for Extraterrestrial Intelligence — and he convinced NASA to put the Golden Records on the Voyager Probes, now just beyond the solar system, in the slim, slim chance an intelligent alien civilization might eventually find them. He believed in reaching past our limitations as a species, while protecting our small planet and its inhabitants. Dr. Sagan’s original 1980 television series, Cosmos: A Personal Voyage, put astrophysics and exploration of the Universe on the map of public interest — an achievement that survives today. He hoped to one day see a human colony on Mars, and perhaps, if still alive, he might have helped push our space program to achieve that goal.

Perhaps one of Dr. Sagan’s most profound speeches, The Pale Blue Dot, centered on the image of Earth taken, on his suggestion to NASA, with one of the Voyager probes at a distance near the outer planets. This image showed Earth, for the first time, as a tiny dot in a vast sea of space, and generated a more humble perspective of our place in the cosmos. His voice, along with the Voyager images he inspired, can still be enjoyed, below:

You can read more about the Voyager mission and its journey out to interstellar space here.

Revolutionary Image of Planet Formation Around a Young Sun-like Star

November 8, 2014

A few days ago, astronomers using the Atacama Large Millimeter Array telescope (or, ALMA) released this astonishing image:

Protoplanetary disk surrounding the young star HL Tau (Credit: ALMA (NRAO/ESO/NAOJ); C. Brogan, B. Saxton (NRAO/AUI/NSF).

Protoplanetary disk surrounding the young star HL Tau (Credit: ALMA (NRAO/ESO/NAOJ); C. Brogan, B. Saxton (NRAO/AUI/NSF).

This is an image of a protoplanetary disk — the ring of gas and dust that astronomers think surrounds most forming stars (or, protostars). The image amazes for a few reasons. It is the first image to show the detailed concentric rings indicative of planet formation in a protoplanetary disk. This visualization of real-time planet formation looks startlingly like artistic renderings of protoplanetary disks often used in interpreting fuzzy astronomical images.

Artistic rendering of a protoplanetary disk around a young star, much like HL Tau. Planets are shown forming in the gaps in the disk (Credit: National Science Foundation, A. Khan).

Artistic rendering of a protoplanetary disk around a young star, much like HL Tau. Planets are shown forming in the gaps in the disk (Credit: National Science Foundation, A. Khan).

Even more interesting, perhaps, is that the protostar, HL Taurus (often referred to as HL Tau), is less than one million years old, too young, scientists thought, to have a forming system of planets. The now certain fact that there are orbiting bodies well on their way to planet hood implies that planets can form far earlier than originally thought. An earlier history for planet formation means that initial thinking on the chemistry and physics that drive planet formation will need to be reconsidered.

HL Tau is a Sun-like protostar that resides about 450 light-years from Earth in the constellation Taurus (the Bull), but being in the pre-star phase of its evolution and surrounded by a large disk of gas and dust renders it only visible at infrared wavelengths. Being similar in mass and type to our Sun, it is one of the best analogues for the early Solar System, and astronomers study the chemistry of the gas and dust surrounding this and other protostars like it to better understand how our own planetary system evolved.

This image is particularly fascinating for me, since my colleagues and I recently submitted for publication to The Astrophysical Journal (Smith et al., now in revision) one of the most detailed chemical analyses of HL Tau taken with the powerful Very Large Telescope (VLT) in Chile. Our analyses of our very high-resolution observations of carbon monoxide absorption lines in the gas surrounding this object revealed patterns in the oxygen isotopes that are consistent with the as-yet-unexplained patterns seen in the most primitive meteorites, hinting at early solar system processes that could have contributed to this unusual chemistry.

Spectrum of carbon monoxide gas in the protoplanetary disk surrounding the young protostar HL Tau, taken with the Very Large Telescope (Credit: R. Smith, Smith et al., The Astrophysical Journal, paper in revision).

Spectrum of carbon monoxide gas in the protoplanetary disk surrounding the young protostar HL Tau, taken with the Very Large Telescope (Credit: R. Smith, Smith et al., The Astrophysical Journal, paper in revision).

Now it seems that what we once considered primitive, pre-planetary processes could in fact be affecting planets directly as they form. These new revelations will likely change how we interpret our astronomical observations, and how we understand the early chemistry affecting planet formation, organic compounds, and, eventually, life.

