Friday, April 14, 2017

Arlington Bioblitz

Arlington's Bioblitz team from last year who assisted in the National Park Service Bioblitz


     Mark your calendars now. May 20th, 2017 is Arlington County's first Bioblitz, and you can participate and contribute. A bioblitz is a quick, but intense, biotic survey completed within a 24 hour period. Consider it a snap shot in time of what plants and wildlife are found in a certain place during that period of time. While this is certainly not a complete record of what lives there, it provides a vital look at what is there during that period. If you get enough snap shots, then you can get a clear picture of what's there. 
     The Arlington Bioblitz will kick off a much larger and longer survey of what we have in Arlington. Over at least a two year period, the results of this and even more surveys will help us know what we have, and compare it to what we have recorded before or what was historically present. This information will help shape the new update of the County's Natural Resource Management Plan. You can't manage and preserve what you don't know you have, so this info is vital. You can see the previous County Board approved plan here:  https://projects.arlingtonva.us/natural-resources-management-plan/  If you'd like to see the technical report (granted also in need of updating using new survey information) that resulted from our previous county biotic surveys, please check here: https://projects.arlingtonva.us/wildlife-arlington/  
     The Arlington Bioblitz will kick off many more surveys where we will check on previous records and see how those plants and animals are doing (and get an idea of how our Natural Resources Management Plan has done). But we will hopefully also find new flora and fauna that can influence what the new Natural Resources Management Plan update will include. Some of this will be done by County staff, some by contracted experts, and much more with the aid of volunteers and citizen scientists.
     This is where the general public such as you comes in. We hope you can join us that day (and stick around to help with the surveys that follow) to record what you see. Join Bioblitz survey teams in various County parks. Perhaps you have an expertise and can help lead a team. Perhaps you can help be an extra pair of eyes or help record what is seen. We plan to use the iNaturalist application to collect most of the data. This where regular folks along with experts can record sightings, often using a photograph that can serve as a voucher of what was seen and which can be verified by others. More on this neat process here: http://www.inaturalist.org/
     So what is planned for Arlington Bioblitz May 20th? Our field base will be at Barcroft  Park, one of several parks that we have planned for surveying. These parks also include Glencarlyn, Long Branch, Gulf Branch, Tuckahoe, Fort CF Smith, Bluemont, even our colleagues at Potomac Overlook will be hosting teams. 
     We have some experts that will be leading some very interesting searches for mammals, reptiles, amphibians, fish, macroinvertebrates, birds, plants, and some insects such as bees. Most of the teams will be conducting their inventories from 10am-4pm, but a few such as the birders will get an early start. Want to help conduct some citizen science that day and join us? Start by checking here: https://environment.arlingtonva.us/events/arlington-bioblitz-a-wildlife-and-plant-inventory/   We also have a kickoff event, explaining a bit more about what and why we are doing this and other biotic surveys scheduled for the evening of April 18th. You can find out more about that event here: https://environment.arlingtonva.us/events/plants-and-wildlife-of-arlington-county-bioblitz-kickoff-celebration/ .
     Want to lead a team or get even more info? Contact Arlington County Parks Natural Resources Manager Alonso Abugattas at either AAbugattas@arlingtonva.us or by phone at 703-2287742. Participating in a bioblitz is not only a lot of fun, but provides some valuable citizen science. Recording these nature discoveries helps us know what we have and how we can better protect them. But it is also a great hands-on way to learn from experts and one another, all in a social and and informative manner.

Friday, March 31, 2017

Spectacled Caiman


     I've been lucky enough to have had several encounters with Spectacled Caiman (Caiman crocodilus), the most recently on my trip to Central America. I've never seen so many as I have at Cano Negro near the Nicaraguan border. There were hundreds of them, specially emerging at night. Shining a flashlight on the water resulted in an incredible display of eyes glowing back at us. So I thought I'd tell you a little bit about them.


Caiman are nocturnal creatures

     Spectacled Caiman are the most abundant of all 25 of the crocodilian species. They're also called Brown, Common, or White Caiman, and have 3 subspecies. They range throughout both Central and South America. They've also been introduced (often as released or escaped pets) into Florida, Cuba, and Puerto Rico where they did not occur before.



