It’s Alive! Look Inside Our Giant Pandas’ Favorite Food

Panda Cam caught Bai Yun this morning demonstrating her bamboo-eating skills.

Panda Cam caught Bai Yun this morning demonstrating her bamboo-eating skills.

I had the privilege of interviewing Dr. Jennifer Parsons, an associate nutritionist at the San Diego Zoo. Although she manages diets for all of the animals at the Zoo, her specialty is a particular diet for a highly specialized species: bamboo makes up 99 percent of a wild giant panda’s diet.

A wild giant panda may roam the bamboo groves of China all day eating 25 species of bamboo, but not a zoo panda. The San Diego Zoo’s Horticulture Department grows bamboo for the giant pandas in the San Diego Zoo Safari Park’s parking lot. Every day, the horticulturists harvest the bamboo with chain saws coated in peanut oil, which is edible, unlike grease. After harvesting, they truck it to the Zoo’s panda exhibit, where it’s put in large coolers to wait for panda mealtime.

The keepers feed the giant pandas three times per day. At each feeding the pandas are offered twice the amount of bamboo that they will actually eat. This allows the pandas to selectively “sniff test” the bamboo, as they would in the wild. The pandas spend the entire interval between feedings processing and eating bamboo.

Bamboo is a colonial organism. An entire bamboo grove behaves likes one organism, which presents challenges for the Horticulture Department. Bamboo is actually a type of grass, and it’s the fastest-growing plant on Earth. Bamboo can grow up to 98 inches (249 centimeters) in 24 hours!

Bamboo has a seasonal cycle that determines where the plant’s nutrients are stored. This cycle may drive a giant panda’s preference for the leaves or the culm, the woody central stalk of the plant. In the winter and spring, when temperate bamboo produces shoots, nutrients are stored in the culm, so giant pandas favor this protein-packed stalk. When bamboo grows new leaves in the summer and fall, photosynthesis stores sugar and protein in the leaves; therefore, the giant pandas prefer the nutrient-rich leaves.

In the wild, pandas only eat temperate bamboo, so a wild giant panda’s home range is larger in the winter, giving the panda access to more food. But zoo pandas cannot seasonally change their territories, so the keepers feed both tropical and temperate bamboo species to the pandas at the San Diego Zoo. These bamboo species have opposite reproductive cycles, so the pandas can eat leaves and culm year-round. Strangely, however, both adult giant pandas at the Zoo, Gao Gao and his mate Bai Yun, prefer to eat the hard culm year-round instead of the easily digestible leaves. Pandas are a puzzle!

Pandas aren’t the only ones that use bamboo. In the bamboo forests of China (and at the San Diego Zoo) red pandas, takins, and golden monkeys also eat bamboo. Asian cultures use bamboo for food, medicine, construction, clothing, paper, musical instruments, bicycles, and fishing rods. Bamboo is also being used as a green resource all over the world. For example, the building housing the San Diego Zoo Institute for Conservation Research is built from sustainable bamboo.

Take a shoot out of a giant panda’s book and buy environmentally friendly bamboo products. And be sure to say hello to giant pandas Gao Gao, Bai Yun, and juvenile Xiao Liwu at the San Diego Zoo or on Panda Cam.

Elise Newman is a Caravan Safari guide at the San Diego Zoo Safari Park. Read her previous post, Northern White Rhinos in Peril.


Drought: Reptiles Don’t Like It, Either!

A cell phone photo taken of the habitat at the Safari Park Reserve in August 2014 shows just how devastating the drought has been on our local habitats.

A cell phone photo taken of the habitat at the Safari Park Reserve in August 2014 shows just how devastating the drought has been on our local habitats.

