Download 1 - U of L Class Index

Cam’s Top 10
Biodiversity highlights from Field Biology, Aug. 21-27, 2011
1. Zombie ants
The behaviour of Dicrocoelium-infected ants is surely a
biological marvel. We observed ‘clinging’ ants on clover,
American vetch and goldenrod at various sites in CHP. The
‘clingers’ are common in CHP, but probably nowhere else in
North America. This pathogen of domestic grazers and
wildlife is an invader from Europe, infecting high
proportions of deer, elk, and cattle in CHP. Recall that the
first intermediate host is the terrestrial snail, Oreohelix,
common within aspen-dominated forests in CHP. In it’s snail
host, which is permanently castrated by infection, asexuallyproduced cercariae are housed within host-derived slime
balls. The slime balls, containing about 100 cercariae, are
favored prey of formica ants. Details are in Goater and
Colwell (2007).
2. Forest of death
We observed countless numbers of dead
yellow dung flies attached to certain types
of understory vegetation throughout CHP.
These flies are infected with the fungus,
Entomophthora muscae. The fungus
produces hyphae from the legs of flies,
which attaches them to plants. This is an
‘enslaver parasite’ that manipulates it’s
host’s orientation on the plant (see arrow)
to increase the rate of transmission of
spores to new hosts. On hot days, male
flies prefer to feed on nectar from shaded
flowering plants. This is the likely mechanism behind our observation that dead flies were
observed only on understory plants (such as bull thistle) near Camp McCoy. Details are in
Maitland (1994).
1
3. Harvestman Hay-day
We observed high densities of Harvestmen
throughout CHP, especially in the pitfall traps on the
grazing plots. We often find small numbers of
Harvestmen in the traps (from 0-5), but this year
there were often 100’s. There are 8 species of
Harvestmen in Aberta; we likely had Phalangium
opilio, an introduced species from Europe. This is a
classically ‘eruptive’ group of arthropods, whereby
certain environmental conditions lead to enormous
increases in population size. Their voracious apetites,
especially of noctural males, makes them suitable as biocontrol agents of agricultural pests.
Demographic characteristics of harvestmen have not been studied in Alberta (nor have their
mites!). Details are in Allard and Yeargan (2005) and Newton and Yeargan (2002).
4. Cougar
Perhaps fortunately, we did not see cougars. But we
did observe the cougar kill site near Camp McCoy, and
the fresh tracks along Beaver creek were unmistakable.
An ongoing study based out of U of A estimates that
there are 8-12 resident adults in CHP, with about 33
animals in total. Data from one radio-collared male
and a female show that over 90% of their diet over two
years consisted of elk, deer, and moose. CHP is an
important location for the re-establishment of this key
predator, representing the most eastern confirmed
location for breeding cougars in Canada. Details are in
Bacon and Boyce (2009).
5. Banded horntail
This large, distinctive insect (Urocerus gigas), known
as the giant wood wasp, was found in one of Dara and
Brayden’s pitfall traps within the recently logged pine
and spruce forests. This primitive sawfly can make you
jump, but the ‘stinger’ is actually the female’s
ovipositer that she uses to penetrate recently dead
spruce and pine trees to deposit eggs. Larvae bore
tunnels as they feed. This is a cosmopolitan species
that is often found in recently logged or burned
habitats. Check the video footage of an ovipositing female at
http://www.youtube.com/watch?v=MCSQ9zI-3lc.
2
6. Bedstraw hawkmoth and parasitoid fly
We found two of these large hawkmoth (Hyles gallii) catipillars on the upper plateau. Recall that
the larvae in the right-most petri dish once looked like the one on the left, until it exploded to
release about 12 larvae of a tachinid fly parasitoid. This hawkmoth is cosmopolitan within boreal
forests, found wherever it’s main food source, northern bedstraw and fireweed, is common. The
identity of the parasitoid is unknown.
7. Blackspot in minnows
Virtually all of the 1000’s of fathead minnows (Pimephales
promelas) in the small pond adjacent to Reesor Lake were
infected with the encysting stage of this fluke. This minnow
has two distinctive larvae just behind the eyes. The first host is
the pond snail, Helisoma, the second are minnows. The final
hosts are pelicans. Studies have shown that the black cyst
increases the conspicuousness of infected fish, leading to
higher predation rates by avian final hosts. Oddly, fatheads in
adjacent Reesor lake were very lightly infected. Details are in Tobler and Schlupp (2008).
8. American Redstart
This was one of several passerine birds that arrived in the array of mist
nets during the week. Recall that the sophisticated banding operation
that has been running for the past two years is producing fantastic
results from a conservation perspective. Most importantly, CHP is now
regarded as a critical staging region for an astonishing number and
diversity of birds that breed within Canada’s boreal and arctic habitats.
This redstart, Setaphaga ruticilla, one of the wood warblers, is a
classical boreal and aspen parkland breeder. It is well known for its
acrobatic fly-catching behaviour and its distinctive flash patterns in
flight. This individual had been caught and banded 6 days earlier. Over
that interval, it had increased its mass by about 20%, an adaptation
linked to its requirement to migrate 1000’s of kilometers to its
wintering sites in the tropics. See Bonter et al. (2006) for important
ideas regarding migration behaviour, stopover locations, and remote sensing.
3
9. Long-eared owls
This is a medium-sized, woodland owl. It is known to occur in CHP, but
it is very rarely sighted. Students that were lucky enough to visit the
roosting site with Jeremiah will recall a low, silent flier. They feed mostly
on voles and mice, but will also take birds and even amphibians. These
owls tend to use abandoned crow and magpie nests for nesting and
roosting. Nests are almost always found in heavily wooded edges adjacent
to clearings or grassland – exactly the type of habitat where we observed
this owl.
10. Parasitoid of Oreohelix
This is the largest and most distinctive of the approximate 12 species of terrestrial snails in CHP.
It is one of only a few viviparous snails in Alberta. This is a
favored prey of some birds and also mice. It is the first
intermediate host of Dicrocoelium in CHP. While Becky and
Steven were evaluating crushed Oreohelix for the presence of
Dicrocoelium, they found a small number of snails infected with
the larvae or pupae of an enormous parasitoid fly. We observed
several parasitoid/host interactions over the week (recall the
complex system involving the Solidago ball gall). But a
parasitoid fly of snails is a bizarre twist indeed. Details are nowhere to be found!
4