     Spectacled Caiman do not get as large as other crocodilians. Males are larger and get to about 6.5 feet long. Females get to about 4.5 feet. They average 3-4 feet and 60 lb in general, but one was recorded at 8.2 feet and 128 lb. Their most common name comes from a distinctive bony ridge between the eyes which look like spectacles. Adults mostly have a grayish green coloration, but can get much darker during colder weather.


The bony ridge between the eyes give them their most common name: Spectacled Caiman

     Caiman have a varied diet, often depending on their own size and what's available. When small, they will eat insects, crustaceans, molluscs and other invertebrates. When they get larger, they prefer fish, but will eat waterfowl, mammals, and even each other. It's this generalized diet which has helped them to adapt to different habitats. They mostly feed at night. 


Spectacled Caiman are relatively non aggressive, even when surrounded by livestock.

     Though they may look intimidating, attacks on people are extremely rare, and when they occur, are almost always defensive in nature. In fact, they almost always flee when approached, as I know first hand. They do not even attack when you'd think they have a good reason to. I can give you 2 examples.
     On the first occasion, my wife Lucy and I were fording the Rio Frio on horseback. The water was about 3 or so feet deep when the horses were wading through, and we had to lift our legs to keep from getting too wet. Caiman, as usual, scattered as soon as we got close. At one point, Lucy's horse actually stepped on a medium sized caiman. The horse startled slightly and the caiman thrashed a bit as it swam away. Although it had every reason to bite, it never even tried to. 
    On another occasion, we were on a night excursion. We saw huge numbers of caiman every where. Our guide, one of the local cops, took us to an area used as a creche, a place where baby caiman all congregated for safety under the watchful eyes of female caiman. With our guide's permission, I caught a baby. I've handled crocodilians before and knew how to do so safely so as to not get bit. The little reptile though started squealing for help like they often do. Though this normally elicits a protective response, no mom showed up to defend it. Spectacled caiman really do try to avoid confrontation when they can.


A young caiman I caught protests loudly to my handling him.

     Female caiman are protective mothers however. Reaching sexual maturity in 4 - years, most caiman mate during the dry season. Females build nests during the wet season, mostly from vegetation, laying up to 40 eggs depending on the mother's size. The eggs hatch in 65-105 days, again heavily influenced by temperature. The decaying plant matter helps warm the eggs. Those eggs exposed to temperatures over 89 degrees Fahrenheit typically become females, lower than that and you get males.  
     The young are normally yellow in color with black spots. Babies congregate in certain areas in creches. Females take care of not only their own young, sometimes even carrying them on their backs, but of the others in the same area. Despite this excellent maternal care, predators such as tegu lizards, coati, and large water birds eat many of them.



     If they survive to adulthood, they are relatively safe from many predators. Though larger caiman, crocodiles, and jaguars take their share, man is their main threat. But because their skins have hard plates called osteoderms and their relatively small size, the market for their hides is much less pronounced than for other crocodilians. But the sides do yield some leather and hunting for food or out of fear does take place. Though their numbers are low in some countries such as El Salvador and Peru, in most others they are steady or growing. They are considered a species of least concern and in some places are legally harvested.


The American Crocodile riding low on the water is endangered world-wide, the Spectacled Caiman below it,with its protruding eyes, is the most common crocodilian. Crocs can get huge and will occasionally eat the smaller caiman.

     If nothing ends up happening to them, it is believed that they can live up to 75 years. Indeed, they have spread their range and are even considered invasive in such places as Florida and Cuba. The population in Florida really got established in 1992 after Hurricane Andrew allowed the escape of many captive specimens.
     But in their rightful environment, these are truly remarkable species, one that I always enjoy seeing in the wild. Here's a short video from the Capital Naturalist YouTube Channel showing them in Costa Rica: https://www.youtube.com/watch?v=mBGnt1RDSLw

How many Spectacled Caiman eyes can you count?

