Category Archives: Wildlife

Wrongfully Convicted – Life of a Banana Slug

Most gardeners hear the word slug and immediately have a negative thought about them being destroyers of their beautiful plants and I was guilty of this assumption too when I first heard banana slug.  In most cases they are a nuisance, but the Pacific banana slug (Ariolimax columbianus), along with its other two relatives, the California banana slug (A. californicus), and the slender banana slug, (A. dolichophallus), have a different role in the environment. Banana slugs are detritivores (decomposers) and thrive on dead plant material, mushrooms, animal droppings, moss, and leaves. They recycle these materials and help with the dispersing of seeds and spores as well as take part in creating nitrogen rich fertilizer. The dead organic matter they consume supports decomposition on the forest floors and aids in nutrient cycles.

Banana slug party on Alcatraz after the first rain. Photo by Caity Chandler
Banana slug party on Alcatraz after the first rain. Photo by Caity Chandler

Banana slugs are primarily found in the Pacific Northwest, ranging from southern California up to Alaska and are home to moist, temperate, forest floors.  They are the second largest slug in the world, reaching up to 10 inches (25 cm) in length and can live to be seven years old. They get their name because of their yellow coloring, resembling a banana, but can also take on dark spots or even become a little greenish. This is caused by a number of things such as their food consumption or the light or moisture levels they are exposed to and even the health of the slug. They have two sets of antennae that serve different purposes. The shorter set is used for sensory while the longer pair is used for sight.

Just a handshake today, no licking. Photo by: Shelagh Fritz

Just a handshake today, no licking. Photo by: Shelagh Fritz

One of banana slug’s unique characteristics is their slime.  Banana slugs are prey to raccoons, garter snakes, ducks, and geese, but their slime serves as an anesthetic to predators causing their mouth to go numb if they dare take a bite. The slime isn’t toxic to humans and people have been known to lick them to test the theory of the numbing sensation. I personally haven’t tried it, but know people that can attest to its factuality. Another benefit of the slime is its ability to help them retain moisture. Banana slugs are mostly water and are prone to desiccation. The slime actually helps attract water and has the potential to absorb up to 100 times the slugs water weight.  Slime also supports the banana slug’s mobility in navigating through the forest, gliding over dirt, leaves, and other debris.

Love at first sight. Photo by: Shelagh Fritz

Love at first sight. Photo by: Shelagh Fritz

Being new to the West Coast, I was unfamiliar with the banana slug’s positive influence on the forest floor and contribution to the soil. I thought they were a nuisance to the garden and plant life similar to other slugs, but in fact they are an important aspect of the ecosystem assisting in decomposition. The banana slugs still remain happy, innocent, inhabitants of the island. I was very excited the first time I spotted one and after I saw one, I must have seen 30 that day. Keep your eye out for these cute little guys on moist days and appreciate their positive impact in our beautiful forests. Hugs for slugs!

 

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A crime scene on Alcatraz

Seabird nesting season is in full force on Alcatraz. This wonderful time of the year is a rare chance to see many of the Bay Area’s seabirds nesting and raising their young. In numbers (and in volume) are the Western gulls. Last year they counted in at around 2000 pairs.

 

However, their arrival always comes with a bit of apprehension. The gulls of course need material to make nests and must also claim territory. Both of these tasks mean that plants are torn up and shredded, and all too often these are garden plants!

 

We have come to expect a bit of damage but with the native grass, Carex praegracilis, lawn that was planted with plugs we were a bit nervous if the plugs would take root and be strong enough to withstanding the tugging by gulls.

 

The plugs were planted at the beginning of November when the rains would hopefully start. While we had some showers we had to supplement with hand watering too from our rainwater catchment. About 1/3 of the lawn was planted and now 5 months along, the plugs have started to send out stolons and are spreading.

 

On a recent sunny morning, while checking the gardens over, I noticed a puzzling crime scene – the grasses were being shorn off close to their bases.

 

Carex plugs being nibbled to their bases. Photo by Shelagh Fritz

Carex plugs being nibbled to their bases. Photo by Shelagh Fritz

Guilty by past behavior, I immediately suspected the gulls. But, the telltale sign of shredded vegetation was not present. In fact, the missing tops of the grasses were actually gone! What could this be? We don’t have deer or rabbits and yet the grass looked ‘nibbled’.

 

Examining the scene closer, I spied the ‘evidence’ left behind – droppings. Sure enough Canada geese had found our lawn. There are maybe 3 pairs of geese on the island and they were making our lawn their morning buffet.

 

Canada goose 'evidence'. Photo by Shelagh Fritz

Canada goose ‘evidence’. Photo by Shelagh Fritz

For all of our planning and thinking of possible ‘what could go wrong scenarios’, we had overlooked the population of geese and their liking of grass.

