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April 11 - 20


Racine has 13 hours and 37 minutes of daylight and Superior has 13 hours and 52 minutes at the end of the period. Southern Wisconsin has an increase of 27 minutes and northern Wisconsin has an increase of 31 minutes of daylight over the previous period.




























White sucker: Common white suckers are one of Wisconsin’s most abundant freshwater fish species. Extremely adaptable, they can be found in almost any type of water. Larger individuals prefer lakes, ponds, or deeper sections of rivers and streams. In spring, white suckers migrate into swift flowing streams with gravel bottoms to spawn. Migration usually begins when water temperatures reach 50°F. They will return to the same spawning riffle year after year. In my home town, Waunakee, it’s a mid April tradition watch the sucker the run and spawning activities in the local parks and from foot bridges.


Isabella Tiger moth: This month is one of the best-known species in the state, although, most nature observers would not recognize the adult. This is one of only a few species much more recognizable as a caterpillar than the adult moth. The caterpillar of the Isabella moth is the famous wooly bear.


The adult is a relatively large moth up to 3 inches in size. It is a fairly nondescript with orange yellow wings and faint brown lines. The caterpillar is a very familiar with black fronts, orange in the middle and black rears, although blonde, brown, rust and tan forms occur. The caterpillars feed on many plants including dandelion and grass. The Isabella Tiger moth overwinters as nearly full grown woolly bears. They emerge in early spring, briefly forage, pupate and metamorphose as adults April. A second brood emerges in August.


According to folklore, they can predict the harshness of winters. The narrower the orange band equates to a cold winter. As the caterpillar grows, each instar replaces some of the black setae with orange. The older the caterpillar the larger is the area of orange. Thus, the width of the orange is a fairly accurate measure to confirm the quality of the previous year’s growing season.


Dragonfly migration commences: A few species of Wisconsin’s dragonfly migrate, either en masse or individually. Dragonflies follow weather fronts, fleeing cold weather on their way south in fall or chasing warm fronts in the spring when moving north. The best-known migrant is the common green darner, who makes a one-way trip so in fall and whose offspring make the return one-way trip north the following spring. Another seasonal migratory species is the variegated meadowhawk, may be seen in early spring returning from year round haunts farther south.


Blue-spotted salamander: In early spring, the blue-spotted salamander migrates to mating ponds. Males arrived first. Vernal ponds make good breeding grounds. These vernal pools are temporary ponds that fill with spring snow melt water and it’s just what the salamander needs.  The pools must hold water until late summer to allow enough time for the larvae to transform into adults. In spring, the male will hold the female with its front legs and rubbed his chin on her head. He then deposits a spermatophore (a packet of sperm) on the pond bottom. Next he positions her over the sperm. She will take the sperm in and fertilize her eggs.


Rainbow smelt: Smelt, also known as rainbow smelt spawn in tributaries over gravel beds at night and returned the lake by dawn. Each spring in tributaries of Lake Superior anglers gather with dip nets in hand. Smelt move into the small streams usually in mid April to spawn. Peak movement occurs when the water temperature lies between 42 and 44°F. This tradition appears immemorial, but smelt were introduced into the lake in early 1900s. To enjoy this activity, put on wadders, walk into 42° water with your dip net, dip smelt, and bite off the head of the first smelt you catch, to ensure good luck.


Climate effects on birds: The vast difference in weather patterns from one spring to the next is illustrative of the confusion that still persists when discussing climate change. The media, in general, is the primary catalyst for this confusion simply by their preferred doctrine of presenting two and only two sides to any story. Looking for the quick two-sided sound bite has resulted in a much diminished trust in and understanding of the scientific method, which involves multiple avenues of inquiry. Tomes have been printed on climate data, modeling of potential changes and denial of climate change.


In this article, GNW narrows the discussion to Wisconsin birds and birders. Therefore, a stage must be set, because the terms weather and climate are used throughout and an understanding of meaning is in order.


Weather patterns for any day or season cannot be used to prognosticate long-term climate effects. Weather is short-term and describes atmospheric conditions at certain place for a certain amount of time. Persons who study weather are meteorologists. Climate describes the average conditions over a longer timeframe, quite often defined as more than 30 years. Persons who study climate are climatologists.