     For comparison, and much larger and rarer, here's a short video on my encoutnter with a Black Caiman while in a dugout canoe in Peru:
                                 https://www.youtube.com/edit?o=U&video_id=kO_lF7UkRi8

Monday, February 13, 2017

Carolina Wren



     Carolina Wrens (Thryothorus ludovicianus) are common birds who are beneficiaries of warming temperatures. They've steadily been spreading their range northwards and westwards now for decades. Their ranges quickly contract when hit by harsh weather. Ten subspecies are now recognized, 6 North of Mexico. Their scientific name translates from Greek and Latin into "reed jumper" "of Louisiana." Of the 9 wren species, Carolina's are the second largest in the USA, with males being slightly larger than females on average.
     These 5.5 inch birds are quite active. They have a white eye brow and tip their tails up, specially when alarmed. They're also quite vociferous, with the male giving a distinctive "Teakettle, Teakettle, Teakettle" song regardless of season. Both males and females also give alarm, scold and other calls year round, the pair often vocalizing together. Here's an example of a male giving its call:

                                   https://www.youtube.com/watch?v=O_lqToJZJwQ

     Here is another giving various scolding calls:

                                   https://www.youtube.com/watch?v=m7mDdO1ngrk

     Pairs often mate for life and defend their territories from other wrens and even other birds while nesting. Both sexes build the nest, though the female chooses the nest site and usually puts the finishing touches. Nest sites tend to be less than 10' high and are often slightly domed, but that's where the similarities end. They've been known to nest in all sorts of unusual places. While they may utilize cavities and bird boxes, they will also nest in all sorts of other locations. I've found them in flower pots (specially if they've been tipped sideways), mail boxes, and air vents. They've also been documented in brush piles, pails, coffee pots, baskets, roots, old hornet's nests, dense shrubbery, discarded cups, brush piles, pockets of clothes, and pails, among others.
     The female lays 4-8 creamy eggs on average and takes on the majority of the incubation. In 12-14 days, the eggs hatch. In about 2 weeks, the young fledge. The male often finishes raising the young while the female starts to nest again. Two to three broods a year are normal. They are common victims of brood parasitism by cowbirds, suffering 25% nest loss in some locations, though most of these are for the first nesting. Wrens often have better success in subsequent nesting attempts that same year.

A newly fledged wren.
     Wrens feed mostly on insects and invertebrates, 94% of their food consisting of these, particularly while nesting. In many locations, spiders make up a significant portion of their diet. With a bit of luck, they have been known to live over 7 years.
     Being year round residents and being so vocal, these are birds I enjoy in all seasons. They are not shy and make their presence known all year long. No wonder they have been chosen to be the state birds for South Carolina.


Thursday, February 9, 2017

Bird Friendly Homes

Silhouettes or decorations of almost any kind can help make birds aware of glass windows, specially if placed 4 or so inches from each other.

     Many people love birds and try to their best to help them out. This often takes the form of providing bird feeders, but there are much better ways. Planting native plants actually provides much better food (and cover) than setting out seeds. Since 97% of our terrestrial birds (and all our bats by the way) feed on insects, and native plants result in over 4 times the number of insects, this is truly best way to provide nourishment. Indeed, experiments done locally have shown that yards with nonnative plants cannot support as many birds even with bird feeders around. Baby birds have been found in yards landscaped with nonnative plants dying with crops full of seed, since what they really need is the protein and other nutrients insects and other invertebrates provide. Even birds such as hummingbirds and finches which are known to feed on nectar and seeds respectively need to have insects to feed their young. They cannot fledge successfully with out them.


Insects, specially caterpillars which feed on native plants, make up 97% of the food for terrestrial birds, particularly while young. Look at how many caterpillars this Common Grackle is taking back to feed its young.