You can watch a brief webcast from the National Radio Astronomical Observatory discussing this new image of the HL Tau exoplanetary system below:

 

Click the highlighted links to learn more about my research on solar system origins, and the Astronomy & Astrophysics Research Lab at the Museum!

Making History: Rosetta Catches its Comet on November 12!

November 8, 2014

It’s an exciting time for solar system scientists, as on Wednesday, November 12, 2014, the European Space Agency‘s Rosetta mission will become the first spacecraft in human history to land on a comet — one of the primitive, icy bodies that are left overs from our solar system’s formation about 4.6 billion years ago.

Rosetta is scheduled to touchdown on comet 67P/Churyumov-Gerasimenko (“67P/C-G” for short) at 10:35 AM Eastern Time, with a signal confirming the landing reaching Earth at 11:03 AM. A live-stream of the landing will be available as a webcast, and a special free public program will be held in our Daily Planet Theater, including the live stream and presentation by Dr. Rachel Smith, Director of the Astronomy & Astrophysics Research Lab at the Museum.

Artistic rendering of Rosetta's robotic lander, Philae, touching down on Comet 67P's surface (Credit: NASA).

Artistic rendering of Rosetta’s robotic lander, Philae, touching down on Comet 67P’s surface (Credit: NASA).

Rosetta first made history on August 4, 2014, when it awoke from its ten-year hibernation while en route to comet 67P/C-G to became the first spacecraft to lock in synchronous orbit with a comet. When its robot lander, called Philae, will deploy next week, Rosetta will begin unprecedented detailed studies of the comet’s nucleus — the big chunk of ice and rock that comprises much of the mass, and coma — the material that spews off the surface when it begins to sublime during its approach toward a few hundred million miles of the Sun. This spewed material creates the images that we are perhaps most familiar with when we think of comets coming close to Earth.

Partos

Anatomy of a comet, showing the nucleus, coma, and tail (Credit: NASA).

Comets are thought to be one of the most primitive groups of solar system bodies, vestiges of our early formation that hold clues to our chemical origins. Like the asteroids we see more frequently (and pieces of which we find on Earth as meteorites), comets impacted Earth and other planets and moons in the past. One of the most burning questions that Rosetta will help answer is how Earth obtained its oceans; many scientists think that comets could have seeded our planet’s oceans through impacts during our early history several billion years ago. In 2011, spectroscopic measurements from the Herschel Space Observatory showed that water from comet Hartley 2 was chemically very similar to Earth’s water; Rosetta will analyze the chemistry of water in Comet 67P/C-G in even greater detail to thoroughly investigate the comet origin theory.

Could comets have seeded our oceans billions of years ago? New analyses and missions to comets are helping scientists investigate this question (Credit: NASA/JPL).

Could comets have seeded our oceans billions of years ago? New analyses and missions to comets are helping scientists investigate this question (Credit: NASA/JPL).

Further, in 2006, the mission Stardust passed through the tail of comet Wild 2, collecting tiny particles that were found to be rich in organic matter. These particles support the theory that, like our oceans, organic molecules, including the building blocks of living organisms, could have been seeded by cometary impacts. One of  Rosetta’s key scientific missions will be to study a detailed inventory of Comet 67P/C-G’s chemical, mineralogical, and isotopic composition in order to advance our understanding of organics on comets and how they may relate to the origin of life on Earth.

Comet 67P/C-G is about 3 AU from the Sun, or 450 million km, about 3 times the distance from the Earth to the Sun. After landing its robot onto the surface, Rosetta will travel with 67P/C-G as it travels to the inner solar system and is heated by the Sun, enabling first-ever studies of detailed changes to a comet occurring during its approach to perihelion (a body’s closest distance to the Sun).

Earlier this year, Rosetta’s cameras sent images of the 67P/C-G’s surface, showing its dual-lobed surface in startling, first-ever detail. A few of these spectacular images are shown below; you can find a wider selection of images from Rosetta on the JPL website.

