July 26, 2012 | Volume 42, No.30

Wild Things

The worst of their hatch has passed, but have you ever wondered what good are mosquitoes? They do fit into the food webs. Many fish, birds, bats, insects, reptiles and spiders depend on them. 

In one study, purple martins produced fewer young in mosquito-free areas. Male mosquitoes eat nectar exclusively, while females need nectar and blood for laying eggs. 

Mosquitoes pollinate aquatic plants and members of the orchid family. Whether they pollinate blueberries and other berries is in dispute. In southern states, several species of bees pollinate berries, but as you move farther north, mosquitoes seem to assume a greater role in berry pollination. 

Also in the North, mosquitoes don’t harbor diseases like malaria and dengue fever. It just isn’t warm enough for those disease organisms to survive here.

Speaking of unwanted species, Haines has the distinction of having more invasive plant species than any other Alaskan town. Most people are familiar with Canada thistle or orange hawkweed, but there are several others.

Just what is meant by “invasive,” anyway? An invasive plant is a non-native plant introduced by human beings that can go beyond a human footprint and cause harm to native plant communities. Invasives do not bring their natural controls – like predators and disease – with them, so are unchecked like native plants. 

Most plants introduced by humans cannot leave the human footprint and invade native plant communities. Take broccoli, or peonies, or your lawn grass as examples. Some non-natives are introduced accidentally by humans on the tires of cars, the soles of shoes, or in animal feed. If they don’t leave the human footprint and cause harm, they are not invasive. An example is pineapple weed, or false chamomile, that stays in your driveway.  

The U.S. Department of Agriculture and U.S. Forest Service have rated plants according to their aggressiveness on a scale of 1 to 100. Anything over 60 is invasive. 

Dandelions are rated at 58. They are aggressive, but tend to stick to the human footprint such as lawns, roadsides. 

Ornamental jewelweed, on the other hand is rated at 82. It has rapidly invaded the beach wetlands on Portage Cove in recent years, crowding out the native plants. Our five most unwanted are reed canary grass (83), ornamental jewelweed (82), white sweet clover (81), orange hawkweed (79), and Canada thistle (76).

Invasives can clog salmon-rearing streams, killing juvenile fish, and crowd out native plants that are food for the valley’s wild animals. They also can change soil chemistry, inhibiting the growth of native plants.

Invasives typically produce prodigous numbers of seeds, can propagate by roots and crowd out other by “stealing” sunshine, water or soil nutrients, and be difficult to eradicate.

If you are watching eagle nests, you may start to see newborns now. They are getting large and strong enough to stand and be seen over the rims of nests. Male and female parents now leave the nest more often and for longer times, as junior can better protect himself. Eagles hatch at about three ounces, and by the end of August will weigh about 12 pounds. Fortunately, pink salmon are starting to come in, so ample food will be available for their voracious appetites.

If you have questions or observations, please call Pam Randles at the Takshanuk Watershed Council, 766-3542, or visit our website, www.takshanuk.org and add your observations and photos.