Monday, July 30, 2012

Too close to home

When we found the lost chick, we looked all over the garden for its nest, but without success.  However, when I went to the garage the next day, one of the Eastern Phoebe parents started making its "chip" call at me again.

* To see this video in high definition (1080p), you may need to (1) click "YouTube" to watch on the YouTube website and (2) change the settings at the bottom of the video screen.

The bird flitted among several trees in the proximity of the garage and continued to call.  I knew that I must be close -- too close for the comfort of the parent.  Turning back towards the garage and looking up, I finally found the nest. 

Eastern Phoebe (Sayornis phoebe) nest
An Eastern Phoebe (Sayornis phoebe) nest on top of a column.
It was quite a relief to see that there were surviving chicks!

What I hadn't known before is that Eastern Phoebes commonly build their nests on buildings.  This nest site -- on a column underneath a deck -- should have been one of the first places that we checked.  Nevertheless, it wouldn't have helped to have found the nest the night before.  The nest was too high to reach without a ladder, and any attempt to return the lost chick could have endangered the rest of the nestlings.

Friday, July 27, 2012

The lost chick

As much as I enjoy getting a chance to see a bird up close, I am anxious when I encounter a bird that isn't able to fly away from me.  Such was the case with this Eastern Phoebe (Sayornis phoebe) chick that my mother found sitting on the lawn.

An Eastern Phoebe (Sayornis phoebe) chick with a Japanese beetle (Popillia japonica) stuck in its beak.
The chick only turned its head slightly and blinked at me when I came near to take a picture.  Upon close inspection, I saw that it was holding a Japanese beetle (Popillia japonica) in its beak.  Meanwhile, the parent birds scolded us from nearby trees.  It seemed best to give the birds some space, so that the parents could approach and care for the chick.  After we moved away, the chick fluttered about the lawn and eventually disappeared from sight.

At first, we were pleased to see a native species reducing the number of destructive Japanese beetles in the garden.  However, when I found the chick again in the evening, I was unsettled to discover that the beetle was still in its beak.  Young birds need to eat frequently -- I was afraid this one might already be starving.  After getting tweezers from the house, I approached slowly, but the chick seemed too exhausted to move away.  Pulling gently on the beetle, I found that it was indeed stuck.  Its claws had become hooked into the chick's throat.  Working as carefully as I could, I managed to unhook the beetle.  I scooped the chick into an empty nest that we had in the house; then, with darkness falling rapidly, we secured the nest onto one of the branches we had seen the parents use as a perch.

We hoped to give the chick another chance, but, sadly, it did not survive the night.

Wednesday, July 25, 2012

A galling development

The rose bushes in our garden appear to be going through a difficult age.  Each time I walk by, I notice more large red "pimples" swelling up from their leaves.

Wasp galls on rose leaves.
To my surprise, when I poked one of these "pimples", it popped right off the leaf.  Curious to know what, if anything, was inside the gall, I dissected it.

Wasp larva inside a rose gall.
Inside, I found the culprit.  A wasp larva (probably Diplolepis sp.) was growing inside the gall, feeding on the soft tissue of the walls.

Monday, July 23, 2012

The curse of the mummy

This weekend, to explore a bit further afield, I visited a public garden.  While the other visitors were admiring the densely packed flower beds and jotting down the names of plants, I was inspecting the undersides of leaves.  Leaves might not seem to have much to offer when compared to the brilliant colors of flowers and the fast-paced action of the insects that visit them.  However, the plainness of leaves disguises a world of quiet intrigue.

Often, the view from above provides a sign of the action underneath.  Chewed leaf edges are a clue that there may still be a hungry caterpillar below.

A furry caterpillar munches on a leaf.
Meanwhile, folded leaves can shelter a nest.