Comet 67P/Churyumov-Gerasimenko's dimensions, as measured from images taken by Rosetta's OSIRIS imaging system. The images shown in the graphic were taken by Rosetta's navigation camera on August 19, 2014. The larger lobe of the comet measures 4.1 x 3.2 x 1.3 km, while the smaller lobe is 2.5 x 2.5 x 2.0 km (Credit: ESA/Rosetta/NAVCAM; Dimensions: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA).

Comet 67P/Churyumov-Gerasimenko’s dimensions, as measured from images taken by Rosetta’s OSIRIS imaging system. The images shown in the graphic were taken by Rosetta’s navigation camera on August 19, 2014. The larger lobe of the comet measures 4.1 x 3.2 x 1.3 km, while the smaller lobe is 2.5 x 2.5 x 2.0 km (Credit: ESA/Rosetta/NAVCAM; Dimensions: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA).

Comet 67P on November 4, 2014. This mosaic comprises four individual  images taken with Rosetta's "NAVCAM" camera from 31.8 km from the center of the comet. The original 1024 x 1024 pixel frame measured 2.8 km across. The mosaic has been slightly rotated and cropped, and measures roughly 4.6 x 3.8 km (Credit: ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0).

Comet 67P on November 4, 2014. This mosaic comprises four individual images taken with Rosetta’s navigation camera (NAVCAM) from 31.8 km from the center of the comet. The original 1024 x 1024 pixel frame measured 2.8 km across. The mosaic has been slightly rotated and cropped, and measures roughly 4.6 x 3.8 km (Credit: ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0).

Four-image montage comprising images taken by Rosetta's navigation camera (NAVCAM) from a distance of 9.7 km from the center of comet 67P, about 7.7 km from the surface. The corresponding image scale is about 65 cm/pixel, so each 1024 x 1024 pixel frame is about 665 meters across. (Credit: ESA/Rosetta/NAVCAM)

Four-image montage comprising images taken by Rosetta’s navigation camera (NAVCAM) from a distance of 9.7 km from the center of comet 67P, about 7.7 km from the surface. The corresponding image scale is about 65 cm/pixel, so each 1024 x 1024 pixel frame is about 665 meters across. (Credit: ESA/Rosetta/NAVCAM)

Next week’s soft landing will be scientifically groundbreaking, and one of the most exciting times for planetary science! Join us on Wednesday in the Daily Planet theater to witness this live landing, and hear more about Rosetta’s science and technological breakthroughs.

Solar system research at the Museum: I am an observational astronomer studying solar system origins from a different vantage point: outside of our solar system. I use the largest ground-based optical/infrared telescopes to study the chemistry of forming planetary systems in our Galaxy, and compare these data to the oldest material from our solar system, including meteorites, the Sun, and hopefully soon, Comet 67P/C-G. Visit my Museum webpage and other research blogs as well as the astrophysics displays in the Astronomy & Astrophysics Research Lab and the Museum’s meteorite collection to learn more!

Camera traps offer a peek into the minds of nervous deer

August 20, 2014
by

Last summer I was going fishing as part of an inland fisheries class with North Carolina State University’s (NCSU) Wildlife Summer Camp. While I was walking around the pond to secure a section of the bank to fish, I stumbled upon a baby white-tailed deer, which was curled into a ball near the pond bank. It didn’t move or make a sound. In fact, I reached down and scooped it into my arms before my teacher, a deer researcher at NCSU, and classmates caught up to me. Because we were part of a class, we had appropriate permits to handle wildlife (don’t try this at home). We learned how to age the fawn based on size and behavior and determined it was only seven days old! The fawn was not stressed, so we took pictures, before releasing it back where it was hiding. We loved the experience of seeing a wild deer fawn up close, but why hadn’t the little guy run away as we approached?

Student holding a seven-day old wild deer fawn found during summer classes.

A fawn, about seven days old, captured by NCSU students during summer classes in 2013.

Deer fawns are covered in hundreds of white spots (300 on average) that help to camouflage them. For the first one to two weeks of life, white-tailed deer rely on this camouflaging pattern to protect them from predators. Rather than fleeing at a sign of danger, fawns stay motionless to avoid detection. Mothers commonly leave their fawns for hours at a time, before returning to let the fawn nurse. The following photos show how well fawns are camouflaged (note that the young were radio-collared as part of a research project).

