Addressing the Myth Concerning Deer and Ticks
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I often hear from the public that ticks are present because of deer.  That would suggest that high deer numbers would lead to high tick numbers and high levels of tick related diseases (http://www.skinnymoose.com/professorsblog/2013/08/21/comments-and-responses-regarding-ticks-being-proactive-for-your-own-health/) in humans.  So, if deer numbers are reduced the number of ticks will also be reduced.  However, the initial statement and subsequent logic is incorrect.  Let me start by explaining the life cycle of the blacklegged tick (Ixodes scapularis).  The black-legged tick undergoes two metamorphic stages (larvae and nymph).  At each stage a blood meal is required.  Also, as an adult the tick needs blood for reproduction.  However, over 100 vertebrates in North America can serve as hosts for the black-legged tick. 

Let us start as an adult.  An adult tick spends the winter in a dormant phase with a full belly of blood.  In the spring, she lays her eggs which hatch into larvae by mid-summer.  Larvae ticks patiently wait (called questing) for a vertebrate host to pass by and then attach and consume the first blood meal.  Because of their small size larvae ticks have been shown to primarily quest near the ground.  Hence, in the summer, the larvae attach primarily to shrews and mice.  The life cycle from egg to adult takes two years to complete.  The following fall, adult ticks will attach to larger vertebrates including deer for another blood meal and to mate.

Once the adult tick consumes blood from the deer and mates, they drop off.  Over a 4 week period, one deer can supply blood for over 2 million fertilized tick eggs.  Researches have concluded that all you need is a few deer to support high tick numbers.  More important to the presence of an abundant tick population is an abundant small mammal (shrews and mice) population which provides the initial blood meal for the larvae.  Also, mice, shrews, and chipmunks are inefficient groomers which allows many larvae ticks to survive.  Researchers have demonstrated that over 90% of nymphal ticks get their initial blood meal from mice, shrews, and chipmunks.

 

Photo obtained from the manuscript – A New View on Lyme Disease: Rodents Hold the Key to Annual Risk. Gross L, PLoS Biology Vol. 4/6/2006, e182. doi:10.1371/journal.pbio.0040182. Use of the photo does not represent endorsement of the article content.

However, the situation is more complex.  The infective agent of Lyme Disease, Borrelia burgdorferi, does not pass vertically (from mother to young) between blacklegged ticks.  Of the 2 million baby ticks that will hatch, none will be infected – they will be ‘clean’.  The larval ticks must pick up the B. burgdorferi spirochete from – you guessed it, a shrew, mouse, or chipmunk.  So, mammals actually make ticks sick which then make mammals (us) sick.  This phenomenon is called ‘reciprocal infectivity’ and is the reason that B. burgdorferi prevelance is high in tick and host populations.

Although deer are involved in the tick life cycle and transmission of some tick borne illnesses, they play a very small role.  In fact, researchers believe that deer and humans are dead end hosts – once infected the infection goes nowhere.  The infection does not go back into ticks.  Infected ticks bite mice, shrews, and chipmunks, which make the ticks carriers, the ticks then bite us and make us sick, and we don’t make anyone sick.

So, don’t blame the deer, blame the small mammals.

Further support can be found at http://www.thewildlifenews.com/2014/05/11/lyme-disease-rages-in-northeast/ where the authors discuss promoting meso-carnivores that prey on rodents and suggest that removal of white-tailed deer is an ineffective way to reduce tick numbers.

 

 

The impacts of feral cats on sea otters
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Recently, I came across a manuscript (http://www.otterproject.org/wp-content/uploads/2012/05/Conrad_etal_2005_Transmission_of_toxoplasma_clues_from_the_study_of_sea_otters.pdf) and a news link (http://news.bbc.co.uk/2/hi/science/nature/4729810.stm) concerning sea otters suffering lethal infections from a parasite,Toxoplasma gondii.

Previously, I have written about Toxoplasma gondii infections in feral pigs (http://www.skinnymoose.com/professorsblog/2013/05/26/toxoplasmosis-trichinosis-feral-pigs-and-hunters/) where my research tied the infections to feral cats.  Toxoplasma gondii is a protozoan parasite that infects domestic animals, wildlife, and humans (once transmitted is called Toxoplasmosis) through the uptake of oocytes, the infective stage. The oocysts are shed into the environment by a definitive host–cats. If oocysts are ingested by a non-cat host, including humans and sea otters, the parasite will invade and encyst in muscle tissue and organs, causing flu-like symptoms in humans with the possibility of more serious complications in those with weakened immune systems.  Further, transmission of T. gondii may occur by consumption of parasites encysted in muscle tissue, including improperly cooked meat or shellfish.

