Author Archive

The Banner-tailed Kangaroo Rat: The Once – but probably not future – King

July 27, 2016

In 1977 when Jim Brown, Diane Davidson, and Jim Reichman started the Portal Project, the site looked like this:


Photo of Portal Project from around 1977 (we think).


This desert heaven was home to a variety of small mammals. One of the most abundant of these was the Banner-tailed Kangaroo Rat. While I feel that most small mammals are adorable (*cough* *cough* Packrat), the Banner-tail is the one that is universally beloved by generations of Portal researchers.


summer 110

Banner-tailed Kangaroo Rat (Dipodomys spectabilis). How can we tell? Note its size relative to the hand and the white tuft at the end of the tail.

Kangaroo rats in general are lovely creatures. As their name suggests, these nocturnal rodents hop around like kangaroos on enlarged backlegs. As least one scientist has seen a kangaroo rat use those strong back legs to leap 5 feet horizontally (with a two foot ground clearance)1. They have a long tail which may play a role in locomotion1 and fur-lined cheek pouches that they use like a bag to carry around seeds they gather from the environment. Most kangaroo rats eat primarily seeds. A study in Nevada found that Merriam’s Kangaroo Rat (a species we have at Portal) has a diet of  approximately 70-100% seeds (it varies over the year) and they eat a small number of insects as well.2 Anyway, you get the idea, kangaroo rats in general are cool. Most kangaroo rats – like Merriam’s – are about 40-70 grams (that’s about 0.09-0.15 pounds). But there are a few kangaroo rats that are notably larger. The Banner-tailed Kangaroo Rat is one of these, being closer to ¼ of a pound.


So, in 1977 three kangaroo rats, alike in dignity in fair Portal where we lay our scene, coexisted without evidence of ancient grudge or new mutiny4: Banner-tails (Dipodomys spectabilis), Merriam’s (Dipodomys merriami) and Ord’s (Dipodomys ordii).

The plot below shows the population dynamics of the three kangaroo rats. The plot goes from 1977 to 20145 and shows the population size in energy use6. I like energy use – especially when I’m dealing with Banner-tails – because large animals need more food than small animals. So one large banner-tail needs the equivalent amount of energy as 2¾ Merriam’s (based on their metabolic rates). By converting the population numbers to energy use, it helps correct for this difference in food consumption. So, the graph shows that early on in the study, Banner-tails were energetically more dominant than Merriam’s or Ord’s.


This is data from our long-term site. Photo credits: Merriam’s by Sarah Supp, Ord’s by Andy Teucher via, Banner-tail by an unknown Portal researcher (i.e. we forgot to document who)

This all changes, though in the mid 1980s. Why? Blame Tropical Storm Octave which dumped nearly half of the annual rainfall in less than a week7. While the other kangaroo rats barely noticed this event, the Banner-tails hated it. Many individuals disappeared over the following months. The population tried to stage a comeback in the late 80s and early 90s, but like a one-hit wonder band, it fizzled. By the late 90s, the era of the Banner-tail was over. The last Banner-tail disappeared and there was much sadness among the researchers.

But you’ll notice some blips. Like a heart that beats irregularly, every few years a few little lost souls, wandering across the desert, find our site. Hopes and dreams of a new era of banner-tails spring anew only to be crushed by disappointment when once again they disappear.

Why did the Banner-tails disappear after Tropical Storm Octave and why can’t they seem to make it at our site now? It’s not entirely clear, but we think it has to do with shrubs. Banner-tails love grasslands. They don’t mind a scattered shrub here or there, but they don’t like too many shrubs 8. Sadly, since 1977, the site has become steadily shrubbier. Below are paired photos taken from approximately the same location at the site. On the left is Jim Brown on plot 4 in the late 1970s. On the right is 19959. Notice any differences? The Banner-tails definitely do!


All of this is ancient history. So why blog about it now? Because we are happy to report the return of the Banner-tail! Well, kind of. I mean, we currently have one lonely female – probably fairly young given her weight and state of her fur when she showed up. We’ve caught her 3 months in a row now on plot 11. The students have joked about setting up a twitter feed for her. Tweets suggested include:

“4 months since I left home. The food here is great and all the other mice are small and easy to fight off. I’m gaining lots of weight”

“Returning to my favorite bed and breakfast this weekend. Predator-free and good but monotonous breakfast. Four out of five stars”

“Young professional female spectab [shortened form of the species name of Bannertails] seeking like-minded male. Looking for something casual and fun, no relationship. Interested suitors should arrive at Plot 11”

Needless to say, we’ve been excited by the Banner-tail. Every month we’ve been wondering “Is she still here?” One day, probably soon, the answer will be no because our site is too shrubby for a Banner-tail to be happy there, but for now we dream of fields of Banner-tails.