 

Luckily, few plugs have been pulled out, the geese are proving to be more grazers, and hopefully the plugs will continue to grow. Mowing actually helps grasses get thicker and encourages them to send out more stolons.

 

The lawn is slowly being ‘mown’ from left to right, but at least the plugs are being fertilized too.

The native sedge lawn being 'mown' by Canada geese. Photo by Shelagh Fritz

The native sedge lawn being ‘mown’ by Canada geese. Photo by Shelagh Fritz

 

With the mandated 25% cut in water usage in California, I’m so relieved we choose to have a native sedge replicate the look of a lawn. Our ‘lawn’ will be low maintenance and will only require 2” of water per month to stay relatively green throughout the summer months.

 

As Alcatraz is a destination, I’m hoping that visitors will take notice of our drought tolerant lawn and ask questions. The lawn will also be a topic on our garden tours and offered as an alternative.

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Gardening with Gulls

Gardening on Alcatraz has many challenges – limited fresh water, harsh winds, chilly fog, and transporting  supplies to the island; but one challenge came as a surprise only after we had started planting in 2005 -the Western Gull. Actually 2000 of them. Victoria Seher, National Park Service wildlife biologist monitors their numbers: there were 740 nesting pairs in 2011, up from 722 pairs in 2010, but down from 1061 pairs in 2008. Each nesting pair usually lays three eggs, adding to the population substantially.

The first two years of the project, from 2003 to 2005, was intensely focused on removing overgrown vegetation built up from the 40 years of neglect. By 2005, the trough planter along the main roadway leading to the top of the island had been repaired and was ready to be planted. This was a significant event – the first planting in over 40 years! Staff and volunteers eagerly turned out that day to help plant the 330 feet of trough with ivy leaf geraniums, Pelargonium peltatum, that had originally filled the trough in the 1940s. Heirloom pelargoniums were sourced from Geraniaceae in nearby Ross, California and everyone pitched in for a fun day of planting. Standing back proudly at the end of the day, the accomplished work was admired. However, returning the next day, the plants were gone! Unwittingly, 330 feet of prime nesting material had nicely been laid out for the western gull.

Learning from our mistake, new plants are now caged – almost like being imprisoned themselves. We have become experts at building cages out of chicken wire. We have also learned to optimize the time the gulls are away from the island to give the plants the longest time possible to develop their own roots to help anchor themselves in the ground. Seabird nesting season is from February to September, so by October, we are ready for planting and the winter rains.

Cages protect succulents against the gulls. Shelagh Fritz photo

 

Seagull damage to daylilies. Photo by Marian Beard

Like other gardeners that square off against deer, I have noticed that certain plants seem to attract sea gull vandalism, while other plants go unnoticed by our feathered friends. Strap-like leaves beckon to gulls; I guess this material is easy to harvest and to shape into a nest. Beds planted with Bearded Iris, daffodils (Narcissus) and cottage pink (Dianthus plumarius) in the Officers’ Row gardens have been replanted with more hardy plants that can stand up better against the gulls. This year, the gulls have taken a liking (or dislike) to the beautiful daylily, Hemerocallis ‘Kwanso’. This is a triploid flowering daylily with tangerine colored blossoms. The gulls have nipped down the plants to the bases which will make flowering unlikely this year. However, the gulls that nest

An aloe completeley destroyed by gulls. Photo by Shelagh Fritz

on the west side of the island leave the cottage pinks and bearded iris alone and choose to peck the succulents instead. Tough aloes and aeoniums are shredded instead.

I have also learned a few interesting facts about the Western gull – they mate for life and that they come back to the same spot to nest year after year (up to 20 years is typical for a gull). Waging a 20 year battle against a bird seems a bit ridiculous so it is far easier to accept the gulls. When I started as the gardener in 2006, I took a strong dislike to the gulls, but now, they have really grown on me and I’ve actually gotten to know some of the gulls. There is a one-legged male in Officers’ Row that I try not to disturb so he doesn’t have to stand up. There’s also a whole gauntlet of gulls nesting along the road that leads to the rose terrace. A few years ago, anyone walking down this road was taking a great chance at being marked, but now the gulls barely glance at me when I walk by. However, anyone they don’t recognize gets the full squawking treatment. There’s also a pair that nests in a huge clump of ivy in the Inmate Gardens on the west side. Their young usually wander around the gardens and drink from our hose during the summer.

Come out and see the gardens and gulls this spring! Nowhere else will you be able to experience a major seabird nesting colony, historic gardens, and a former prison on an island so close to a major city. I’ll bet you will admire the gulls in a way you never did before – what took me 6 years to realize, will only take you an afternoon.

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