Black-crowned Night-Heron chick
Certain waterbird species typically breed in colonies. Preferred spots to find colonial nesters are sites that are protected from predation like an island, a lakeshore, a beaverpond, or even in the cases of some gulls, the roof of a building. Because breeding only occurs in colonial situations, seeing these species in your block is not necessarily indicative of local breeding because they range widely, and therefore codes like H and P are generally not useful for these species. Similarly, FL and FY codes away from nest sites are not reliable because these species disperse widely once fledged.
Check out the tips in this article and then check the blocks around you for some colonial waterbirds!
Great Egret
Great Egret photo by Tom Prestby
Profile: The state-threatened Great Egret breeds at the northern edge of its continental range in Wisconsin. Great Egrets nest typically in trees, often with Great Blue Herons, sometimes with Double-crested Cormorants, inhabiting marshes, swamps, inland lake islands, and coastal islands primarily in east-central counties, in Green Bay, intermittently at Horicon Marsh, and at scattered sites along the Mississippi River. They also nest in shrubs, and in recent years have occupied at least one interior lake island cattail marsh, nesting on windrowed stems. Vocalizations include a loud, low croaking “cuk-cuk-cuk,” commonly heard when the bird is disturbed and takes to flight.
WBBA I Breeding Range
Arrival: Early to mid-April, extending into May, except along the Mississippi, where birds may appear by late March. Breeding: Nest – a platform style of sticks in tree or tall shrub. Will re-nest if first nest fails. Clutch size: 1 to 6 eggs, with an average clutch size of 3. Dates for nests with eggs in Wisconsin range from May 7 to June 23. Incubation: 23-27 d; Fledging: 21 d. Parents continue to feed young until age 62-67 days old.
Focal Habitat: The Great Egret will nest in trees and shrubs in large marshes and other wetlands. It chooses sedge marshes, shallow lakes and lakeshores, and creeks, sloughs, and oxbow ponds associated with floodplain sites, as well as Waterfowl Production Areas, for feeding and foraging in Wisconsin. Birds forage at distances ranging from 16-20 km (~10-13 mi) away from breeding colonies. Some feeding may occur in flooded fields, or in ponds, steams, canals, ditches, and at ponds used for commercial fish production. Both nesting and foraging sites are often shared with Great Blue Herons, and nesting colonies often contain nests of both species, and occasionally cormorants.
Code Guidance: When near a suspected colony (indicated by egrets entering and leaving a site), use NB for birds observed building nests, C when copulation is observed, and ON for birds sitting on nests. Use NY later in summer when pre-fledglings are observed (seen or heard) at a nest site from a distance (50 m or greater) that will not cause disturbance. Beware use of FL late in the season as this species can disperse widely when fledged.
Similar Species and Fledgling/Juvenile ID: Snowy Egrets resemble Great Egrets but are smaller and have bright yellow feet—the so-called “golden slippers,” a slender black bill, and bright yellow lores (in alternate plumage). Great Egret fledglings show an even and smooth “herring-bone” pattern on the neck (Adults usually show signs of molt on the neck, with small gaps where feathers are missing; herring bone pattern may appear only faintly on the back of the neck.). Juveniles feature back and scapular feathers that are short and rounded, with distinct edges and a smooth and scaled pattern. Adults have longer back feathers tapered to a point, and very long plumes on the back, which gives the whole back a silky/hairy texture rather than scaly. The tips of the adult tail are often stained slightly orange by late summer. Also, juveniles show no gaps or irregularities in the wing coverts, and no sign of molt or worn, damaged wing coverts as you’ll see in adults. There are no reliable differences in bill color or eye color between adult and juvenile Great Egrets, but juveniles do tend to show paler brownish color at the top of the legs (vs blackish on adults).
More information about Great Egrets:
All About Birds
eBird Range Map
Birds of North America Account (subscription required).
Great Blue Heron
Great Blue Heron photo by Nick Anich
Profile: The Great Blue Heron occurs throughout Wisconsin and is the largest (60 cm or 24 in tall; 97-137 cm or 38-54 in long) wading bird in North America, with its mostly blue-gray plumage, white crown, long bill, and long and rounded wings. Its flight is distinctive with wingbeats deep and slow, and with its neck folded in an S-shape when it flies. Great Blue Herons nest typically in rookeries/colonies in mature trees statewide (often with Great Egrets in east-central counties), inhabiting marshes, swamps, inland lake islands, coastal islands, wooded coastal peninsulas, and other upland forest types. They have also nested (rarely) on iron ore dock remnants. Vocalizations include a variety of squawk calls of different durations commonly heard at the rookery site or when feeding. Great Blue Herons feed in shallow water by slowly wading or by standing and waiting for prey, which is usually fish, amphibians, reptiles, and invertebrates, but also may include small mammals and birds.