The drought has been awful for Southern California residents: dry, hot days, water restrictions, and a brown landscape. These are things we can all live with, but for our resident native reptiles and amphibians, drought can be a life-or-death situation. I have been working in the San Diego Zoo Safari Park’s Biodiversity Reserve (a 900-acre area adjacent to the Safari Park) for 15 years studying the reptile and amphibian species that call it home. This year I began a project studying a relatively rare coastal sage scrub species, the coastal patch-nosed snake Salvadora hexalepis virgultea. My plan was to capture at least 10 animals and implant them with radio transmitters so I could follow their movements and study their ecology. On normal rainfall years I see an average of eight of these wonderful snakes, so I figured that if I actively searched for them, I would be able to get a good sample size to study. However, I did not count on the drought being so intense.

Snakes get most of their water from the food they eat, and when there is no water, the food disappears as well. Many of our small, native animals tend to stay underground during such “tough times” and await better weather. Not only did many of the prey species disappear over the spring and summer, but the snakes also stayed deep underground to conserve moisture. Some snakes and other reptiles came to the surface for a brief period during the breeding season (April through June), and I was able to find a couple of patch-nosed snakes for my study. Unfortunately, reptile activity ceased altogether soon after. On a good spring day in a year with normal rainfall, I can find up to 20 snakes belonging to 8 to 10 different species in a single day. This year, in stark contrast to normal expectations, my best snake day yielded just two snakes. In addition, I spent nearly every day in the field for seven weeks in May and June and only saw two rattlesnakes. As the summer progressed and the habitat became more and more dry, very little lizard and snake activity was observed.

A red diamond rattlesnake found during a cover board array survey in 2010 at the Safari Park Biodiversity Reserve shows how lush and green the hills were that year.

A red diamond rattlesnake found during a cover board array survey in 2010 at the Safari Park Biodiversity Reserve shows how lush and green the hills were that year.

August is often our driest month, so we rarely see many animals in the field at that time. We often wait until late September before we start seeing hatchlings and juveniles along with occasional adult animals. This year, the young snakes have been virtually nonexistent, and that makes sense. If the adult female snakes and lizards cannot gain enough body mass, they generally will not reproduce. Since most of our wild animals stayed underground for much of the year, they probably did not feed and therefore were unsuccessful in breeding.

Last week I saw firsthand how difficult the drought has been on our native snakes. While walking through the coastal sage, I found a large, female red diamond rattlesnake Crotalus ruber. She was very thin and could barely move. I presume she had recently given birth (rattlesnakes in San Diego County give birth to live young in August and September) and just did not have enough body mass to make it through her pregnancy. No baby snakes were found in the vicinity, and I can only hope this female pulls through. If she had babies, they will, hopefully, be able to hold out until the rains eventually arrive.

A cell phone photo shows an emaciated red-diamond rattlesnake at the Reserve in September, 2014. Many of our local reptiles and amphibians are suffering from the recent drought.

A cell phone photo shows an emaciated red-diamond rattlesnake at the Reserve in September, 2014. Many of our local reptiles and amphibians are suffering from the recent drought.

In over 30 years of field “herping” (searching for reptiles and amphibians), I have not experienced drought conditions worse than those seen in 2013 and 2014. In fact, the North American Field Herping Association has shown just how bad the drought has been on Southern California snakes. When comparing non-drought year data from July 1, 2010, to June 30, 2012, with drought year data from July 1, 2012, to June 30, 2014, for snakes found in Los Angeles, San Diego, Orange, San Bernardino and Riverside counties, 4,971 snakes (1,055 hatchlings) were found between 2010 and 2012 whereas only 2,888 snakes (680 hatchlings) were found from 2012 to 2014. It is also interesting to note that there were more contributors to the database in the latter years, so roughly half the snakes were found by considerably more field herpers in the drought years than in the normal rainfall years, and roughly half the hatchling snakes were found in the drought years than in the normal years.

Here's a portrait of a healthy long-nosed snake in the Safari Park Biodiversity Reserve in 2009.

Here’s a portrait of a healthy long-nosed snake in the Safari Park Biodiversity Reserve in 2009.

