April 21 - 30
Racine has 14 hours and 3 minutes of daylight and Superior has 14 hours and 22 minutes of daylight at the end of the period. Southern Wisconsin gains 26 minutes of daylight and northern Wisconsin has 30 minutes more than the previous period.
Effect of cold spring weather on birds and birders: Spring migrations 2011 and 2014 were considered by birders as outstanding years for migrating warblers, vireos and tanagers, as well as many other species. Huge numbers of birds reported by many as reminiscent of the “good old days”. No leaves to obscure the birds and most of the migrants were at eye level or below. The usual complaint of warbler neck was nearly absent from birders vocabulary this year. Rarely found spring migrants such as White-eyed Vireo, Yellow-throated and Prairie Warblers, Northern Mockingbird, Summer Tanager and Yellow-breasted Chats were surprisingly easy to find. Even megararities, Black-throated Gray and Townsend’s Warblers, with aid from our instant communication were seen by dozens of birders.
Birder communication sources and social networks glowed with superlatives regarding the joy birders felt. During the late-April through most of May portion of the spring migration, comments such as: the best migration in years, warblers were dripping off the shrubs, as good as the good old days, they were easy to see, what a great migration, and the migration was outstanding permeated the social media. Birders obviously loved being a birder in these two springs’.
Good for birders, but was this the best migration in years, really good for the birds? The answer is probably somewhere between fair to poor all the way through disaster. Let’s look at the effects these weather may have had on the birds themselves. To be successful and productive parents, birds must be fit when they arrive on their breeding grounds. They need to be able to defend their territories, attract and court mates, build nests, and avoid predators. They also need to arrive on their breeding grounds in a timely fashion to have their reproductive activities coincide with annual insect hatches, flowering phenology, and fruit development, for example. Less fit individuals will have a much more difficult time meeting these reproductive requirements.
Fitness on the breeding grounds starts with fitness at the end of their time on the wintering grounds. American Redstart reproductive success has been directly linked to winter habitat condition. This winter habitat needs to provide basic nourishment the individual needs to build fat reserves and protein mass prior to onset of migration. If they leave their winter grounds in suboptimal condition, additional stressors during migration can lead to reduced productivity, simply surviving or even death.
Migration habitat and food availability can take winter fit birds at migration onset and add additional fitness stressors. How successful migrating birds are at satisfying energy demands on route depends in large part on habitat quality. Restoration of fat loads is critical to continue the next stage of the migration. Delays resulting in a need to remain at a stopover for days to replenish fat loads could be a make or break situation regarding the critical timing needed for arrival on the breeding territory. Furthermore, the degree of testicular development can be affected by food availability during migration stopovers.
Limits to habitat quantity or quality can lead to food based competition. Concentration of migrants with similar dietary needs can also lead to increased competition. At stop over sites, high numbers of competitors make replenishing energy reserves more difficult due to a higher number of birds foraging on a limited number of prey.
Weather can add another level of stress. Obviously, birders have known this fact for decades. Observations of flattened tanagers by the dozens on roadsides make most birders cringe. Less obvious is the effect of eliminating most desired foraging areas. Spring migrants along the Kickapoo River preferred red and white oaks. They tend to focus on the emerging leaves and flowers that hold pollen, nectar and the insects that also feed on the pollen and nectar. During extremely cold and wet weather nary a warbler or vireo is found on their preferred foraging niche. Furthermore, some species such as Cape May Warblers will set up and defend localized food sources putting additional energy tapping requirements on a bird.
In my nearly 40 years of birding, I have witnessed cold spring conditions many times. My experiences have been in many habitats, but the most expressive conditions are apparent in floodplains. During weather induced stressful migrations, warblers, vireos, tanagers, flycatchers, and others forage within a few feet of the ground. Especially conspicuous is foraging next to or over ephemeral ponds. Water temperature does not fluctuate as dramatically as land, thus insect hatches appear more consistent providing some sustenance for the migrants. This food source may or may not provide the necessary fat resources leading to successful breeding. More research is necessary.
What do we know - stopover habitat is very important for successful reproduction of or migrant birds. We also know habitat quality and diversity is important. Naturalists and birders can help by attaining knowledge of the importance of stopover habitat and supporting programs focusing on this habitat.
