Hummingbirds are a beloved sign of spring and summer in Wisconsin, brightening gardens and yards with their flashy plumage and energetic antics. However, like all migratory birds, hummingbirds do not stay year-round, leaving when cold weather approaches in fall. This leads to the common question from bird lovers in Wisconsin – just how long do hummingbirds stick around before migrating south?
The answer depends on a few key factors:
What hummingbird species are present in Wisconsin?
Wisconsin hosts several species of hummingbirds through spring and summer:
– Ruby-throated Hummingbird: Most common and widespread species seen in the state. They breed and nest in Wisconsin.
– Rufous Hummingbird: Regular spring/fall migrant that occasionally spends summers in Wisconsin.
– Calliope Hummingbird: Rare spring/fall migrant, very seldom seen in summer.
– Broad-tailed Hummingbird: Extremely rare vagrant, with only a couple Wisconsin records.
So when discussing hummingbird seasons in Wisconsin, Ruby-throated Hummingbirds are the focus as they make up the majority of the state’s hummingbird population.
When do hummingbirds arrive in Wisconsin?
Ruby-throated Hummingbirds usually arrive in Wisconsin in early May. The first arrivals appear along the southern border and coastlines of Lake Michigan by early-mid May. They then spread northward through the state over the rest of May, reaching northern counties by late May or early June.
Here are the typical first sighting dates in Wisconsin cities, per Wisconsin bird records:
| City | Average First Arrival Date |
|---|---|
| Madison | May 13 |
| Milwaukee | May 6 |
| Green Bay | May 19 |
| La Crosse | May 8 |
| Wausau | May 17 |
| Eau Claire | May 14 |
These arrival dates can shift earlier or later by 1-2 weeks depending on spring weather patterns each year. But mid-May is the average expectation for the first hummingbirds to return.
When do hummingbirds leave Wisconsin in fall?
Hummingbird departure is more variable than arrival, as it depends on food availability. Generally, most Ruby-throated Hummingbirds leave Wisconsin by mid-late September. However, some individual birds may linger into October or rarely even November if they have a reliable food source.
Here are the typical final fall sighting dates for hummingbirds in Wisconsin:
| City | Average Final Sighting Date |
|---|---|
| Madison | September 11 |
| Milwaukee | September 19 |
| Green Bay | September 5 |
| La Crosse | September 15 |
| Wausau | September 8 |
| Eau Claire | September 12 |
Again, these departure dates can vary significantly based on food, weather, and individual bird behaviors. But most Wisconsin hummingbird watchers can expect their last sightings in mid-late September.
How long do hummingbirds stay in Wisconsin?
Combining average first arrival and final departure dates, hummingbirds generally spend 4.5-5 months in Wisconsin on average, seen from approximately:
– Madison: May 13 to September 11 = 4 months
– Milwaukee: May 6 to September 19 = 4.5 months
– Green Bay: May 19 to September 5 = 3.5 months
– La Crosse: May 8 to September 15 = 4 months
– Wausau: May 17 to September 8 = 4 months
– Eau Claire: May 14 to September 12 = 4 months
So while arrival and departure dates may vary across the state, most areas host hummingbirds for 4-5 months of the year.
What triggers hummingbird migration?
Hummingbird migration is triggered by a mix of biological instincts and seasonal cues like changes in daylight, temperature, and food availability. Here are some key factors:
Day Length
Hummingbirds respond to daylight length, which stimulates biological impulses to migrate north in spring and south in fall. As days lengthen in spring, hummingbirds begin moving northward. As days shorten in fall, they start migrating south.
Temperature
Hummingbirds cannot survive cold winter temperatures, as they are specially adapted for hovering flight which requires huge amounts of energy and therefore high food consumption. As temperatures drop in fall, food becomes scarce and hummingbirds migrate before they run out of sources.
Food Availability
Access to nectar-producing flowers and sap flows is key for hummingbirds. In spring, they follow the bloom line north as more flowers open. In fall, they leave when flowers die off and sap ceases to flow as plants enter dormancy. Lack of food forces migration.