So what does this all mean? Nobody can be certain right now. We do know that our climate has boom and bust years and drought and rainfall totals are very cyclical for most areas of the world. However, our findings to date do suggest that climate change is occurring at a rapid pace, and we all need to do our part to protect the environment and our natural resources, especially the snakes!

Jeff Lemm is a senior research coordinator in the Behavioral Ecology Division of the San Diego Zoo Institute for Conservation Research.


Bear Ambassador Learns Importance of Plants

Ambassador Mi Ton Teiow explores some bamboo growing at the San Diego Zoo. This bamboo represents the incredible horticultural collection of San Diego Zoo Global and a key component of giant panda habitat.

Ambassador Mi Ton Teiow explores some bamboo growing at the San Diego Zoo. This bamboo represents the incredible horticultural collection of San Diego Zoo Global and a key component of giant panda habitat.

We’ve mentioned in previous Bear Blog posts that some of the major threats to different bear species are habitat loss, or habitat degradation, or habitat fragmentation. As you can tell, for bear conservation it’s important to consider the amount and quality of bear habitat. For food, bears (except for polar bears) rely on plants. Thus, people concerned about bear conservation often become concerned about the conservation of the plant communities on which the bears depend. Although San Diego Zoo Global is involved in conservation of animals, it also does a lot of work with plants.

Recently I talked to botanists and horticulturists at the San Diego Zoo, and our whimsical Bear Ambassador, Mi Ton Teiow, was able to visit plants from bear habitats around the world. You might know that our horticultural staff grow most of the bamboo eaten by the giant pandas or the eucalyptus eaten by the koalas, but that’s just the beginning of what they do! I knew that certain parts of the Zoo contained plants related to some I’d seen in Andean bear habitat in the cloud forest of southeast Peru, but our horticulturists pointed out close relatives of plants that are important to Andean bears in the dry forest of northwest Peru, as well as plants from Australia, Hawaii, and Africa.

This flowering powder puff tree (Calliandra haematocephala) may catch your eye, but there’s more to the plant collection than what meets the eye.

This flowering powder puff tree (Calliandra haematocephala) may catch your eye, but there’s more to the plant collection than what meets the eye.

One reason they are able to grow such a diversity of plants at the Zoo is its variation in topography, which helps create a wide range of microclimates. I was surprised to learn that during winter, certain parts of the Zoo may receive frost at night! Of course, another reason the horticulture staff is able to grow such diverse plants is their research to understand just what the different plants need to grow and reproduce. Sometimes this research requires them to conduct experiments such as those in the lab to determine the best conditions for propagating orchid seeds, or field trips like those to investigate wild fig trees.

San Diego Zoo Global grows plants for many different reasons, and sometimes because the plants themselves are of conservation concern, plant species can be endangered, and captive reproduction can be an effective tool for plants as well as animals. In addition to plant conservation efforts, horticulture staff grow plants for several reasons related to animal husbandry. As I mentioned earlier, some plants are fed to the animals, providing them with more natural sources of nutrition than they would get otherwise. Parts of other plants are given to animals as a form of enrichment, especially because of their scents. When an animal shreds a few branches it’s been given, the animal is performing a natural behavior in a renewable manner: the horticulture department will grow more!

This diversity of plant species and structure may resemble tropical bear habitat, but it’s actually part of the horticultural collection at the San Diego Zoo.

This diversity of plant species and structure may resemble tropical bear habitat, but it’s actually part of the horticultural collection at the San Diego Zoo.

Woody plants are also used as structures in the animal enclosures. Large limbs, logs, and sometimes stumps are placed so that animals have items to rub on, climb on, and sometimes sleep upon. You can probably see our bears interacting with their log “furniture” any time you visit the Zoo. And, any time you visit, you can pick up a free map and take yourself on a self-guided walking tour of the botanical collection surrounding you. If you’re able to visit the Zoo on the third Friday of a month, you can explore the plant collections further. On those Fridays, called Plant Day & Orchid Odyssey, you can take a free narrated botanical bus tour to learn more about the plant collections, and you can visit the orchid greenhouse, which is home to more than 3,000 orchid plants!