Fawns are camouflaged by their white spots, even in seemingly open areas.

A fawn lying on the ground beside a pinecone with a collar that allowed NCSU researchers to monitor its survival. Do you see it?

Fawns are nearly invisible when surrounded by dense vegetation because of their white spots.

A fawn lying on the ground among dense vegetation. Can you find it?

During the second week of life, young deer are steadier on their feet and will flee rather than sit still when threatened. By the fourth month of life, the protective white spots that once covered their fur start to disappear. Predators remain a threat to deer and after losing their camouflaging spots, these young deer must find new ways to avoid predation. Mainly, they adjust by being on the lookout for predators, and then running away as fast as they can if they sense danger. When deer are looking for predators, they are exhibiting what we call vigilance behavior: they hold their heads high, often with perked ears, looking and listening for potential threats. However, vigilance comes at a cost; there is a trade-off between having your head up to keep an eye out for predators and having it down near the ground to browse for food. Thus, vigilance behavior can directly influence the health of each individual deer because it takes away from the amount of time they can spend foraging. Of course, vigilance is worth it because it helps keep them alive if deer-eating predators are stalking nearby.

A doe exhibits vigilant behavior with a lifted head and perked ears.

A camera trap records a doe exhibiting vigilance behavior (above) and then looking for a bite to eat a few seconds later (below).

The same doe as above forages for something to eat with her head down, trading her ability to search for predators.

Scientists are increasingly interested in measures of deer vigilance because it provides a window into how deer see the world – a direct way to measure how nervous a deer is. With a metric like this, we can start to ask questions about what types of things make a deer more or less nervous, and therefore, more or less able to browse the local vegetation. Camera traps and direct observations are ways researchers can watch this behavior and several new studies report factors that influence deer vigilance.

In one study on deer vigilance in North Carolina, researchers baited 100 motion sensitive camera traps and used the pictures to determine how often the animals had their heads up looking for predators, or down munching the corn bait. After coding the behavior of 40,000 deer photos they discovered that deer increased their feeding time (i.e. were less nervous) as their social group size increased. Their results make sense; more eyes in the group allowed individuals more time for feeding, rather than looking for predators. They also determined that males were less vigilant than females, meaning they spent more time foraging. The researchers hypothesized this behavior was due to males’ larger body size, which might make them less likely to be attacked by a predator (primarily coyotes at this site).

Another project with elk in Montana found that all-male herds were less vigilant than herds with females, and that a higher calf-to-cow ratio resulted in a more vigilant herd. The North Carolina deer study also found this result: when fawns were present, females were more vigilant than when no fawns were present.

Does are more vigilant when they have fawns.

A doe with a young fawn exhibits vigilance behavior.

The North Carolina study also evaluated vigilance compared to time of day and moon phase. Deer were less vigilant in the afternoon and during brighter moon phases, likely because they were better able to see approaching predators.

Meanwhile, another group of researchers in Poland determined that olfactory cues, like fresh wolf scat, also affect vigilance in red deer. Red deer doubled their vigilance behavior when wolf scat was present, suggesting that predators’ scent alone can put deer on high alert. When deer smell that predators may be nearby, they are much less likely to forage, but rather spend their time looking for those predators.

Together, these studies show that camera traps can be great tools for studying the factors that affect deer predation risk. They have confirmed the importance of group size in protecting against predators, and suggest that prey also adjust their defenses daily based on light levels, and locally if they smell a predator. However, I think we are just starting to scratch the surface at what else we can learn about predator-prey systems with this new vigilance measure, and I’m happy to be helping with a new study that extends this past work by analyzing deer across 32 parks in the eastern United States.

eMammal is a citizen science research project that enlists local volunteers to run camera traps and then share the pictures with scientists. At the Biodiversity Lab of the North Carolina Museum of Natural Sciences, we are now going through these pictures and quantifying how nervous each deer is, how often they have their head down to feed, or up to look around. This data set is stratified across areas of different human use, so we will be able to evaluate the effect of people, as well as coyotes, on deer behavior. Some of our cameras are in hunted parks, while others are in unhunted lands. Some are on busy hiking trails, remote hiking trails, or off in the middle of the woods, allowing us to also check to see if human foot-traffic is important to deer. Finally, we also get counts of coyotes on these cameras, so we will factor them into the analysis as well.