WBBA I Breeding Range
Arrival: mid-March to early April in southern WI; 2 weeks later in the north. Breeding: Nest – a platform of sticks and twigs in tall tree or shrub. Nest built in 3 d to 2 wks. May re-nest if first nest fails. Nests often re-used for many years. Clutch size: 2 to 6 eggs, with an average clutch size of 4. Dates for nests with eggs in Wisconsin generally range from April 20 to 10 May. Incubation: about 27 d; Fledging: 51-60 d. Parents continue to feed for 21 d after fledging.
Focal Habitat: Often mature hardwoods (typically eastern cottonwood, shagbark hickory, red oak, white oak, swamp white oak, and elm) in large marshes, swamps, and other wetlands, upland woods, and on lake islands; sometimes in conifers associated with lakes, ponds, streams.
Code Guidance: When near a suspected colony (indicated by herons entering and leaving a site), use N for “probable nest/colony site,” C when copulation is observed, and ON for birds sitting on nests. Use NY later in summer when pre-fledglings are observed (seen or heard) at a nest site from a distance (50 m or greater) that will not cause disturbance. Beware use of FL late in the season as this species can disperse widely when fledged.
Similar Species and Fledgling/Juvenile ID: This species is the largest heron in North America and usually can’t be confused with another species (Little Blue Herons are similarly dark in appearance but much smaller in size), except in flight, when it is sometimes confused with a Sandhill Crane, (cranes fly with an outstretched neck, compared to the Great Blue Heron’s tucked in neck). Fledglings/Juveniles have a brownish appearance, with a rust-brown edging to the back and wing coverts, and grayish crowns.
More information about Great Blue Herons:
All About Birds
eBird Range Map
Birds of North America Account (subscription required).
Black-crowned Night-Heron
Black-crowned Night-Heron photo by Nick Anich
Profile: The Black-crowned Night-Heron is locally uncommon and breeds primarily in eastern, northeastern, southeastern, and east-central Wisconsin, though observations have been known to occur outside this region. It is a medium-sized heron (length: 58-66 cm or 23-26 in; wingspan: 115-118 cm or 45-47 in), stocky with a short neck and legs. It has a distinctive black cap, upper back, and scapulars, gray wings, rump, and tail, black bill, red eyes, and pink legs during the breeding season. This bird is most active at night, with crepuscular feeding habits. Black-crowned Night-Herons nest colonially, often occurring in mixed heron colonies in the lower branches of trees associated with wetlands and water bodies (typically inland lakes, marshes, and coastal islands). They have also nested in dense cattail stands. Vocalizations include a variety of squawk or woc calls of different durations commonly heard at the rookery site or when feeding.
WBBA I Breeding Range
Arrival: Early April to early May. Breeding: Nest – typically a shabby platform of sticks in a tree or shrub. Nest construction can occur by late April or early May, with eggs present certainly by late May and as early as the first week of May. WBBA I atlas observers noted eggs recorded by 26 May. May re-nest if first nest fails. Nests may be re-used in subsequent years. Clutch size: 3 to 5 eggs; sometimes as few as 1 or 2. Incubation: 24-26d; Fledging: 42-49 d. Parents continue to feed young apparently for several weeks post-fledging so observations of newly fledged young can provide confirmation of nearby nesting.
Focal Habitat: Woods and wetlands of inland lakes, and on islands, woodland edges, and marshes associated with Green Bay and Lake Michigan.
Code Guidance: When near a suspected colony (indicated by herons entering and leaving a site), use CN/NB for nest building activity and ON for birds sitting on nests. Use NY later in summer when pre-fledglings are observed (seen or heard) at a nest site from a distance (50 m or greater) that will not cause disturbance. Beware use of FL late in the season as this species can disperse widely when fledged.
Similar Species and Fledgling/Juvenile ID: This species is sometimes confused with a Yellow-crowned Night-Heron, which is uncommon to rare in Wisconsin, and is also a short, stocky heron with a wingspan of almost 4 feet and about 2 feet in length. Adult Yellow-crowneds, which can overlap with Black-crowneds in habitat selection, are grayish with a black head and notably contrasting white cheek patch, and a creamy-yellow crown and head plumes. Juvenile Black-crowneds have large pale spots on the back, scapulars, and coverts, a partially yellow bill, and are heavily streaked with brown on the underparts. By contrast, Immature Yellow-crowneds are grayer, with smaller white spots on the back and wings. Its bill appears heavier than immature Black-crowneds, and is all-black. One other distinguishing feature of the immature Yellow-crowned: It has longer legs than the immature Black-crowned, and when flying its feet extend well beyond the tip of the tail.