The next time you’re visiting the San Diego Zoo or Safari Park, or a zoo elsewhere, take a closer look at the plants; they’re a whole lot more than “just” landscaping; they’re food, furniture, and enrichment for the animals and plant ambassadors of the habitats on which their wild relatives depend.

Russ Van Horn is a scientist with the San Diego Zoo Institute for Conservation Research. Read his previous post, Bad News Bears.


Beware of Crunchy Figs!

Here's a Moreton Bay fig fruit sliced in half.

The fruit of a Ficus sansibarica provides a cozy home for fig wasps.

Recently, the Wildlife Disease Laboratories received an interesting request from Seth Menser, a senior horticulturist at the San Diego Zoo, asking if we could take pictures of plant parts under the microscope. “I would really like to do a couple of shots of a fig cut in half with the fig wasps still inside. I have the figs needed for the shots. And, if you have never seen inside a fig, with the fig wasps, it is a very incredible thing to look at!” We were curious, so agreed to help.

Fig wasp

This amazing view of a fig wasp was taken in our Wildlife Disease Laboratories.

Seth brought up several figs from a Ficus macrophylla, commonly known as a Moreton Bay fig. These trees originate in the subtropical rain forest of eastern Australia but do well in frost-free climates such as ours. These majestic trees can reach up to 200 feet (60 meters) with long, aerial roots providing the tree with additional support to hold up the immense canopy. Seth brought several figs ranging from green and firm to dark maroon with spots on the outside. He explained the life cycle of the fig and the fig wasp as he cut them in half, and we set up the cameras.

Here's one

This female fig wasp has her wings. Is she ready to fly to a new fig?

Ficus trees are unique because the flowering parts of the plants are inside the fruiting parts (figs), making it difficult for insects to pollinate the trees. Thus begins the cooperative relationship with the fig wasp. The fig provides refuge and a food source for the wasps, and, in turn, the wasps pollinate the tree.

To begin the cycle, a tiny female fig wasp enters into a narrow opening (ostiloe) at one end of the fig. While wiggling into this small hole, she often looses a wing or antenna. Safely inside, she lays her eggs. As she is wandering through the fig, she spreads pollen from the fig she hatched in, thus helping the fig tree produce viable seeds. The cycle of the female wasp is complete, and she dies. Her eggs hatch, and the young wasps grow, finding food and refuge in the fig. Interestingly, only female wasps grow wings and leave the fig. The males live their entire life in the fig. Their function is to mate with the females and chew small openings through the fig’s wall for the females to escape, and the cycle begins again.

How many fig wasps can you find in this fig?

How many fig wasps can you find in this fig?

We were totally fascinated by the story. Using a dissecting scope with a camera attachment and a macro lens on a photo stand, we were able to capture the intertwined life cycles of the fig and the wasp. We photographed the narrow ostiole of the immature smooth fig where the female enters. Mature figs looked completely different on the inside. They were soft and fleshy, with delicate flower structures and seeds lightly attached to the inner walls. Each mature fig contained several wingless male wasps, and Seth was lucky enough to find one female flighted wasp.

At first glance, theses tiny wasps are difficult to see. The magnification helps, but a keen eye is needed to see them. How many can you find?

April Gorow is a senior pathology technician with the San Diego Zoo Institute for Conservation Research. Read her previous post, We Never Stop Learning.


Favorite Andean Bear Food: Sapote

Some of these sapote flower buds may develop into food for Andean bears, Sechuran foxes, and other wildlife.

Some of these sapote flower buds may develop into food for Andean bears, Sechuran foxes, and other wildlife.