A female Misumena vatia guards her nest.
Even the leaves that look normal from above may hide a surprising secret.  As the people around me were busy identifying new plants to add to their own gardens, I discovered a mummy. 
A mummified caterpillar.
This caterpillar had been mummified by a parasite (likely a wasp).  The developing parasite would have fed on the caterpillar from inside before breaking out of the mummy through the hole that is visible at the top.

Friday, July 20, 2012

The cautious suitor

For a male crab spider, wooing a female can be a risky undertaking with potentially lethal consequences.  Therefore, it is understandable that the male Misumena vatia in this video takes its time and keeps its distance from the much larger female.  But will the male finally commit itself, or will it get eight "cold feet"?

Thursday, July 19, 2012

Two bird nests in the bushes

When I was growing up, my grandfather would carry me on his shoulders to let me peek into the bird nests he had discovered.  It was always such a thrill to see the delicate eggs in those nests tucked deep between the tree branches.  As the summer progressed, the eggs would hatch and it would become possible to locate the nests by sound.  Though tiny, the chicks would call loudly for food, their beaks opening incredibly wide.

Although now I generally search the garden for insects and spiders, today I was told that I might find one or more bird nests if I looked carefully.  One bird had been acting suspiciously, darting out of a thick bush and running along the ground whenever my mother approached.  Arming myself with my camera, I slowly studied the bush.

Can you see what is hidden near the bottom left corner of this picture?
Suddenly, from between the green branches, I got a glimpse of a nest with four eggs cradled inside.  Luckily, the bird was nowhere in sight and I was able to take a closer look without causing a disturbance.

A bird nest with four speckled eggs.
The adventure then continued at the rose bush.  Once again, I peered at the bush from various angles before finding the one that revealed another small nest...

This nest is not quite as well hidden.
... and two more eggs! 

There were only two eggs in this nest. Maybe there will be another egg tomorrow?

Tuesday, July 17, 2012

Paying for protection

Generally, when I inspect a plant in the garden, I do not want to find aphids on it.  Aphids puncture the cells that transport nutrients up and down a plant's stem and then drink the sugar-rich sap that leaks out.  Since aphids reproduce rapidly, they can inflict serious damage to the host plant if left uncontrolled.  Therefore, I almost always remove the aphids as soon as I can.

However, I make an exception when the aphids are accompanied by ants.  The opportunity to observe the ants trumps (at least temporarily) my concern for the plant's welfare.  Instead of just eating the aphids, some ant species will tend the aphids like livestock.  When the ants touch the aphids with their antennae, the aphids excrete a sugary honeydew that is collected by the ants.  The ants aggressively defend this valuable resource, thereby protecting the aphids from attacks by their natural enemies -- or, in the case of this video, a  dry grass stem. 

* To see this video in high definition (1080p), you may need to (1) click "YouTube" to watch on the YouTube website and (2) change the settings at the bottom of the video screen.

Saturday, July 14, 2012

Beetle mania

Despite their appealing colors and smells, ornamental roses do not reward flower visitors with much nectar.  This is not a problem for the invasive Japanese beetle (Popillia japonica), which will voraciously consume the flower itself.  The presence of a beetle on a flower quickly attracts more beetles, leading to a feeding frenzy.

Japanese beetles (Popillia japonica) on a rose flower.
In addition to devouring flower petals, the beetles will skeletonize leaves by eating all the tissue between the veins.  The beetles will feed on a wide variety of plants, and since they do not have many natural enemies in North America, they can number in the thousands within a small area and do devastating damage.

Wednesday, July 11, 2012

Keeping a safe distance

Some of the leafcutter bees in the last post were able to avoid being attacked by the crab spider by inspecting it from a distance.  But what distance is a safe distance?  The fly in the video below hovers in front of the daffodils instead of immediately landing.  However, even in mid-air, the fly is not completely safe from spiders.

Impressively, the spider launches itself into the air, aiming for the fly.  Although it misses and the fly escapes, the video demonstrates that just inspecting a flower may be a dangerous task.