More information about Black-crowned Night-Herons:
All About Birds
eBird Range Map
Birds of North America Account (subscription required).
American White Pelican
American White Pelicans photo by Nick Anich
Profile: The American White Pelican is a large (Length: 127-165 cm or 50-65 in) white waterbird with black flight feathers, a huge, long, orangish bill and gular pouch, and orange legs. Early in the breeding season, both adults exhibit a flattened, epidermal “horn” on the upper mandible; this horn is later shed about the time eggs begin to hatch. Breeding adult vocalizations are silent, except for low grunts uttered in aggressive or sexual encounters. Nestlings utter loud, food-begging squaks or grunts. In Wisconsin, breeding American White Pelicans have almost exclusively occupied inland lakes, Horicon Marsh, and Green Bay/Lake Michigan, and have nested on isolated, permanent islands, dredge spoil islands, dikes, and edges of peninsular cattail stands. All colonies have occurred on the ground, either on bare ground, exposed dredge spoil or mud flat, on flattened cattail mats, or in the case of some Horicon NWR nests, at the base of shrubs.
WBBA I Breeding Range
Arrival: Early April to late May. Breeding: Nest – typically a shallow depression on bare ground, with little or no vegetation in nest cup. Nest construction occurs 4-5 days after nest selection, with eggs present at Horicon Marsh NWR nests as early as 6 May. Not known if re-nesting occurs. Nests not re-used. Clutch size: 2 eggs (2 days between first and second egg); rare larger clutch sizes due to retrieval of eggs that roll from nearby nests. Incubation: 30 d (2 days between hatching of first and second egg). Fledging: 63-70 d (First-hatched chicks grow significantly faster than second-hatched chick, which usually dies [siblicide]).
Focal Habitat: Isolated, permanent islands; dredge spoil islands; dikes; and edges of peninsular cattail stands at eastern and east-central inland lakes, Horicon Marsh, Green Bay/Lake Michigan, and possibly large sand bar islands along the Mississippi River.
Code Guidance: When near a suspected colony (indicated by a large gathering of adults on land), use ON for birds sitting on nests. Use NY later in summer when pre-fledglings are observed (seen or heard) at a nest site from a distance (50 m or greater) that will not cause disturbance. Pelicans readily leave nests unattended when approached by humans, and are relatively slow to return to a colony, so keep this in mind when evaluating whether or not to walk through a colony site, especially if gulls are nesting at the same site because both Herring Gulls and Ring-billed Gulls are predators of hatching pelican eggs and young chicks. Pelicans are often observed away from nesting areas, and because nesting only occurs in colonies, H is not meaningful for birds away from a suspected breeding site, and FL is not useful for this species, as fledglings disperse great distances from the nest site.
Similar Species and Fledgling/Juvenile Id: In flight, this species is sometimes confused with a Whooping Crane because they are both large white birds with black primaries, but the area of the wing with black differs. From a far distance, on the water, they are also sometimes confused with swans, but using binoculars one can quickly discern the difference. Juvenile American White Pelicans are dusky white, with a grayish crown, and a black wing pattern that resembles an adult at the time of fledging.
More information about American White Pelicans:
All About Birds
eBird Range Map
Birds of North America Account (subscription required).
Double-crested Cormorant
Double-crested Cormorant photo by Nick Anich
Profile: The Double-crested Cormorant is a common inhabitant of many of our inland lakes and Great Lakes’ coastal waters, but also breed in rivers, swamps, and impoundments. Adults (70-90 cm in length, or 28-35 in) have glossy black or dark-brown plumage and a bare, orange or orange-yellow throat pouch. Breeding adult vocalizations include deep, guttural calls and grunts, but they are otherwise silent. Nestlings utter food-begging chirps, and hiss when threatened by a potential predator. Breeding cormorants nest on the ground—on islands mostly, or cliffs; in trees—conifers or deciduous trees, shrubs, islands of cobble or small islands with boulders containing navigation signals, or on reefs, abandoned docks, breakwalls, artificial nest structures, and transmission line towers.
WBBA I Breeding Range
Arrival: Mid-April to late May. Breeding: Nest – Near water; nest constructed of finger-sized sticks, twigs, leafy stems from living plants, and lined with grass, rootlets, or similar material. Both adults build nests over 2-4 d, and first eggs are laid 2-4 wk after arrival, with much asynchrony at and between colony sites. Both sexes add nest material throughout incubation. Clutch size: 1-7 (modal clutch of 4). Incubation: 25-28 d. Fledging: 49 d (Young completely independent of parents by age 10 wk.).
Focal Habitat: Bare and vegetated Great Lakes islands and inland lakes, rivers, swamps, and impoundments.