In conservation research, we’re often interested in measuring variation across space and time, looking for patterns in that variation and deriving explanations for those patterns. However, during my last trip to the field, I found myself pondering changes over time on a much longer scale, across over 1,000 years. As I walked under the hot sun dragging a tape measure through the brush day after day, and I started stepping over ancient stone walls, it was easy to start wondering about the original purpose of the walls, even though that had nothing to do with the task at hand!

What I should have been totally focused on was making sure that we were correctly measuring the distances between trees in the tropical dry forest of northwest Peru. As part of the Andean bear conservation program, I was there working with the Spectacled Bear Conservation Society and with local citizen scientists (see post Citizen Science: Engaging People in Conservation Research). With support from the Disney Worldwide Conservation Fund, Samantha Young and I have been developing several initiatives to engage local people in conservation science and action (see Scientific Concepts for Non-scientists). One focus of my trip was to train citizen scientists in collecting data from woody plants, because we’re interested in knowing more about how plants that are important for Andean bears vary in space and time. In particular, we’re interested in understanding the variation in when and where sapote produces flowers and then fruit, because sapote fruit appears to be the critical food source for Andean bears in the dry forest of northwest Peru (see Andean Bears: A Surprising Discovery).

To get information on the sapote population, we measured little trees...

To get information on the sapote population, we measured little trees…

Although sapote is considered critically endangered, there have not been many studies done on its reproductive ecology, so we can’t simply visit a field site and estimate how much fruit the sapote trees there might produce or how many bears might be supported by those trees. So, our goal is to collect information every month, such as which trees have flowers, which trees have fruit, and the condition and size of those fruit. Because we don’t have any background information on these sapote trees, we’re going to learn something new practically every month. For example, during our first data-collection period we discovered some individual sapote with a few ripe fruit left from this past season and several new flower buds. I had no idea that the same tree might have both flowers and fruit at the same time!

...and we measured big sapote trees.

…and we measured big sapote trees.

Another new observation with more serious implications for bears and other wildlife that feed on sapote fruit is that sapote grows only in a narrow band on the lower slopes of the hills at the edge of the valleys. We knew this generally, but we had never measured the width of this strip; it’s much narrower than we thought, meaning that there’s less area covered by sapote trees than we expected, and, presumably, fewer sapote trees. Over the next several months, we’ll begin to get an idea of how many flowers and fruits those trees produce and how that production varies depending on characteristics of the sapote trees and the places where they’re living.

Although we’ll be looking at variation in flower and fruit production across relatively small-scale changes in space and time, especially in comparison to the scale of the landscape and the scale of human history in this area, these are the data we’ll need to understand variation in sapote and in Andean bear ecology.

Russ Van Horn is a scientist in the Applied Animal Ecology Division of the San Diego Zoo Institute for Conservation Research.


Rain in the Mojave Desert

A desert tortoise prepares to snack on a desert mallow.

When most people think of the desert, they don’t think much about rain. Well, on August 22, the Mojave Desert experienced record-breaking rainfall, with some areas receiving well over 2.5 inches (6 centimeters) of rain within a 24-hour period, which caused major damage to the area. Most damage was due to washed-out roads and to low-lying property. But altogether, the desert had a much-needed drink for such a hot and dry summer.

Desert plantains have sprouted after record rainfall in the Mojave.

The aftermath of so much rain caused an explosion of plant life to appear throughout the desert. Some plants had not been seen in certain areas for many years. Plants such as the desert plantain Plantago ovate, desert mallow Spaerlcea ambigua, and golden bush from the genus Ericameria, just to name a few, started growing all over the desert. These plants are some of the desert tortoises’ favorite foods, which will help them have a full stomach before they go down for hibernation in the winter.

Daniel Essary is a research associate at the San Diego Zoo’s Desert Tortoise Conservation Center. Read his previous post, Rabbits, Rodents, and Tortoises.


The Right Tools

Two boys admire aguaje fruit, an important resource in the Peruvian Amazon.

