Sunday, June 30, 2013

A Word on the Recent Flooding and Then: Hairstreak Deception Display and the Eight-spot Forester

One of the preserve's brooks transformed into a raging torrent
The day I'm writing this, our region is experiencing a flood of historic proportions. A single storm dumped over 3 inches of rain on an area that was already super-saturated by previous heavy rains. Local flood damage is considerable and at the nature preserve, many of the trails and access roads have been damaged. So far our main beaver dam is still holding, but it is undergoing great stress from streams swollen beyond what they had ever been in living memory.
Many of the preserve's footbridges were washed away
A couple of years ago, a less extreme event was referred to as our one hundred year flood. So I guess this must be our 200 year flood!? I'm sure to devote a blog post to this significant event soon, but for now it's back to the regularly scheduled post:
Spring Azure Butterfly
Last month it looked as though we were starting to have a good butterfly season, but then a turn in the weather (toward the extremely wet side) would seem to have effectively suppressed their numbers. Fortunately the season is still young and there remains time for their numbers to bounce back. 2 butterfly species that emerged this week were the Eyed Brown and the Striped Hairstreak. At the preserve, the Eyed Brown is common in only one wet meadow where that butterfly’s main food plants sedges, grow plentifully. They are medium-sized butterflies and they are weak fliers –never flying very high over the vegetation and frequently stopping to perch.
Eastern Tiger Swallowtail
The Eyed Brown Butterfly only breeds in one wetland on the property
The Striped Hairstreak is one of 5 species of hairstreak that we have cataloged on the property. All of these species are small and easy to overlook. The Striped Hairstreak that I came upon today was feeding on nectar from Indian Hemp flowers, which have themselves only now just begun to bloom.
A Striped Hairstreak Butterfly on Indian Hemp flowers
A close up on the Hickory Hairstreak's false eye and antennae 
I'm not sure if it was on account of my presence or the presence of a bee on an adjacent flower, but the hairstreak was in full defense mode. With its wings kept closed over its back (a standard posture for a hairstreak butterfly) the insect was alternately lifting one hindwing and then the other, thus making  the hair-like projections at the base of its tail go up and down. It is surmised that the hairstreak does this in order to deceive would-be-predators into believing that the hair-like projections are the moving antennae of a more formidable insect.
Striped Hairstreak on Common Milkweed flowers
Mourning Cloak Butterflies are starting to show up just lately
The eye spots, which are also located at the base of the hairstreak’s hindwing, assist in creating the illusion that the creature’s tail is actually its head. Since predators (usually birds) most often target what they perceive to be a insect’s head – in the case of the hairstreak, instead of issuing a fatal blow, they end up with merely a mouth full of tail, and the hairstreak can usually slip away. With only a chunk missing from its hind-wing, the butterfly would be alive and quite probably still flight worthy.
The Eight-Spotted Forester Moth on a Ninebark Bush
2 foresters face-off on the same flower
The first Eight-spotted Forester Moths were found visiting our incredible Ninebark bushes. These day-flying moths are medium sized, black and have 4 large pale yellow spots on their forewings and 4 large white spots on their hindwings. They also have distinctive orange scaly projections on their legs. The caterpillars of this species are quite colorful - they are white and orange with many black bands and black spots. The larva feed on wild grape and Virginia Creeper - 2 plant species that we have plenty of.
The White Admiral is becoming more common in recent days
A pair of White Admirals spend some quality time on animal droppings
A picture destined not to be included in any butterfly calendar
White Admiral Butterflies are on the move just lately –though nothing remotely like influx of Red Admirals that we all experienced in the spring of 2012. I've been seeing White Admirals primarily following the roadways, which is an inherently dangerous behavior that results in many of them ending up as road-kill. Most of us think of beautiful butterflies nectaring on equally beautiful flowers, but in fact they will also readily drink from muddy puddles or even lick rocks on occasion. Not infrequently I'll discover them happily imbibing moisture (or presumably something of value) from animal droppings. It doesn't always make for the prettiest pictures, but it is interesting!