  1. George Bartholomew and Herbert H Caswell. 1951. Locomotion in Kangaroo Rats and its Adaptive Significance. Journal of Mammalogy. Vol 32. Pages 155-169.
  2. Glen Bradley and Roger A. Mauer. 1971. Reproduction and Food Habits of Merriam’s Kangaroo Rat, Dipodomys merriami. Vol 52 Pages 497-507.
  3. Ana Davidson and DC Lightfoot. 2008. Burrowing rodents increase landscape heterogeneity in a desert grassland. Journal of Arid Environments. Vol 72 pages 1133-1145.
  4. How Shakespeare should have written the opening to Romeo and Juliet. (Sorry, Shakespeare).
  5. I had this data on hand and was too lazy to update with the newest data
  6. How do we figure out energy use? We estimate it from metabolic rate. There is a well known relationship between the size of an individual and its metabolic rate – larger individuals have higher metabolic rates (i.e. they require more food per unit time than smaller organisms). We used an equation for the relationship between metabolic rate and weight that was calculated for wild rodents to figure out the metabolic rate for each individual and then summed across all individuals of the species.
  7. Thomas J. Valone, James H. Brown, Carrie L. Jacobi. 1995. Catastrophic decline of a desert rodent, Dipodomys spectabilis: insights from a long-term study. Journal of Mammalogy, vol 76, pages 428-436.
  8. Peter M. Waser and James M. Ayers. 2003. Microhabitat use and population decline in Banner-tailed Kangaroo Rats. Journal of Mammalogy vol 84. Pages 1031-1043.
  9. I keep meaning to take a recent version of this, but haven’t remembered to do this when I’m at the site.

Another Source for Portal Project Related Posts

April 16, 2015

We have plans to write about some cool things going on at Portal right now: changes in the treatments at the site, beautiful winter annuals, some changes in the rodent community. In the meantime, I thought I’d point people towards Pacifica Sommer’s blog. Pacifica is a PhD student at the University of Arizona who has been using camera traps to study rodents. She’s been coming out to the site regularly to set up camera traps on our plots to compare what her camera traps are seeing with what our live-traps are catching. Her videos are a real treat and we’ve been luck to have Pacifica coming out to the site. She occasionaly writes about her Portal adventures on her blog. Here are some of her Portal related posts:

I have heard the howling of the grasshopper mice

Footage of the Mighty Predator: Onychomys torridus

Energy, Temperature, and Sex

Energy and Sexual Activity


The Portal Project Phase 2: Coming Soon

March 18, 2014
Winter annuals from 2012(?). Beautiful blooms like this seem to be an increasingly rare sight!

Winter annuals from 2012(?). Beautiful blooms like this seem to be an increasingly rare sight!

Stay tuned. The Portal Project blog is coming back on line with new material and new contributors! We’ve been busy at the site with some cool results and a new grant to fund new directions. We’ll start posting about it all soon. For those of you who follow this blog, previous contributors Sarah Supp and Glenda Yenni have both graduated, though they are both still working on Portal projects and come back to the site from time to time! Erica Christensen has taken their place and plans to post regularly about what’s going on at the site. In the meantime, let this beautiful picture by Glenda in the Portal archives suffice until we finish writing up some new material for the blog!


Portal at ESA 2011

August 4, 2011

If anyone still reads this blog, you may be wondering whatever happened to Portal. Well, rumors of our demise are…mildly exaggerated. Since I last blogged here, intrepid volunteers stepped forward and helped keep the project running on fumes. If you’re a Portal fan and you’re going to be at ESA this year, you should give the following people a hearty pat on the back (or better yet, buy them a beer): Kate Thibault, Karen Mabry, and Sarah Supp  (Glenda Yenni  is also on this list, but she won’t be at ESA this year, so you can just toast her in absentia). From May-December  of last year, we held things together with spit, duct tape, and fervent wishes. I even funded one of the trips by selling  a bunch of books to those used textbook people who seem to habitually lurk  the halls. Fortunately, Mother Nature was working with us and rodent numbers were so low that we could scale back our trips to every other month because rodent pressure on the exclosures was very low. Then the funding deities took some pity on us and we were awarded a 2 year NSF grant to keep the rodent side of things running. We’re still operating on some spit and duct tape, but we’re no longer hyperventilating. The plant side of things are a little more dire, but we’re all doing what we can.