Sometimes all you need is the right tools.

In August 2010, I spent three weeks trudging through swamps in the Peruvian Amazon to assess the aguaje palm population on the lands of an indigenous group known as the Maijuna. Aguaje is an avocado-sized fruit with smooth scales covering a thin layer of bright orange flesh. It is high in Vitamin A and very popular in the large Amazon city of Iquitos. As a result, rural communities from all over the region, including the Maijuna, harvest aguaje to supply the city’s demand. But the tree’s height (up to 90 feet or 27 meters!) means that the fruit is often harvested by cutting the palms down.

Aguaje fruit awaits buyers in the market place. It is spread out so shoppers can assess the quality.

The extreme heights are also difficult to measure, and attempting to do so in the boot-suctioning mud of the swamps wasn’t always easy for us in the field. But the animals don’t mind: a plethora of wildlife, including monkeys, parrots, tapirs, and peccaries, are known to frequent the aguaje palm swamps to feast on the fruits.

While I was in the swamps, Michael Gilmore of George Mason University conducted interviews with Maijuna villagers. The objective of our combined work was to better understand the management needs of aguaje. A few years ago, the Maijuna decided to reclaim sovereignty over their natural resources by keeping outsiders, especially loggers, from coming onto their lands and better managing their own use of the land’s resources. This included finding a better way to harvest aguaje without killing the palms, and some of the community members learned to use climbing harnesses to reach fruit at the top.

A group of community members shows off their new climbing harnesses. Every household with a member attending the workshops received a harness.

But not everyone could climb. What Michael found out in the interviews was that, for many families, no one knew how to climb, so some continued to harvest the old-fashioned way, with an ax, even though they knew of the consequences. Even people who knew how to climb would sometimes use axes. What struck me, however, was how many families said they just stopped harvesting fruit because they didn’t know how to climb and wanted to conserve the palm trees. That is awesome! It shows a commitment to sustainable management and that the people place a high value on the future of the resource. But it also means those families are missing out on a potential source of income. When the average family income is just over $500 a year, the few dollars made from selling some sacks of aguaje can make a big difference. This partially explains why some people continue to cut.

Key to workshop success was ample time for attendees to practice climbing. Practice allows people to become comfortable at the extreme heights needed to reach the fruit.

After our assessment in 2010, it was clear that the Maijuna needed more training. And more equipment. The 37 households in the 2 villages were sharing a handful of harnesses, and they weren’t always available when needed. So in 2011, we held climbing workshops and invited everyone from the villages. We shared our study results, but most people were already aware of the negative impacts of cutting palms. We focused on hopeful things: there are a lot of seedlings and saplings growing in the damaged swamps that will provide fruit in the future. And we gave the people a lot of time with the expert climbers. Everyone got to practice and get comfortable with the climbing harnesses. We also wanted every household to have the right tools, so every household received a harness.

We didn’t expect the workshops to solve everything. The stands of aguaje palm need to recover from the years of destructive harvesting. But things did improve—a lot. In 2012, we went back to evaluate. Even though many more families harvested and the community harvested 50 percent more sacks of fruit, the number of cut palms went down. And now, instead of over half of the palms harvested being cut down, only about 14 percent were. To me the encouraging sign is how many more families were harvesting fruit, now that they knew how to climb. Their willingness to restrain from harvesting before, even though they would have liked to, shows commitment to resource management. All they needed all along were the knowledge and the tools for better management practices.

That’s San Diego Zoo Global’s role in this project: trying to figure out the best tools for the community’s goals and help them obtain those tools. Next with aguaje, we’ll be working with the community to figure out the best ways to improve the stock of aguaje palms on their lands. We want to make sure there’s enough aguaje for both wildlife and people.

Christa Horn is a research coordinator in the Applied Plant Ecology Division of the San Diego Zoo Institute for Conservation Research. Read her previous post, A Grand Experiment for Palm Trees.