Two sea otters. Photo credit: Dave Bezaire &Susi Havens-Bezaire (the use of this photo does not indicate any endorsement of content).

It is likely that sea otters become infected by consuming infected shellfish (mussels, oysters, and clams).    Remember, many humans enjoy consuming shellfish!

It is believed that two routes of infection exist – 1) feral cats (or any outdoor cat) deposit their infected feces on land.  Rain then washes the feces into waterways (streams, rivers) and ultimately into the ocean.  2) humans flush infected kitty litter down the toilets and sewage treatment facilities may not kill the Toxoplasma gondii eggs (http://seaotterresearch.org/resources.shtml).  Following these potential routes of infection, shellfish (the primary food source for sea otters) filter the water and likely accumulate the parasite which is then consumed by sea otters and possibly people.

So, think about this – In 2012, the American Veterinary Medical Association and the Human Society estimated there was between 74 million and 96 million cats in the US, respectively.  Additionally, the number is expected to double in the next 10 years.

On this blog, you have read about feral cats being the definitive host for Toxoplasma gondii that is likely causing infection in two wildlife species – feral pigs and sea otters.  I am certain that as researches continue to study Toxoplasa gondii we will learn about more species being infected.  If you have cats, please keep them indoors and depose of the feces properly (http://www.skinnymoose.com/professorsblog/2013/10/28/the-impacts-of-feral-cats-on-wildlife/).

How wolves change rivers
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When wolves were reintroduced to Yellowstone National Park after being absent nearly 70 years, a remarkable “trophic cascade”  occurred.  What is a trophic cascade and how exactly do wolves change rivers?  George Monbiot explains in this movie remix.

 

 

 

 

 

 

 

Here are 2 links –

http://www.youtube.com/watch?v=NGhOzGbpEmI

http://www.liveleak.com/view?i=91e_1392504581

Eastern North Carolina Tundra Swans
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The tundra swan (Cygnus columbianus) is the smallest and most widely distributed swan species in America. Tundra swans have a wingspan of 5.5’ – 6.0’ and an individual may weigh between 8 -24 pounds. Tundra swans are often confused with trumpeter (Cygnus buccinator) or the non-native mute (Cygnus olor) swans. However, if you study the figure below identification is relatively easy.

Tundra swans can live up to 20 years in the wild. They breed in the Arctic and migrate nearly 4000 miles to the Pacific and Atlantic Coasts in the winter. Every winter, it is estimated that over 100,000 tundra swans migrate to the East Coast. Of those, ~75,000 winter in North Carolina with the remaining 25,000 wintering in Pennsylvania, Maryland, Delaware, Virginia, and New Jersey. The Western population numbers ~70,000 and occupies numerous western states including California, Nevada, and Utah.

During the winter in North Carolina, tundra swans gather in huge flocks. They sleep on the water at night but move to agricultural land to feed during the day. In the water, tundra swans will ‘tip-up’ and feed underwater on plants, tubers, roots, and shellfish. On land, tundra swans feed on waste grain including corn and soybean. It is believed that tundra swans mate for life. Individuals will form pairs for an entire year before breeding. Tundra swans breed as solitary pairs in the Artic (on their summer grounds).

Harvest management of tundra swans is guided by the Eastern Population Tundra Swan Management Plan developed and approved by all 4 flyway councils which are formal organizations that provide for collaboration among public wildlife agencies for the purpose of migratory bird conservation. Since the mid-1950s, the North American tundra swan populations has trended upward and appears to be stable over the last 10-15 years. The birds are managed and hunted for sport in some states.