Sunday, June 23, 2013

Flickers and Other Cavity Nesting Birds at the Beaver Pond

The Yellow-shafted Flicker nests at the beaver pond nearly every year
There is no better place for flickers and other cavity nesting birds to look for homes than at a beaver pond.  As ponds are created and/or increase in size, stands of trees can become flooded out and die, thus leaving a great amount of potential bird housing.
A female Hairy Woodpecker feeds prepares to feed her nestlings over the pond
The House Wrens use a nest hole that was originally excavated by a downy woodpecker
The holes that Woodpeckers chisel out and use, may be reused several times by other bird species- including species that otherwise lack the ability to excavate cavities. Wood Duck, Great- created Flycatcher, Screech Owl and Bluebird all fit into that category. To a large degree these species and many other depend upon the presence of woodpeckers in their environment in order to reproduce.
A White-breasted Nuthatch looks for a suitable nest cavity at the beaver pond
Like the other woodpeckers, Yellow-bellied Sapsuckers can make their own nest holes
With such small bills, you wouldn't think that Black-capped Chickadees would be very good at digging out their own nest holes, but they often manage it. Sometimes they select a place where a woodpecker had only begun to chisel out an entrance way. If the wood is somewhat decayed and therefore sufficiently soft, the chickadee pair will work as a team to dig out a proper chamber. One at a time they come out with beak-fulls of saw dust, which they release into the air as they fly from the site. Such an operation can take several days.

Chickadees excavate their nest hole a beakful at a time
Nesting over the water gives added protection from land bound predators
Most of our resident woodpecker species will sometimes reuse old nests and a few of them, including the Flicker will accept man-made nest boxes. A few years ago I watched a male Red-bellied Woodpecker remove a Red Squirrels nest from a hole that was originally made by a woodpecker. The Red bellied Woodpecker would be the 3rd known owner of this apartment. Squirrels commonly make use of woodpecker holes and depend upon them as much as other non-excavating cavity nesting birds.
The Red-bellied Woodpecker removes bedding material left by a Red Squirrel family
The male Flicker excavtes a new nest hole in a dead American Elm tree
Of our woodpeckers, the Flicker is most likely to be seen on the ground foraging for ants
Currently at the beaver pond we have 5 species of cavity nesting birds in residence. The Flickers are now at the stage of feeding nestlings. Both parents take part in feeding, but as the young grow, the male's role will become more dominant as food provider – and he will be seen making more trips to the nest.

Mother Flicker has many insistent mouths to feed
Young Flickers fan out their wings - revealing their yellow shafted feathers
Woodpecker nestlings are remarkably boisterous, and their loud begging calls often make locating their nest trees a simple task.  The fact they are so loud is somewhat of a puzzle  Obviously, it encourages their parents to hurry up with the food deliveries, but one would think that it would also alert nest predators that there is a tree full of tasty woodpecker babies just waiting to be pilfered. Somehow though, woodpeckers seem to enjoy more breeding success than birds which use open nests - so having loud babies wouldn't seem to be causing an inordinate amount of harm.

The Pileated Woodpecker makes a nest hole big enough for Wood Ducks to use
The male Wood Duck goes house hunting in the Pileated Woodpecker's domain
Flickers as very young nestlings, produce a kind of buzzing sound upon approach. It is thought that this buzzing, which sounds like a swarm of bees, is meant to keep predators like Red Squirrels away from the nest. 
The male Eastern Bluebird often nests in woodpecker holes located at beaver ponds