Maui Youth Lend a Hand

We thank the Hawaii Youth Conservation Corps for their efforts!

Sometimes we can all use a helping hand. Do you remember a blog about the battle we fight against the invasive plant known as gorse? (See Gorse Crisis: Making Way for Native Plants.) Well, the Maui Bird Conservation Center (MBCC) benefited from the generous efforts of eight hard workers from the Hawaii Youth Conservation Corps (HYCC). They battled for two long days against a particularly stubborn patch of over-grown gorse and then placed native plants in the cleared space.

As background, the nonprofit organization Kupu, which is dedicated to providing opportunities for the youth of Hawaii, operates the HYCC. Kupu offers Hawaii’s young adults the chance to gain job training and life skills such as leadership, communication, responsibility, and teamwork, while encouraging service within the community. During their summer program, high school students spend six weeks as Americorps interns, assisting in the protection of the environment while learning about natural resource management through projects such as trail maintenance, native plant restoration, and coastal restoration, plus many other experiences.

Young koa and uki uki plants have a chance to thrive now at MBCC.

A crew visited MBCC after working at various sites on Maui and Kahoolawe for projects with The Nature Conservancy and the Maui Forest Bird Recovery Project. Yet they still had the energy to tackle our gorse problem! Led by Christine Molina, the team leader who works as a teacher during the school year, the team of Carl, Issac, Kamana, King, Kyla, Pololou, and Stephanie split into two groups. As one group toiled away with saws and pruners to remove the gorse, the other team broke through the rooted soil with shovels to dig holes, which they filled from several large trays of native plants, donated by Anna Palomino, a local native Hawaiian plant expert who generously donates extra plants to MBCC. Their combined efforts made short work of an area that would have taken our MBCC team a month to clear and plant, with all of our other duties pulling at our attention.

Although the restoration area does not look especially spectacular now, with time and nurturing by the MBCC team, we hope the native plants will flourish and be a source of pride for the future, thanks to the wonderful and diligent work of the Hawaii Youth Conservation Corps.

Joshua Kramer is a research coordinator at the Maui Bird Conservation Center, operated by San Diego Zoo Global. Read his previous post, Hawaii: Native Birds and Plants.


Cactus Wrens Rise from the Ashes

Coastal cactus wrens build their nests in large prickly pear cactus. When cacti are killed by land clearing or wildfires, wrens have nowhere to nest.

After the 2007 Witch Creek Fire, which burned through the San Diego Zoo Safari Park and surrounding San Pasqual Valley, the outlook seemed grim for local populations of coastal cactus wrens. With populations already rapidly declining throughout Southern California, we all wondered if the fire, which heavily damaged critical nesting areas, was going to be one of the last chapters in an all-too-familiar story of species loss. A survey for coastal cactus wrens within the Safari Park Biodiversity Preserve shortly after the fire turned up only 10 pairs, further suggesting the population here was in a precarious position.

Even as the land smoldered, we began developing habitat restoration plans to help speed up recovery of native habitat. We focused on two critical coastal cactus wren needs: prickly pear cacti, which the birds need to nest, and native shrubs such as elderberry, buckwheat, and California sagebrush. Our goal was to enhance 45 acres (18 hectares) of habitat to support the recovery of wren populations and ensure the long-term survival of the species here in the San Pasqual Valley.

We have propagated thousands of native prickly pear cacti to support habitat restoration for cactus wrens.

Efforts began in 2008 and involved propagating and planting thousands of cacti and native shrubs across difficult, rugged terrain. Sometimes, the last four years seem like a blur of hard work, hot temperatures, sweat, blood (cactus spines hurt!), and more work. The effort, led by Sara Motheral and Colleen Wisinski, has been nothing short of amazing. We are nearing our goal! This year, we will complete the habitat enhancement of the 45 acres. Even more exciting is the fact that wren populations are rebounding—it is hard not to see or hear wrens calling while walking in the Safari Park Preserve.