Things at Portal are so not dead, in fact, that we have 4 different Portal presentations occurring at ESA this year. If you’re interested in hearing what’s been going on at the site stop by the following talks/posters (with short promos taken from their abstracts):

Tues: Multi-decadal climate cycles and the dynamics of a Chihuahuan Desert ecosystem. Morgan Ernest, Thomas Valone, James Brown. Poster Session 4:40-6:30 PM in Exhibit Hall 3, Convention Center

One of the greatest challenges facing ecology is understanding shifts in ecosystems that are being reported across the globe. However, understanding whether a particular shift in an ecosystem is the result of directional anthropogenic influences is complicated by the discovery of long-term climate cycles, such as the Pacific Decadal Oscillation (PDO), that fluctuate between alternative phases on decadal timescales. Because many currently operating long-term studies were implemented in the 1970s, 1980s, and 1990s, many of these studies have collected data only under one phase of these decadal-scale climate cycles, making it unclear whether the long-term trajectories documented in some ecosystems represent long-term lagged responses to large-scale shifts in climate due to naturally occurring climate cycles.

Thurs: Small mammal activities decrease soil organic carbon storage in dryland ecosystems. Jane Smith, Heather Throop, Thomas Valone, Morgan Ernest, James Brown. New Mexico State University. 8:20AM Ballroom F, Convention Center

Most of what we know about the terrestrial carbon (C) cycle comes from research conducted in mesic systems and dryland C cycling dynamics are more poorly understood.  However, arid and semi-arid systems cover 40% of Earth’s land surface and may provide an important C sink that will help mitigate the accumulation of CO2 in the atmosphere.  In drylands small mammal disturbances such as digging and burrowing can affect a large proportion of the surface soil, and these disturbances have the potential to influence inputs to and stability of the soil organic carbon (SOC) pool.  We asked how small mammal activity affects SOC pools in dryland ecosystems. 

Thurs: Experimentally altering biotic interactions has different effects on static and dynamic macroecological patterns. Sarah Supp, Xiao Xiao, Morgan Ernest, Ethan White, Utah State University. 4:00 PM Rm 8, Convention Center.

A major focus in recent ecological research has been to elucidate if and when the details of biological interactions play a critical role in producing observed patterns of diversity.  Macroecology has increasingly become an important and popular approach in ecology. However, because it often ignores the inherent complexity within biological systems in its attempt to find generality across systems, its utility has been increasingly questioned. This has generated an important question: are macroecological patterns contingent on the specific networks of interactions among ecological particles or do patterns emerge from interactions regardless of the details of interactions?

Friday: Decline in biotic resistance and the reorganization of an annual plant community by an exotic invader. Ginger Allington & Thomas Valone, Saint Louis University. 8:00 AM Rm 10A Convention Center

Species interactions are considered an important mechanism that limits the abundance and distribution of exotic species, a process known as biotic resistance. Many studies documenting strong biotic resistance have been conducted over short time scales. However, given time-lags inherent in exponential growth and natural population fluctuations, the strength of biotic resistance may change over time.  Here, we use a thirty-year dataset to show an eventual decline in the strength of biotic resistance.

The Portal Project is Dead, Long Live the Portal Project

June 4, 2010

As some of the people who read this blog are aware, Portal has been having trouble getting refunded. We are sad to announce that our most recent attempt at NSF LTREB funding was declined. These are difficult funding times for many of us and we know many people are experiencing similar difficulties to those we are currently facing. What this means for us is that Portal is now completely unfunded and thus the study will enter a new phase of existence. We’re still trying to figure out what this means for the project in a big picture sense. What is easier to answer is: What does this mean for the continued collection of the data? Morgan is committed to maintaining some level of data collection on the rodent community, but does not have the funds to do so on the monthly basis conducted for the past 30+ years. While we are still working out what is possible given our resources, for the next year we will probably start collecting data every 3-4 months and depend entirely on volunteer labor (we have depended on graduate RAs for data collection in the past). This means that at least some of the valuable information available from the time-series will continue to be maintained.

However, the maintenance of the experimental plots is dependent on monthly trips to trap out the exclosures and maintain the fences. Rodents are tenacious creatures and the desert is a harsh environment on man-made structures. Without this constant attention rodents will invade the exclosures. Since we have never had a 3-4 month gap in trapping before, we don’t know what effect this will have on the integrity of the experimental manipulations, but we doubt it will be “good”. At this time, there are no resources to continue data collection for the plants and ants. Obviously, in a big picture sense, this means big changes to the study.