Sunday, June 16, 2013

Distraction Displays by Ovenbirds & More

The Ovenbird - looks like a thrush, but belongs to the warbler clan
It's not unusual this time of year to come upon a particularly visible Ovenbird. Often enough this species can be difficult to observe; however, come the breeding season, Ovenbirds become very protective of their nests and young and will come out of hiding with the smallest provocation. All it takes is for someone to come too close to their unseen nests or to their fledged young and they will be scolded with volleys of sharp warning calls. Sometimes both parents will pace back and forth on an open branch, calling and nervously twitching side to side. That is of course interesting behavior, but it doesn't qualify as a distraction display.
An Ovenbird parents gives sharp "smack calls" to warn off potential predators
The Ovenbird's nest - said to resemble a Dutch  oven - built on the ground with a roof over it 
The female Ovenbird incubating eggs in her cave-like nest
The other day in the old woods I came upon a male Ovenbird that was definitely upset by my presence. He did some of the expected scolding, but mostly he engaged in a distraction display. He ran in a wide circle around me –evidently trying to draw me away from his unseen nest and/or young. Periodically as he ran he would relax his pace, spread his tail,  drop it to the ground and then take a few quick steps. Sometimes he would augment his performance by partially spreading his wing feathers and allowing them to droop. The aim of his display was to create the impression that he was injured and would therefore be an easy target for a predator or for an intruder that was otherwise bound to discover his nest.
The male briefly Ovenbird sings from the forest floor
The distraction displays begins with intermittent tail dragging
Note the spread tail feathers and slightly drooping wings
He fearlessly walks up close to me
A fledgling Ovenbird perched on a low branch in the forest understory
Though I've seen other birds perform similar distraction displays, I don’t recall having seen the Ovenbird's version. I'm much more familiar with the type put on by the Ruffed Grouse and the Killdeer. They most often feign mortal injuries - reel around on the ground or limp about pathetically. The mother grouse will also sometimes emit shrill alarm calls that make it sound like she’s in agony. However, given the opportunity, not every species that is known for giving distraction displays will perform one. I've had just as many grouse mothers simply fly off into the brush and allow their young chicks to rely on their own camouflage and their abilities to remain motionless until the danger passes.

Killdeer are famous for their flamboyant distraction displays
A mother Ruffed Grouse staggering around with tail spread and neck feathers "ruffed" out
Once I had a hen turkey engage in a kind of distraction display right in front of me. It consisted of her fearlessly running in circles around me, while clucking madly. I was definitely distracted by her, and I never did see any of the poults that she was protcting. One other time, I inadvertently startled a turkey hen whose reaction was to explosively take flight and abandon her clutch. The young poults, which were probably only a few days old, all instinctively played dead. 10 of them were strewn about the grassy trail –motionless and looking like victims of a bloodless massacre. Their cryptic plumage did much to hide them, but for sure, the effect would've worked better in taller grass. As I was leaving, they began to make high pitch distress calls and soon the hen returned to collect them.
A very young turkey "poult" tries to disappear in the weeds
They remained absolutely motionless until I moved well away
A couple of years ago I apparently got too close to the nest of a Hooded Warbler. The female Hooded performed a distraction display quite similar to that put on by the Ovenbird; she ran about in front of me, dragging her tail and trying her best to lure me away from her unseen nest. Again, this is another species that is not generally known for these kind of distraction displays and indeed in my many years of observing Hooded Warblers on their nesting grounds, this was the only one that ever behaved in that manner.
The male Hooded Warbler issuing alarm calls near his nest
The female Hooded alarm call watching over her recently fledged brood