Monday, July 9, 2012

Living to forage at another flower

The honey bee featured in the last post stumbled into a crab spider's ambush as it rushed from flower to flower.  However, some bees are more sensitive to the risk of choosing the wrong flower to visit.  Pausing momentarily to inspect a flower for danger decreases a bee's foraging efficiency, but it can be worth the cost if it extends the lifespan of a forager.

The bees in this video are European wool carder bees (Anthidium manicatum).  Although the first bee does not see the crab spider before it lands at the flower, it does manage to evade the attack and then returns to inspect the spider.  The subsequent bees observe the spider (which does not appear to be very well camouflaged), hovering briefly in front of it before flying off to forage at a less dangerous spot.  Unlike honey bees, these bees do not live in colonies.  Therefore, the cost of being killed while foraging is higher (the bee loses all future opportunities to reproduce or gather provisions for its offspring), making the benefit of vigilance higher as well.

Friday, July 6, 2012

All work and no vigilance makes a forager a dead bee

Honey bees are renowned for their hard work.  Outside the hive, foragers buzz rapidly from flower to flower, collecting nectar in a special stomach and pollen on their hind legs.  Inside the hive, there is constant motion as returning foragers communicate the locations of bountiful flower patches through 'waggle dances' and thousands of workers construct wax cells, process nectar into honey, store honey and pollen in the comb, and care for larvae.

Workers start out their adult lives with tasks inside the hive.  After a couple of weeks, workers may begin to leave the safety of the hive to forage.  While their single-minded dedication to work is often commended, their frequent neglect of danger as they carry out their tasks demonstrates the downside of being 'busy as a bee'.

The loss of a single forager is not very costly for a large honey bee colony and most foragers eventually expire out in the field.  However, as I'll show in a follow-up post, some other bee species are much more careful about what flowers they approach.

Wednesday, July 4, 2012

It's a spider eat spider world

Sometimes I find that I am not alone in my search for female crab spiders.  Male crab spiders are also roaming from flower to flower to find the ones where females sit in ambush.  In fact, twice --that I noticed-- male Misumena vatia climbed up onto me, as if they also recognized our common goal.  (To put it mildly, I do not appreciate this behavior; nevertheless, I did manage to remove the spiders gently in both cases.)

Like females, male crab spiders will hunt on flowers (see this post).  However, when seeking out a mate, male crab spiders may no longer be a threat to other flower visitors.  The male Misumena vatia in the pictures below stepped right over a foraging bee and continued on its way.

A male Misumena vatia walks right over a small bee.
In contrast, female crab spiders are unlikely to pass up a chance for a meal -- even if that meal is the male who just came to mate.

A female Mecaphesa sp. eats what looks like a male Mecaphesa sp.

Monday, July 2, 2012

Going to great lengths for a drink of nectar

The characteristics of a flower often provide clues about its pollinators.  Certain flower sizes, shapes, colors, scents and rewards are grouped into "pollination syndromes" associated with specific groups of pollinators. For example, bees often prefer to visit blue and yellow flowers with an open structure that allows easy access to nectar and pollen.

A honey bee (Apis mellifera) drinks nectar from an open flower.
In comparison, red flowers with a long, tubular structure are commonly associated with hummingbird pollination.  These flowers have nectar deep inside that hummingbirds can reach with their long bills and tongues.  For illustration, I have dissected a trumpet honeysuckle (Lonicera sempervirens) flower.

Some nectar is visible near the base, at least 3/4 of the way down the tube of the flower.
However, bees are not discouraged just because a flower belongs to the "wrong" pollination syndrome.  Both honey bees and bumble bees can squeeze their way into trumpet honeysuckle flowers, sometimes disappearing nearly entirely from view in their efforts to reach the nectar. 

A honey bee (Apis mellifera) attempts to reach the nectar at the base of a trumpet honeysuckle (Lonicera sempervirens) flower.
A bumble bee (Bombus sp.) forces its way up the tube of a trumpet honeysuckle (Lonicera sempervirens) flower.