I often come across fawns in the pictures we are using for this study and laugh as they play or chase insects in front of the cameras, always thinking back to the fawn I found last summer.  Although we don’t have any conclusions yet from these images, we will soon be able to add up all of our data and plot results – I can’t wait for that eureka moment.  Whatever we discover, I will present a poster on this research at The Wildlife Society meeting in October.

Follow me on Twitter @sumdawg to see the best pictures from the research!

Don’t forget to follow @eMammal on Twitter and like EMammal on Facebook for exciting updates from our research!

Greetings from Comet 67P/Churyumov-Gerasimenko! Wish you were here…

August 6, 2014

It may be a mouthful to say, but Comet 67P/Churyumov-Gerasimenko — partly named after its co-discoverers —  made history today as the first comet to encounter  and undergo synchronous orbit with a human-made spacecraft, which will eventually land on its surface, and follow it over the next several years as it nears the Sun. Known as Rosetta, this international mission is a cornerstone of the European Space Agency’s Science Program. Today, it made its first rendezvous and orbit with its icy comet target.

Artistic rendering of Rosetta orbiting Comet 67P/Churyumov-Gerasimenko (Credit: ESA, image by AOES Medialab).

Artistic rendering of Rosetta orbiting Comet 67P/Churyumov-Gerasimenko (Credit: ESA, image by AOES Medialab).

Rosetta and comet “Chury” (for short) are locked in orbit at about 405 million km from Earth. When Rosetta lands on Chury, it will conduct scientific measurements of chemistry and physical properties on a comet nucleus, feats never before possible with the fly-by missions of the past. Solar system scientists hope that the information gained by Rosetta will unlock clues to the origin of the solar system, some of which lie hidden inside some of the most primitive, and hard to reach bodies of the solar system — the comets.

The comet will eventually pass far beyond the orbit of Jupiter, accompanied by Rosetta.

Today’s feat was accompanied by new images (“Postcards”) of the comet’s surface, such as the one below.

Close-up of comet 67P, taken by Rosetta (Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA)

Close-up of comet 67P, taken by Rosetta (Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA)

You can enjoy many more of these unprecedented images here.

 

The Story of Mr. Bisbing, Part V: Tag Recovery from Colombia

July 25, 2014

This is the last chapter of our story about a great egret that we gave a GPS tracking device on the Outer Banks of North Carolina in spring 2013 (see photo). We followed his movements for about 8 months and reconstructed his story with his GPS and ACC data (see parts I, II, III and IV).

Mr. Bisbing, a great white egret with our tag on his back.

Mr. Bisbing, a great white egret with our tag on his back.

This was the first time that an egret’s migration has been recorded in such detail and, as you could see through this blog, we learned some quite amazing things about this bird.

Mr. Bisbing had spent his summer within the Outer Banks, breeding and raising chicks with a mate, then taking it easy in the wetlands south of Roanoke Island. As the days became shorter toward the end of September, he started becoming unsettled, and on October 24th he took off, flying south over the open ocean. He migrated all the way down to Colombia, stopping for a few days in the Bahamas, Cuba, and Jamaica.

Finally, when Mr. Bisbing arrived in Cesar Province, Colombia, our data show that he started foraging in the same routine manner detected while he was in North Carolina (Fig. 1).

 

PartV_Fig2

Figure 1. Mr. Bisbings last movements (pink lines) in Colombia.

Suddenly, on Dec. 8th his movements stopped. His tag was still sending data, so it must have been in a sunny location to keep powering the solar panel of our tag. It took us a few days to realize that the tag had completely stopped moving, and that Mr. Bisbing had probably died, or possibly dropped the harness off his back.

Our next challenge was to go to the site to see if there was a dead bird, and recover the tag, so that we could download the detailed data (the daily text messages from the tag to us just sent us a subset of the data) and analyze the results. We started asking around among colleagues and birders to find someone locally in Colombia who would be able to search for the tag at this the GPS location.