Internal Clock
Hummingbirds appear to have an internal clock or rhythm that contributes to migration timing. Even in controlled experiments with fixed daylight and food, hummingbird activity levels and restlessness rises and falls on a seasonal cycle, indicating an innate biological clock.
So both external factors like weather and food, and internal genetic programming, guide hummingbird migration patterns in Wisconsin.
What do hummingbirds do in Wisconsin?
During the summer breeding season, hummingbirds are very active and energetic in Wisconsin as they engage in key behaviors:
Establishing Territories
Male hummingbirds returning in spring establish breeding territories with reliable food sources that they aggressively defend from intruders. Fights between males over territories are common.
Attracting Females
Males perform elaborate courtship displays to attract females to their territories, including aerial U-shaped or J-shaped dives and shuttle flights back and forth. High energy is required to impress females.
Mating
Once paired, hummingbirds mate frequently throughout the summer to produce multiple broods. The mating act only lasts seconds but occurs repeatedly.
Nest Building
Females build tiny cup nests only about 2 inches wide using soft plant down, spider webs, and lichens bound with sticky saliva. Nests may be re-used for multiple broods.
Incubating and Raising Young
Females incubate the 2 pea-sized eggs for about 2 weeks, and then care for the chicks for another 2-3 weeks until fledging. The chicks are fed regurgitated nectar and insects. Males do not participate in child-rearing.
Feasting on Flowers and Feeders
Hummingbirds have a hyperactive metabolism and require constant eating while active in Wisconsin. They feast on nectar from both native flowers and backyard feeders, consuming up to double their weight in nectar daily.
So spring through fall is an extremely busy and demanding time for Wisconsin’s hummingbirds as they breed and raise young.
How do hummingbirds behave in late summer/fall before migrating?
In late summer and fall, hummingbird behaviors change as birds prepare to migrate south:
Gorging on Food
Hummingbirds go into hyper feeding mode, dramatically increasing food intake to put on fat reserves needed to fuel migration and survive harsh weather during the journey. Food sources become critical.
Competing Aggressively at Feeders
Due to pre-migration gorging, late summer brings intense competition and aggression at feeders as hummingbirds fight fiercely to maintain access. They guard feeders obsessively.
Frantic Territorialism and Courtship
Some late nesting efforts may occur, with frantic males aggressively defending territories and courting females. These late-season behaviors are shorter and more hurried.
Restlessness and Dispersal
As migration nears, hummingbirds appear restless and may wander far from typical ranges exploring food options. Dispersal from regular sites increases through late summer.
Migrating South
By mid-September, most hummingbird behaviors related to breeding and summer activities subside as birds begin migrating south in short hops by night. Energy is focused on migration.
So late summer hummingbird behaviors serve to maximize food intake, fat stores, and energy to fuel an arduous migration ahead.
Conclusion
To summarize key points:
– Wisconsin hosts Ruby-throated Hummingbirds from approximately mid-May through mid-September, with some individuals remaining into October during some years.
– Hummingbird migration is driven by biological impulses responding to changes in daylight, temperature, food availability and internal rhythms.
– While in Wisconsin, hummingbirds are very active with behaviors related to breeding including territory defense, courtship, mating, nesting and raising young. High energy requirements necessitate constant feeding.
– In late summer and early fall, behaviors shift to hyper feeding, aggression at feeders, restlessness, and pre-migratory dispersal before embarking on their long migration to Central America and Mexico.
So hummingbird watchers in Wisconsin can enjoy the sight of these energetic, colorful birds gracing backyards and gardens for about 4-5 months each year, bringing the joys of spring through late summer before they must leave on their incredible migration south. Providing nectar feeders and native plants will help attract and sustain hummingbirds during their active but brief stay in the state. With careful observation, one can note their behavioral changes throughout the season as they breed, raise young, bulk up for migration, and finally depart in fall. Watching and supporting hummingbirds provides an ideal way to connect with nature close-up during the warmer months in Wisconsin.