     But there are many other ways to make your homes more bird friendly. Some are quite obvious such as keeping cats indoors for the protection of both the pet and birds. But another way to make your yard safer for birds is to try and keep birds from colliding with windows. 
    According to the American Bird Conservancy, bird collisions resulted in deaths estimated at between 300 million to 1 billion in 2013 in the USA alone, second only to cats as far as anthropogenic threats. While much has been written about birds crashing into tall buildings at night or from wind turbines, this isn't the most common manner of avian strikes. About half of all collisions are due to home windows, with the peak occurring during Fall migration and during the day. This is due to the large amount of glass found in houses that is present low to the ground where vegetation grows. Add bird feeders and unfamiliarity with the habitat while migrating and you have a recipe for window strikes. Something as simple as having window screening would go far in reducing fatalities due to less reflection and a buffering effect. 
     Bird friendly building design includes reducing exposure of glass, minimizing the amount of glass used, and including some kind of signal on or in the glass. These can have additional benefits such as energy use reduction, less glare, and added security or privacy. Actions as simple as installing window screen and closing shades or otherwise covering glass when not in use are extremely effective. The American Bird Conservancy provides numerous examples of bird friendly glass on their website. This included adding bird tape and hanging silhouettes or other things to the outside of the glass. The vast majority of strikes are also limited to the height of the vegetation. So even modifications or efforts to prevent crashes in tall buildings need not necessarily be undertaken on the upper floors or at great expense. They need only be as tall as the surrounding vegetation.
     Many people are familiar with the dark hawk silhouettes that have been used on windows to try and keep birds from colliding with them. Some believe this is due to birds being afraid of the hawk shape on the glass. In reality, that's not the reason these efforts reduce bird strikes. Any shape that helps make the surface standout works just as well. Many window decorations can therefore be used to reduce bird crashes. In some nature centers I've worked at, we would change the window decorations seasonally. Whether colored leaves in the fall or winter snow flake shapes attached to the outside of the glass were used, they all helped keep birds from accidentally smashing into the glass. The best results are when the shapes are placed 4 or so inches from each other.
     So go ahead and be more bird friendly. Plant native plants, keep cats indoors, and do what you can to make your windows safer. Whether you install window screens, close your shades, or attach some decorations to the outside glass, all can help reduce bird collisions. 
     

Tuesday, January 3, 2017

Monarch Way Stations


     The winter months can be ideal for planning our gardens, looking over catalogs, doing research into plants, and otherwise setting yourself up for success for the growing season (as well as providing some inspiration during dreary weather). One particular type of habitat garden that can be planned is one focusing on Monarch Butterflies, but which ends up benefiting many other pollinators and wildlife. Since my own Arlington County has committed itself to a National Wildlife Federation program called the Monarch Pledge, I thought I'd provide some details to help you support this pledge and otherwise provide information on setting up a particular type of Pollinator Patch. The Monarch Pledge is one taken by mayors and other local governmental leaders committing themselves to create habitat and educate citizens on how they make a difference at home. Frankly, this short article is an attempt to help do that. 


A Monarch Butterfly shares a meal of Swamp Milkweed nectar with a Hummingbird Clearwing Moth in the Certified Monarch Way Station at Gulf Branch Nature Center.

     More and more people are becoming aware of the plight of the monarch butterfly. While it has been introduced or spread into some new places it was not found before, there has been a large decline in its numbers in its historical range. This large orange, migratory butterfly may have gotten its name in honor of King William III of Orange and because it was said to rule over a vast domain. Now however it faces many threats including habitat destruction (both here and on its wintering grounds). What may be a weed to us is often an important food source for an animal. In this case, the sole food for monarch caterpillars (called the host plants) are plants in the milkweed family (Asclepias species for the most part). Since the caterpillars can feed on nothing else, this is one "weed" that needs to be conserved and indeed encouraged.


A Monarch Butterfly egg hidden under a milkweed leaf.

     Thus came about the notion of planting Monarch Way Stations. The idea was put forth by one of the leading monarch conservation organizations, Monarch Watch. By having individuals and communities plant both larval food sources (milkweeds) for the young and nectar sources for the adults, the loss of habitat could be offset and some conservation gains could be made. This plan is now getting a lot of support from schools, butterfly clubs, and many other organizations. So what do you need to make your own positive impact for monarchs? In addition to restricting pesticide use, why not plant a garden specifically for monarchs and get it certified as a Monarch Way Station? It is not as difficult as you might think as long as you keep certain principles in mind.     
     The first principle is to make sure you have a good location. Since butterflies are “cold blooded,” an area that receives 6 or more hours of sun is better than a shady area. This also helps since many of the blooms adult monarchs prefer are sun-loving. Next try and group your plants together and plan for flowers that will bloom throughout the season. It is easier for butterflies to see masses of blooms and a longer blooming period will of course provide more nectar food sources. For certification, at least 4 nectar sources are required, but the more the merrier. Native plants are the way to go, with some of the best being the goldenrods, joe-pyes, ironweeds, asters, composites, and coneflowers. Avoid cultivars such as double flowered varieties which may produce less nectar, and obviously don't use pesticides which may harm the caterpillars or other beneficial insects your garden may attract. 


Sweet smelling Honeyvine (Cynanchum laeve) is one of several vines that Monarchs will also use as host plants for their caterpillars. Going by various other names such as Sandvine or Climbing Milkweed, it may be a little too aggressive for formal gardens. 