Spring Ephemerals: Spring ephemeral describes the life habit of perennial woodland wildflowers, which develop aerial parts each spring, quickly bloom, produce seed, and often die back to only underground structures or seeds. Many species considered ephemeral though maintain their leaves and grow throughout the summer, such species as May apple, wild geranium, and bloodroot fall into this category. The species that die back after setting seed and exhibit true ephemeral characteristics are species such as Dutchman’s breeches, white and yellow trout lily, spring beauty and false mermaid.
The almost unusual ephemeral form in rich wood lands is an orchid called the puttyroot or Adam and Eve orchid. In late fall, a single leaf appears above ground as the forest tree leaves fall. It remains green throughout the winter and spring until the new tree foliage becomes dense again. In late April into early May, the putty root orchid leaves wither. By mid-June a single flower stalk emerges and the orchid blooms.
Table 1: Species Normally Reaching Peak Blooming in Southern and West Central Wisconsin April 21 – 30.
Lyrid Meteor Shower: The Lyrids will peak on April 22. This meteor shower is considered the oldest known meteor shower; it is associated with the comet Thatcher, which has an orbit of 415 years around the Sun. The Lyrids are named after the constellation Lyra. The radiating point of this meteor shower is the sky around the star Vega, one of the brightest stars in the sky during this time of the year. The best time to watch is after midnight on April 22.
Rabbit and Hare Mating: Late April can be a good time to observe the mating activities of snowshoe hare and cottontail rabbit. During the mating season, males often fight each other. The male and female also perform a kind of a mating dance. The male will chase the female. Eventually the female will stop, face the male, box him and with her front paws. At some point one of them will leap straight up in the air and then the other one will jump. Although, the eastern cottontail mates between February and September, April is often a good time to observe these activities. Snowshoe hare have similar mating activities. They touch noses and the male charge and chase the female. Individuals often thump their hind feet perhaps as an alarm signal. Snowshoe hares also perform guttural hisses at the conclusion of mating, grunt, snort, or growl in other contexts.
Spring migration: Late April is a great time to observe migrating hawks in Wisconsin. Species, such as Broad-winged Hawk can form large kettles circling out of the forest in the morning. Other species such as Sharp-shinned Hawk, Merlin, and rarely Swainson’s Hawk migrate at this time also. Exceptional numbers can be observed on prime movement days. These prime days consist of warm southerly breezes that the hawks can used to ride the thermals and easily move north. By observing the hawk movement over the period of several days, large numbers can be recorded. Upwards of 1000 hawks can be recorded in late April. The best locations for observing this spring hawk migration are along the bluffs of the Mississippi River.
Spruce Grouse: The Spruce Grouse is a rare bird of coniferous forests in Wisconsin and is found only in the northern most counties. Most Spruce Grouse are associated with black spruce/tamarack swamps lying adjacent to upland conifers of jack pine and white spruce. Mating occurs in spring with males performing flutter jump displays. The male chooses display sites on upland islands or the edge of conifer swamps. These flutter displays are oft times accompanied by very low hooting sounds.
Lake Sturgeon spawning: Each spring, thousands of Lake Sturgeon migrate upstream from Lake Winnebago to spawn in the Wolf River. When the sturgeon are spawning along the rocky shorelines, they are fairly oblivious to nearby human activity. Thus, being preoccupied with spawning, they are very susceptible to illegal harvest. Sturgeon spawning typically occurs in late April or early May as soon as the water temperature reaches 53°F. If the water levels are lower, the temperatures must reach a higher 58° for them to spawn. Volunteers of the Sturgeon Patrol guard the spawning fish 24 hours a day throughout the spawning season. Naturalists can volunteer to be Sturgeon guards during this critical time in their life cycle. This volunteerism allows close viewing of the sturgeon and also helps conserve the species.
Bat migration: Wisconsin has three species of woodland bats that regularly migrate through the state. These species (silver haired bat, eastern red bat, and hoary bat) are predominantly solitary woodland dwellers. In summer, they prefer to roost under bark and in hollow trees and forage in woodland areas. They usually roost a few meters above the ground. In winter, they hibernate in southern United States. The hoary bat are largest species, migrates all the way to Mexico to escape the cold. They are one of the few bats that emit echolocation calls that are of low enough frequency so humans can occasionally hear them. These three species are our solitary bats and do not roost in caves and mines. Our cave bats are very susceptible to white nose syndrome, which kills nearly every bat within a cave system. If we are to have bats in the future, these three species may hold the key. It’s highly problematic that the cave species will ever have huge numbers again.