On March 3rd, Mr. Curtis Smalling (Director of Land Bird Conservation, Audubon North Carolina) sent a note to the group, ProAves, a Colombian bird group, asking if anyone would search for the radio-tagged egret for us. On March 20th, Dr. Matthew Godfrey (sea turtle program leader, NCWRC) informed us that he gave all the information we had provided to him to his Colombian colleague, who in turn, posted the request on the Colombian Bird Network.

On March 19th, we received an email from Magaly, who told us that she would search for the tagged bird! We found a biologist, who was willing to help us, far away in Colombia!!! She asked a few questions about the frequency of the tag and the exact GPS location, then started her search.

She found the tag exactly where we thought it was, and also the feathery remains of Mr. Bisbing in Plot No. 16 of the San Miguel, Vereda, The Navajo town of El Copey Cesar, Colombia. We are very grateful that Magaly volunteered to take her time to recover and send the tag back to the Museum of Natural Sciences in Raleigh.

But what caused Mr. Bisbing’s death? The area that he chose to forage in had been affected by an unusual summer with no rain in five months and the vegetation was very dry as evident in pictures from the area (Fig. 2).

 

PartV_Fig3

Figure 2. The area in which Mr. Bisbing died: Plot No. 16 of San Miguel, Vereda the Navajo, Town of El Copey Cesar, Colombia.

The only water sources were man made wells for cattle. One of the farm workers (Fig. 3) reported to Magaly that he had seen the dead heron and its transmitter about two months before she arrived looking for it. He did not handle the dead bird but observed, that he “did not see any wounds on the bird”.

PartV_Fig4

Figure 3. Biologist Magaly Elizabeth Ardila-Reyes who recovered the tag and a farm worker who found Mr. Bisbing dead and unharmed on the ground.

We assume that Mr. Bisbing died of starvation and exhaustion after the long migration. He chose a foraging area that didn’t provide enough food to recover from his depletion of reserves. Was he inexperienced in this area, or was it the unusual summer that turned his trip into a disaster? We will never know about this individual bird, but if we keep observing more egrets and follow their way through life, we will hopefully understand more about how and why they choose locations to spend the summer or winter, and what their preferred migration pathways are.

We have tagged other great egrets and found that they each have an individual schedule and have quite different preferences regarding foraging areas or migration routes. You can see their movements on movebank.org and find out in which areas Ms. Palma, Mrs. Newbern, Mrs. Kelly, Mrs. Heller, Mr. Norvell, and Mr. Meadows preferred to live and migrate.

With the detailed observation of Mr. Bisbing, for example, we found that at least this bird preferred migrating during the night. There are only a few observations of migrating great egrets reported prior to our study, and they stated that great egrets migrate during the night. We were pleased to find that these older reports were confirmed by our study.

This new, detailed knowledge about breeding behavior, foraging preferences, migration pathways and timing, etc. will help us protect great egrets and increase their survival in our more and more urbanized environment.

You can participate and help us in these efforts, too, by using a new application called Movebank. With this app you can follow birds live in real-time, and go out in the field to find the tagged birds, take pictures and send them back via the application. So give it a try, check out the location of the closest bird, get into your car and enjoy the search.

 

The Story of Mr. Bisbing, Part IV: Migrating South

July 23, 2014

This is the fourth chapter in the story about a great egret that we gave a GPS tracking device on the Outer Banks of North Carolina in spring 2013 (see photo). We followed his movements for about 8 months and reconstructed his story with his GPS and ACC data (see parts I, II and III).

BisbingBuckler

Mr. Bisbing, a great white egret with our tag on his back.

On October 24th at 9 p.m., Mr. Bisbing took off for his last long trip. Up to that point he had spent his summer within the Outer Banks, breeding and raising chicks with a mate, then taking it easy in the wetlands south of Roanoke Island. Everything seemed to be orderly and his daily routine was relaxed and regular. As temperatures got colder toward the end of September, he started becoming a bit unsettled. He checked out new foraging areas, drifted farther and farther south, but still returned to his roost every night. Eventually, he overcame his inhibitions and took off flying south away from the Outer Banks, over the open ocean.

During his migration, Mr. Bisbing covered a total of about 3200 km (2000 miles) (Fig. 1). He started with an impressive 22.5-hour nonstop flight (from Oct. 24th, 9 p.m. until Oct. 25th, 7:30 p.m.) from his roost south of Roanoke Island straight across the ocean to the Bahamas, where he took his first break. During this first nonstop stage he covered more that 1200 km (about 755 miles)!