In North Carolina, hunting for tundra swans began 1984 and today follows strict guidelines with only 5000 permits issued annually. Eastern Population Tundra Swan Management Plan recommends the sport harvest rate be below 5% (i.e., the percentage of the population that is harvested). Currently, the sport harvest rate has been ~4% and the Eastern Population Tundra Swan Management Plan allows 9,600 permits to be issued among the 5 states (Montana, North Dakota, South Dakota, Virginia, and North Carolina) that hunt tundra swans. Because of the large wintering flock and permit allocation, North Carolina hunters harvest more tundra swans than any other state. Virginia is the only other state along the eastern seaboard to hold a limited hunting season. Montana, North Dakota, and South Dakota have limited hunting seasons while swans are passing through on their fall migration.

In mid-January, my son (Christopher), daughter (Alexandra), and I went tundra swan hunting in eastern North Carolina. Christopher and I each drew our tundra swan tags and Alexandra was an observer. Although both kids have accompanied me on previous swan hunts, it would be Christopher’s first opportunity to shoot one of the majestic birds. We were joined by three good friends (Mike, Tyler, and Candice).

A little before seven am we arrived at the box blind and set the decoy spread anticipating how the birds would circle and land into the wind. With the ambush set, we settled in to wait for the birds to come off the lake. We saw the first flock just after 7 am but they were high and not close enough to respond to the call and they continued their straight path past us. Around 8 am a small flock of 6 birds approached the decoy spread, flew past, and circled back to the decoys.

The swans cupped their wings and stretched out their large, black feet. Two birds landed in the spread and the remaining 4 birds, for some unknown reason halted their descent, and flew past. One of the birds on the ground was nervous, ran, and quickly took flight away. The other bird began to follow and was 8-10’ off the ground when Christopher fired the 12 gauge with 3.5” #2’s and his first tundra swan went down. Over the next hour, we saw numerous small flocks and we were able to fill the remaining 4 swan tags.

Myself, Alexandra, and Christopher

The scenery in eastern North Carolina was beautiful and it was a great way to spend a Saturday morning. The time with friends was memorable and two hunters (Candice and Christopher) harvested their first swan. If you have never swan hunted in eastern North Carolina, you should definitely put it on your bucket list! If interested in applying and for season dates, please visit the North Carolina Wildlife Resources webpage for more information (http://www.ncwildlife.org/Licensing/PermitHuntingOpportunities/TundraSwan.aspx)

The impacts of feral cats on wildlife
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Recently, I received a few interesting emails with information on outdoor cats that I would like to share and comment on.  When referring to outdoor cats, I generally avoid terms like ‘stray cats’, ‘pet cats’, and ‘outdoor cats’ and although I cannot speak for all scientists, most categorize any cat that is outdoors as ‘feral’.  Why would we consider outdoor cats feral? Because cats are not native to the United States.  Middle Eastern countries such as Egypt, Turkey, Lebanon, and Iran are considered the primary locations of cat domestication.  From the Middle East cats spread through Asia and Europe then, with the Pilgrims, to North America.  Simply put there are no domesticated cats that are indigenous to America.

Recent evidence indicates that domesticated cats are now found throughout the world and are considered the most common and popular pet on earth. So, why should we care if people have cats as pets?  The answer – we should not as long as cats stay indoors!  Cats are efficient hunters and remember, cats are non-native to the US and it is believed that our native bird, mammal, amphibian, and reptile species are not adapted to cats.

A feral cat carrying a pigeon (Photo Credit: Yug. This image is part of the public domain.)

Researchers from the University of Georgia (http://www.kittycams.uga.edu/), placed video cameras on 55 house cats.  They noted that 44% of the cats hunted wildlife and they captured an average of 2 prey items during seven days of roaming.  Additionally, 85% of the cats engaged in high risk behaviors including crossing roads, encountering strange cats, eating and drinking questionable items, and entering storm drains and crawlspaces.  I encourage you to visit the above website and watch a video presentation of their research projects.  Also, I received the following comic that illustrates the magnitude of feral cats’ impact on wildlife (http://theoatmeal.com/comics/cats_actually_kill).  Essentially, the past estimates that feral cats kill ~1 million species per year is extremely low.  Now, it is believed the estimates of wildlife killed per year by feral cats are estimated closer to 3 billion, an astonishing number that has to have a profound effect on the ecological community.

In conclusion, although not a cat person myself, I appreciate the companionship that pets provide. Research showing the positive effects that pets can have on an individual’s health, happiness and emotional wellbeing are plentiful.  I am supportive of people having cats as pets as long as they remain indoors.