Reptile emergence: Late April is an outstanding time to observe reptiles emerging from their winter torpor. Two excellent examples are the timber rattlesnake and the five-lined skink. Both these species emerge from their hibernation sites and warm on rocks in late April. Both species are very limited in their range. The rattlesnakes are almost exclusively found on bluffs along the lower Wisconsin and Mississippi Rivers. They have become extremely difficult to locate due to persecution over the years. Five-lined skinks are found in the far northwest part of the state on rocky outcrops and sandy barrens.
In addition to hawk migration, these species reach their peak numbers in late April: Virginia Rail, Sora, Bonaparte’s Gull, Greater Yellowlegs, Chimney Swift, Bank Swallow, Ruby-crowned Kinglet, Blue-gray Gnatcatcher, Yellow-rumped Warbler, Eastern Towhee, Chipping Sparrow, Savannah Sparrow, Yellow-headed Blackbird, Brewer’s Blackbird, and Pied-billed Grebe.
Sharp-tailed Grouse courtship activity reaches its peak intensity.
Wild Turkey courtship reaches its peak activity.
Leopard frogs begin egg laying.
Check the log debris along major rivers in southern Wisconsin for basking map turtles.
Check small streams in far Southwest Wisconsin for Iowa darter mating activity. They can be observed in shallow riffles with males displaying colorful patterns.
As northern Wisconsin lakes open, walleye and muskellunge spawning reaches its peak.
Porcupine pups are born.
Naturalists should keep your eye on the trails through the woods and fields for newly emerged adult ground beetles. Species such as caterpillar hunter Calosoma scrutator and fiery hunter C. calidum may be seen crawling along the ground. These two species are some of our largest ground beetles and are very effective predators on caterpillars and other insects. They overwinter as adults and become active in late April.
Spring azure butterflies are common throughout Wisconsin. There especially frequent in wood lands and swamps. In late April, naturalist should be on the lookout for adults flying about looking for perches. They deposit their eggs on numerous plants including dogwood, sumac, and blueberry.
If a naturalist finds a grasshopper in late April, it would most likely be a green striped grasshopper or a spring yellow winged grasshopper. Both these species are found in open wood lands with a grassy understory, fields, prairies and roadsides. Nymphs overwinter and adults can be observed starting in late April.
Surprising to many people is the fact that Willets are regularly migrant occurrences in late April. These species, which nest in the Great Plains and along the oceans, especially the Atlantic Ocean have a small population that nests along Hudson Bay. This Hudson Bay population is estimated to be approximately 1500 individuals. It is these individuals moving towards Hudson Bay we get the pleasure of seeing each year in late April.
Traditional ice out on Trout Lake in Vilas County occurs in late April.
Two early species of mushroom to be looked for in late April are the horsehair mushroom and the manure mushroom. These species are tiny parasol shaped fungi found on decaying logs or manure.
Naturalist observing near water or paddling on rivers should keep your eye out for Northern water snake as they usually emerge in late April. They can be found basking on logs at this time. Late April is peak time for Blanding’s turtles to mate. Look for the bright yellow throats of the turtles as they bask on emergent logs and vegetation.
Most early flying moths are difficult for most naturalists to distinguish. One species, the double-toothed prominent, however, can be easily identified. A blackish line with two teeth on it separates the forewing into two parts. The lower half is grayish brown and the upper half is a dark brown. This species larva feeds on elms and is now most commonly found in floodplain forests.
White & Yellow Trout Lily
Virginia & Carolina Spring Beauty
False Rue Anemone
A few Species of Juneberry
Seeps - Alder Thickets
Moist Woodland and Forest
Dry to Moist Woodlands
Rich Soil in Dry to Mesic Woods
Gardens and Floodplain Forests
Dry to moist Woods
Woods and Floodplains
Sand Prairie and Barrens
Sandy to Dry Prairies
Fields, Pasture, Ditches
Woods & Wetlands