Figure 1. Mr. Bisbing’s migration from the Outer Banks of North Carolina to Colombia. Yellow circles mark his resting areas.

But why do egrets migrate at all? Bird migration is the regular seasonal movement, often like in our case, north and south along a flyway between breeding and wintering grounds. Migration carries high costs in predation and mortality but many species of birds have to risk it because of the availability of food. Great egrets like Mr. Bisbing feed on fish and other small vertebrates such as amphibians, reptiles and mice. During winter all these vertebrates appear less abundant, because many of them hibernate. So egrets need to find foraging areas with higher abundances of their preferred food.

Timing of migration is controlled primarily by changes in day length. For navigation birds often use celestial cues from the sun and stars, the earth’s magnetic field, and probably also mental maps. Mr. Bisbing flew across the ocean, during the night, so we can assume, that he had no visual orientation to navigate. Nevertheless he found his way back to a shore and foraging grounds to regain some strength. We were quite surprised to observe that when migrating, Mr. Bisbing was flying actively, flapping his wings nonstop, without soaring as birds of similar size and body shape like storks or cranes do (Fig 2).

PartIV_Fig2

Figure 2. Mr. Bisbing’s first stage of migration south. Close-up shows wing beats, grey bars show nighttime.

After his first landing in the Bahamas, he rested for only 80 min before he flew farther south for another 35 min. Here, in the south of Greencastle, he found a wetland and rested for the rest of the night. He slept-in the next morning and took off at 9:40 a.m. to forage in the surroundings. But he took only one day to recover from the long and exhausting flight, spending his time resting and foraging (Fig. 3).

Figure 3. Mr. Bisbing's foraging tracks (pink lines) in the Bahamas on October 26th.

Figure 3. Mr. Bisbing’s foraging tracks (pink lines) in the Bahamas on October 26th.

Why Mr. Bisbing didn’t stay in Bahamas longer we will never know, but in the evening of October 26th at 8:00 p.m., he flew another 435 km (270 miles) south over the Caribbean. It took him 6 hours, and by 2 a.m. he reached the northeast coast of Cuba. He rested there for a few days in a quite regular daily pattern, as he used to do before the migration: waking up at 7 a.m. and spending the day foraging until 8 p.m., when he went to bed at his roost (Figs. 4 and 5).

Figure 4. Mr. Bisbing's normal daily routine with foraging and resting, in this case during a migration stop-over in Cuba.

Figure 4. Mr. Bisbing’s normal daily routine with foraging and resting, in this case during a migration stop-over in Cuba.

Our ACC data record ends on Nov. 2nd at 1 a.m.. We were not able to download any data from the memory card during Mr. Bisbing’s migration, so the ACC memory card filled up and stopped recording. From now on, we don’t have any more details about his body movements, but we could still follow his regional movements, because the GPS was still working. The resolution was lower, due to the memory limitation, but we received a few points every day to follow his large scale movements.

PartIV_Fig5

Figure 5. Mr. Bisbing’s foraging tracks (pink lines) in Cuba.

After 20 days in Cuba, Mr. Bisbing was on the move again, migrating 400 km (about 250 miles) farther south to Jamaica on November 15th. He found a roost south of Pamphret (Fig. 6) and stayed in this area for almost two weeks, until November 27th.

Figure 6. Mr. Bisbing’s foraging tracks (pink lines) in Jamaica.

Figure 6. Mr. Bisbing’s foraging tracks (pink lines) in Jamaica.

The next data we received are from November 29th, and at this time, Mr. Bisbing is already in 960 km (about 600 miles) farther south in Colombia, south of Momil in Cordoba Province, where he stayed for another day. From there he flew another 212 km (133 miles) farther northeast, to Cesar Province.  The GPS tells us that he arrived here on December 2nd and he stayed and foraged in this area for another couple of days – until his movements stopped on December 8th. This was the last step of his migration, indeed, the last flight of Mr. Bisbing. What happened next to our tragic hero, and how we got the tracking tag back from South America to North Carolina will be the subject of our final blog post about Mr. Bisbing the great egret.

 

 

 

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