Ornithologists studying weather or climate impacts on birds will many times find different effects as illustrated in the following table.


















Climate effects analysis on bird migration has utilized eBird data. Many studies have shown shifts in migratory phenology, but to date the data has reported much variation in the magnitude of responses. One study utilizing long-term data from eBird found 18 species of birds shifted their arrival dates between 0.8 days and 6 days for each 1 degree Celsius increase in temperature. It also found for species that migrated short distances or those with broad ecological niches were the earliest migrants.


These researchers conducted a study of 18 species over a large geographic area. They found that eBird data entered by citizen scientists was a means to start the process of understanding migration speed.  Their time frame of only ten years doesn’t quite meet the long-term definition of addressing climate, but it’s the best we have for answering some research questions. Waiting 20 more years of data may be much too late for some species.


The questions that comes to most birder’s minds is either “How can I help?” or “What good is my participation in citizen-base science monitoring, if we need 20 more years of data to make a decision?”  Both responses are nearly the same. Let’s look at the second question first. The core of this question revolves around the concept that we need all the answers before we can make a decision. Remember, the continual erosion of trust and understanding of the scientific method. 


Science involves use of mathematics, especially probabilities, to provide interpretation and give context to the data. Developing models give us the best method of describing the essential concepts required to answer the scientific questions to as close to 100% as possible within the limitations of the data. Better and more robust data gives us an even higher percentage of confidence that the predictions are accurate. I always find it enlightening to know gravity is not 100% proven, but everyone on earth believes in gravity.  


How can I help? Continue birding and submitting your sightings. Especially important for migration studies are sightings during or immediately after out of the ordinary weather events. More robust data is important for a better understanding of how bird life works.


Probably, a more important activity for birders is to convey the message to others. An incredible avenue for getting the message out is Migratory Bird Day. This worldwide event focuses attention on migratory birds. All aspects of the perils and benefits migratory birds that accrue through this remarkable migratory activity can be catalyst for understanding. Lay persons and sometimes, politicians can be enlightening. Positive messages about our beloved birds and what we can do help them respond to a changing climate is most likely much greater than any data we gather.  Please consider participating this year.



  • The Big Dipper reaches its highest point in the sky.

  • Watch for Northern Harrier courtship flights during evening hours over extensive grasslands.

  • Peak migration occurs for these species: Red-throated Loon, Blue-winged Teal, Greater Scaup, White-winged Scoter, Red-breasted Merganser, Purple Martin, Tree Swallows - in northern Wisconsin, Winter Wren, Hermit Thrush, Fox Sparrow, Vesper Sparrow, Rusty Blackbird, Brown-headed Cowbird, Horned Grebe, and Double-crested Cormorant.

  • In woods, look for early development of spring flora. Check out the forest floor for wild leak leaves, early blooming species such as wild ginger, snow trillium, spring beauty, rock cress, and trailing arbutus.

  • Mid-April is usually peak spawning time for rainbow trout.

  • In the north woods, search for Common Raven nests.

  • Mid-April is peak time for Saw-whet Owl calling. In many Northwoods conifer forest, they can be heard all night long uttering their too-too-too calls.

  • Louisiana Waterthrush arrives on nesting territories.

  • Check grasslands especially on warm rocky slopes, for newly emerged snake species such as Eastern hognose snake and blue racer.

  • This timeframe usually coincides with peak Ruffed Grouse drumming activity.

  • Greater Prairie-chicken courtship continues in central Wisconsin.

  • Elm stamens appear.

  • Female bumblebees emerge in the Northwoods.

  • Check open sandy areas for newly developed pig ear cup fungi.





  • Change or shift in range

  • Change in migration patterns

  • Narrowing of environmental range

  • Timing of prey species

  • Timing of predator species

  • Timing of nuisance species

  • Drying of prarie potholes

  • Selctive population differences




  • Individual or population deaths

  • Individual breeding fitness

  • Migrants blown off course

  • Local survival due to rain, ice, or snow

  • Parasite response to local weather

  • Migrant use of favorable winds

  • Metabolic rates

  • Courtship patterns


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