Sunday, June 9, 2013

More Troubles for the Preserve's Beaver Colony

Julia swims in calm waters a few hours before the storm
Gentian and Tippy enjoy a playful shoving match on the day before the flood
On May 29th we had a tremendous downpour. In less than one hour, several inches of rain fell. The area’s streams - many of which had been barely flowing, were instantly transformed into raging torrents. Some streams at the nature preserve jumped their banks and one footbridge was washed away. All of the beaver ponds were immediately filled to capacity, but the major dams held. At May Pond where the beavers reside, the downstream side of the dam looked like Niagara Falls. The entire span had water gushing over it, but somehow that dam too was holding.  Despite how loud and intense the scene seemed to me, Julia, the adult female beaver, was quite casually floating in brown water of May Pond, munching on some poplar bark.
After the downpour, May Pond turned the color of chocolate milk
2 days after the storm the dam at May Pond did fail (talk about a delayed reaction) when a 15 foot span collapsed in the center of it. The breach caused a rush of water to head downstream and that in turn damaged the makeshift repair work that had been done on Secret Pond’s dam back during the winter.
May Pond as seen through the gap in the dam
Of course May Pond was much smaller that Sarah's Pond, which ruptured about a year ago and resulted in the loss of 4 beavers including May Apple, the colony's patriarch.  This event, as far as I could determine, was probably not lethal. At least Julia and the 3 one year-old beavers that constitute the known members of our colony were all accounted for following this dam break.
The normally underwater lodge enterance - now exposed
A major concern for beavers following an event of this kind is the state of the lodge. Unfortunately, the lodge at May Pond is now well above the water line and all of its entrances are exposed - which is not at all how beavers want it. Underwater entrances are what keep out the majority of predators as well as other animals that may be in the market for a den site of their own.
Julia makes her way up the stream channel that used to be May Pond
Just to put the frequency of major dam breaks in perspective: Those that read this blog may think they are very common, seeing as though we’ve now had 3 major breaks in one year, but in the previous 13 years at the nature preserve, we only had one.
Julia works to repair the dam at Secret Pond
Repair work on the dams at May Pond and at Secret Pond seemed to begin immediately after the breach. This time however, instead of experienced dam builders like May Apple, Blueberry or even Badger, the work was being taken on by the yearlings and by Julia. I’m afraid that this crew were not proving to be very proficient at the job. Julia is 6 years old, and obviously a very experienced beaver, but she's had little practice in dam building. In the past there had always been other beavers - mates or other family members to take care of that kind of work. But now here was Julia, in the early afternoon, working to rebuild the crude patch that was placed on Secret Pond's dam after it too was breached during the winter. She seemed to be working in earnest, but was easily drawn away from the task at hand by any number of distractions.
Gentian tries free a long branch in order to add it to the dam patch at May Pond
The yearlings - Gentian, Tippy Canoe and Tupilo were all working on putting a patch on the May Pond dam. It was proving to be an especially difficult task for them. They were cutting leafy honeysuckle branches, shoving them into place and plastering them with mud, but whenever they had a modest patch in place, the heavily flowing stream would carve a large gap below it - or would quickly erode the mud alongside it. It was clear that were getting nowhere and truthfully, their dedication to the job was less than awe inspiring.
The dam patch wasn't working very well and soon the yearlings gave up on it
Last year when Blueberry (now deceased) and Badger (now missing for 2 months) remade the dam at Secret Pond and simultaneously excavated a new lodge, they displayed the best of beaver engineering prowess and of perseverance. They worked round the clock until the job was completed. But they were older and more experienced animals. Given the situation as it stands, there is little chance that our current much reduced colony will have either Secret Pond or May Pond up to speed anytime soon.
A Gray Catbird hunts for stranded tadpoles and other tasty morsels in mud flats of May Pond
A Green Frog coming to terms with the fact that its pond habitat has disappeared
It seemed clear that the beavers’ only option was to abandon the site. Fortunately, we still had one pond in the beaver pond system that had an intact dam and a viable lodge with underwater entrances. Julia made her way up to the first pond, which is called Morton's Pond, and checked it over. That pond was first used by Julia's parents (Morton and Sarah) back in 1999. Julia had lived there herself as recently as the winter of 2011 - ‘12, but these yearlings had likely never seen it before.
Morton's Pond was the only good option and the beavers ultimately adopted it
Julia again happily munching Aspen leaves in Morton's Pond
After determining that Morton’s Pond was still viable and the dam (after some minor maintenance) would be able to support the small colony, Julia returned to May Pond to get the others. I happened to be at Morton's Pond when Julia and 2 of the yearlings came over the dam and entered the pond. They came in as a tight group – head to tail, like a beaver train. I've noticed that since this latest disaster they are engaging in a lot more family bonding than usual. They are being more solicitous with each other and also greeting each other with more enthusiasm.
Gentain and Julia feeding alongside each other
Dragging a branch back to the lodge at Morton's Pond
Tippy and Gentian feeding on Aspen leaves
So our beaver colony continues. With luck, during the course of the summer, the young beavers will continue to hone their work skills and come the next challenge they will be able to respond in a competent manner.
A House Wren nests in a dead snag over Morton's Pond
The male House Wren sings on top of the nest tree
Viceroy Butterflies mating next to the pond
Blue Flags bloom along the shore of one of the ponds