     Most importantly, provide milkweeds (Asclepias species mostly) as host plants. For certification, at least 10 plants of 2 different species are required. Luckily for us, milkweeds are an adaptable group and there are probably some that will do very well despite your growing conditions. Virginia is blessed for instance with 13 native Asclepias species plus 4 climbing vines that Monarch caterpillars can feed on. Most are also deer resistant, at least once they get more mature. For the best results, cut the some of the stems back in late summer after they've bloomed. Fall is the when we get the most Monarchs laying eggs on our milkweeds. Since the mother butterflies prefer young, more tender growth, you can provide this by timing your pruning so there are new leaves by September or so for the arriving Monarchs. Just make sure to leave a few to produce pods for seeds. 


A Monarch caterpillar feeding on Common Milkweed.

     The local monarch favorite is Common Milkweed (A. syriaca), but this may not be the best for a formal setting since they spread by underground stolons and so will not "stay" where they are planted. They are certainly quite useful in less formal and school settings and are the favorite because they have the most toxic compounds (cardiac glycosides) the caterpillars need to make themselves distasteful to predators.     


The copious amounts of nectar that Common Milkweed produces attracts many pollinators such as this Perplexing Bumblebee, with a Pennsylvania Bumblebee in the background. While not suitable for every garden, Common Milkweed is favored by many insects besides Monarch caterpillars.

     A better option for most gardeners might be Swamp Milkweed (A. incarnata) which, despite its name, does fine in regular garden soil and doesn’t spread by runners. It will do well in clay also (as does the Common Milkweed). Most consider its blooms to be better looking as well. The same is even more true for Purple Milkweed (A. purpurascens) which will also handle wet conditions, but as long as they eventually drain well, and it does very well in sandy situations.


Purple Milkweed in bloom.


     If you have hot, dry conditions, then try Butterflyweed (A. tuberosa). Once established, it can take droughts and even some cutting. It is the least favored by monarch caterpillars though because it has very little toxin (cardiac glycosides) in its leaves, but other butterflies and adult monarchs love it as a nectar source. Why do you think it’s called butterflyweed? 

Butterflyweed Milkweed isn't just for butterflies...

     Other native species that might work for you include another species that does well in just ordinary soil, the Whorled or Horsetail Milkweed (A. verticellata) which tends to stay short. White or Redring Milkweed (A. variegata) is also supposed to be easy to grow, but much harder to find, and it can take wet areas. If you have dry, sandy soil, try Blunt-leaf or Sand Milkweed (A. amplexicaulis). There are also some species that will tolerate shadier conditions such as Green Milkweed (A. viridiflora)Poke Milkweed (A. exaltata), and Four-leaved Milkweed (A. quadrifolia). The last one is native just west of here. There are plenty of native alternatives for just about any garden site, as you can see, so it's best to stay away from some of the exotic milkweed species such as Balloonflower or Bloodflower which some people believe may have some negative drawbacks for our local Monarchs. 


Green Milkweed is among the more shade tolerant milkweeds. This is from the garden at Long Branch Nature Center.

     While Monarch Way Stations and their component plants are meant to help the Monarch, obviously many other animals benefit. Twelve different species of caterpillar have been found to also feed on milkweeds, though many are only native South of our region. More over, 457 different insect species were documented on a single milkweed patch during a one year study by Lewis and Clark Community College in Godfrey, Illinois. 


A Monarch caterpillar feeds on an immature milkweed pod along side immature milkweed bug nymphs. Many milkweed feeders have bright colors to advertise their distastefulness to predators from their use of toxins sequestered from the milkweeds.

     These insects and other arthropods then feed many other animals. While pollinators visiting the flowers are the most obvious of these, there are quite a few others. For example, 97% of our terrestrial birds feed on insects, specially caterpillars, and so will benefit from your garden. All 17 species of bats we have also eat insects, so they all benefit as well. Then of course comes the enjoyment we get from the garden we've provided. It's a win-win for everyone involved. 
     So go ahead and plant a Monarch Way Station, start planning it now. Find out more about how to set one up and get it certified from the folks at Monarch Watch: http://monarchwatch.org/waystations/  Then sit back and enjoy your way station, benefiting so much more than monarchs and yourself...


Great Spangled Fritillary Butterflies on Swamp Milkweed.