We appreciate the support many of you have given us while we have been struggling over the future of the study. Suggestions such as renaming the Portal Project the “Bill Gates the Beneficent Long-term Desert Ecology site” in the hopes of attracting a patron have been much appreciated.

We have some future posts planned highlighting Portal papers that will be coming out this year and an update on what’s been going on at the site as of the May census, but I’d like to leave this post with the two reasons I think Portal is so wonderful and why I am so saddened by the choices we are facing:

1) Portals Contributions to Ecology.

  • Number of Papers/Books using data collected at the site to date: at least 112 and still counting (because so many people have worked at the site in so many capacities we have probably missed some; this number includes 28 papers in Ecology, 8 in American Naturalist, 4 in Ecology Letters, 3 in PNAS and 7 in Science).
  • Number of Graduate Students trained by the project: 20 (many of whom are currently faculty or government scientists).
  • Number of volunteers who have helped with data collection: Too many to count. Over the course of just the recently expired grant, over 60 people volunteered their time to assist with data collection at the site. These people included graduate students (both in ecology and in unrelated areas such as history and chemistry), undergraduates interesting in gaining field experience (including a wonderful young man who had never been out of Utah, never seen a palm tree before, definitely never been anywhere as hot as Portal, never seen a rodent outside of a pet store and never had an avocado before… he had the time of his life), postdocs and faculty interested in seeing a field site they had read so much about, and nonacademics ranging from school teachers to physical therapists to artists to lawyers who came for a wide range reasons, saw a little ecology in action, and spent the night under the most glorious view of the Milky Way.

2) Which brings me to the second reason Portal is so wonderful. Unfortunately, there are no words adequate for this, so I’ll let Portal speak for itself:


If you’re interested in helping with the site or just want to see some of our less… conventional… ideas for keeping the site going, please visit or email Morgan at:

Portal Data Published!

November 24, 2009

This announcement is a little late, but I’ve been a little distracted by my other baby (a biological one instead of a scientific one). But I am proud to announce that this summer the Portal Project data (ants, plants, rodents, and precipitation for 1977-2002) were published on Ecological Archives!! We’ve been working on getting the data in publishable form for several years now – doing a thorough quality check, writing over 90 pages of metadata, etc. We hope many more people will find this data as useful and fun to work with as we have! As long as the site is running, we will continue to publish new data through Ecological Archives every few years. Go enjoy!

Grassy, but not too grassy

September 8, 2008

Reports coming from the field crew for the August census indicate a lot of grass again this summer, but perhaps not as much as last year. The grass cover makes the rodent crew a little nervous about not being able to see where they put their feet (love those rattlesnakes), but it does make for some beautiful pictures of the site.

Plot3_wavinggrass_29 Aug 08_aernest Photo: A. Ernest

Above is a picture of plot 3 (a kangaroo rat exclosure plot), showing grasses rippling in the breeze.

Below is a picture taken from outside Plot 1 (control plot) looking in. The dirt in the foreground is one of the paths around the site. The fact that you can still see dirt is why the crew thinks there is less plant cover this year than last year.

Plot1_northfence_29 Aug 08_aernest Photo: A. Ernest

July Rodent Census

August 28, 2008

The remanents of hurricane Dolly hit the site last month while the trapping was occurring, so our numbers were probably low because the weather was bad. However, we still caught 1 of the 4 tagged Dipodomys spectabilis that are currently residing on the site. We go back down very soon, so we should have a better feel for what the rodents are actually up to.

Portal Project Poster at ESA

August 1, 2008

If you’re interested in what we’ve been up to lately, we’ll be presenting a research poster at next week’s Ecological Society of America meeting. The title is:

Effects of species identity and functional group richness on community structure and function: Are species functionally redundant?

by Katherine M. Thibault and S.K. Morgan Ernest.

It’s our latest work on the the invasion of Bailey’s pocket mouse (see photo below; isn’t he cute?) on ecosystem structure and function. So stop by Weds night and we’ll tell you all about what this little guy has been up to!


Photo by Katherine M. Thibault

An unexpected visitor

July 28, 2008

We occasionally catch non-rodents in our Sherman traps, but this month the crew caught something new. A toad!Portal 1 26July08

Maybe he saw all the rodents going into boxes and thought he’d see what the fuss was all about. The crew released him and he went on his merry way….probably with a lower opinion of rodents!

Portal 2 26July08

Expect more updates from this month’s rodent trapping as we process all the events!

Pictures taken by A. Ernest.