Colleen Wisinski monitors a cactus wren nest, checking for eggs, at the Safari Park’s Biodiversity Preserve.

Even as we approach one milestone in the project, we are already expanding our efforts beyond the Preserve and have begun developing habitat restoration plans throughout San Pasqual Valley to connect isolated populations of wrens and create new habitat patches. It is only a matter of time before the next wildfire happens, and the long-term survival of the wrens depends on having high-quality habitat within the Preserve and throughout San Pasqual Valley.

To this end, we are already propagating cacti to enhance an additional 50 acres (20 hectares) of habitat throughout San Pasqual Valley and utilizing advanced technology such as Geographic Information Systems, spatial analysis, and computer modeling and simulations to help us determine high-priority locations for habitat restoration efforts to maximize the probability of success. No rest for the weary!

Bryan Endress is the director of Applied Plant Ecology for the San Diego Zoo Institute for Conservation Research.


Gorse Crisis: Making Way for Native Plants

Amanda and Amy remove some invasive gorse.

It goes without saying that wild bird populations are dependent upon good quality, natural habitat for foraging, nesting, and escaping from predators, to survive. The native forest birds of Hawaii face a multitude of threats, and the loss and degradation of habitat is one of the primary reasons for the decline of these unique species. Invasive plants and animals are taking over and destroying their forest home. For example, introduced pigs and deer browse on the plants and churn up the forest floor in search of food, killing native seedlings and providing an opening for faster-growing, invasive plants to gain a foothold in native environments. In many cases, in order to restore native plants, we must first remove the nonnative ones.

Gorse in bloom. Note the nasty thorns!

Gorse is one such invasive plant common in parts of Maui as well as the Big Island. The dense, prickly shrub, introduced to Hawaii in the 1800s, originated in western Europe, where it is still valued as a living fence for livestock. In addition to its aggressive tendencies, gorse grows much more quickly than most of Hawaii’s indigenous species and easily out-competes them for space and sunlight. Today, gorse is considered to be a serious weed, and all attempts to eradicate it have failed. The International Union for Conservation of Nature recognizes gorse as one of the top 100 worst invasive species in the world; so far, the best-recognized method for combating gorse is to plant faster-growing plants that are able to shade out sun-loving gorse.

At the Maui Bird Conservation Center, we have our own gorse crisis. Fellow intern Amy Kuhar and I are tackling our gorse invasion head on. Because the gorse defends itself with innumerable thorny spikes, we have started by taking down different sections of the weed in phases. We start by trimming back branches with loppers, then we use hand saws to sever each plant at the base. When possible, we also dig out the roots. The process is very time consuming, and we have worked many hours on the project. “Painstaking” would be the best adjective to describe the effort, because the gorse fights back, and after an afternoon of gorse eradication, we are left with innumerable itchy, tiny thorns embedded under the skin of our hands, arms, and legs!

A mamane sapling planted at the MBCC.

In addition to rescuing resident koa, ‘ohia, and mamane trees choked by gorse around the facility, we also began the process of replacing the invasive vegetation with native plants such as `a`ali`i and more mamane. In one area alone, we have planted more than two dozen new trees and are excited to see them growing over the newly cleared area! But the battle does not end there. One of gorse’s greatest weapons is its massive production of seeds, which can lay dormant in the soil for many years. As the older gorse is cleared, the seeds rapidly germinate, and within a few weeks there is a bed of new gorse seedlings. To stay on top of these, we must spray with herbicide to prevent another new invasion, allowing the native plants to flourish.

Hopefully, future interns will continue to clear gorse to make way for more native planting, all of which will someday create habitat for our wild, feathered friends such as the `amakihi. We hope the native plants will also eventually provide a source of perching, nesting material, berries, and seedpods for the birds in our care.

Amanda Maugans is an intern at the San Diego Zoo Maui Bird Conservation Center.