Code Guidance: When near a suspected colony (indicated by a large gathering of adults on land), use CN/NB for nest building activities, and ON for birds sitting on nests. Use NY later in summer when pre-fledglings are observed (seen or heard) at a nest site from a distance (50 m or greater) that will not cause disturbance. Cormorants readily leave nests unattended when approached by humans, and are relatively slow to return to a colony, so keep this in mind when evaluating whether or not to walk through a colony site, especially if gulls are nesting at the same site because both Herring Gulls and Ring-billed Gulls are predators of cormorant eggs and young chicks. Note that because nesting only occurs in colonies, H is not meaningful for birds away from a suspected breeding site, and FL is not useful for this species, as fledglings disperse great distances from the nest site.
Similar Species and Fledgling/Juvenile Id: In flight, this species is sometimes confused from a distance with a Canada Goose or Common Loon. Juvenile cormorants have a dark brownish-gray to pale-brown head, a grayish-white chin, white or pale throat with brown mottling, dark grayish-brown upperparts, and mottled brown and white underparts; tail feathers are dark brown.
More information about Double-crested Cormorants:
All About Birds
eBird Range Map
Birds of North America Account (subscription required).
Ring-billed Gull and Herring Gull
Profile: The Ring-billed Gull is a cosmopolitan and familiar medium-sized white-headed gull (with a distinctive black ring around its bill) often seen at landfill sites, coastal parking lots, marinas, urban parks, and following behind farm tractors in the spring and fall. Ring-billeds commonly breed in east-central, northeastern, southeastern, and northwestern counties on barren or sparsely vegetated peninsulas and islands—natural and/or dredge spoil, of large inland lakes and Lakes Michigan and Superior. It often nests on the ground (rarely trees) in mixed colonies with Herring Gulls, cormorants, and pelicans, or some combination of those species.
Ring-billed Gull photo by Nick Anich
Herring Gulls, which appear bigger and bulkier side by side, frequent several of the same coastal areas and large inland lakes, and recently both have been known to colonize (separately) flat rooftops of coastal buildings. When nesting together with Ring-billeds, Herrings may select ground nest sites in the more vegetated (ground cover) portions of an island site. Adult Herring Gulls are about 60 cm in length (or 24 in), compared to about 50 cm (or 20 in) for Ring-billed Gulls. Herring Gulls nest colonially, but also singly on cliffs, and abandoned/seldom visited towers, bridge abutments, and light beacons in the Great Lakes.
Herring Gull photo by Nick Anich
Herring Gull adults at the colony site have a variety of vocalizations, but the most readily identifiable one is called the “Long Call” or “Trumpeting” which lasts several seconds and begins with the adult lowering its head and then raising it in repeated notes that grow louder in intensity. Ring-billed Gull adults have a similar Long Call, but it is higher pitched than the Herring Gull. Unlike Ring-billed Gulls, breeding Herring Gulls, which have eggs about to hatch or young chicks, won’t hesitate to swoop repeatedly and attack a human visiting a colony site. On Lake Superior, the Herring Gull is commonly observed trailing behind commercial fishing boats.
WBBA I Breeding Range – Ring-billed Gull
WBBA I Breeding Range – Herring Gull
Arrival: Mid-March to mid-May (RBGU); early March to late April (HERG). Breeding: Nest – RBGU nest constructed of dead plant material—twigs, sticks, grasses, leaves, lichens, and mosses, but sometimes contain almost no nest material. HERG nest bowl fashioned in scrape and lined with mosses, lichens, leaves, grasses, and sometimes feathers and twine. Both adults of both species build nests several days before egg-laying. HERG will add nest material throughout incubation. Clutch size: 2-4, typically 3 (RBGU); 1-3, typically 3 (HERG). Incubation: 23-28 d (RBGU); 30-32 d (HERG). Fledging: About 35 d (RBGU); about 50 d (HERG).
Focal Habitat: Ring-billeds prefer sparsely vegetated Great Lakes (artificial and natural) islands and large inland lake islands, and occasionally on peninsulas. Herrings prefer Artificial and natural Great Lakes islands and large inland lake islands; Great Lakes rocky islets, marshy hummocks, and barrier sand beaches; and sandstone cliffs of Lake Superior coasts. Either can also nest on the roofs of large buildings.
Code Guidance: When near a suspected colony or lone nest (HERG), use N for “probable nest/colony site,” CN for carrying nest material (a frequently observed code) and ON for birds sitting on nests. Remember to observe nest sites from a distance (50 m or greater) that will not cause disturbance. Note that because nesting only occurs in colonies, H is not meaningful for birds away from a suspected breeding site, and FL is not useful for this species, as fledglings disperse great distances from the nest site.
Similar Species and Fledgling/Juvenile Id: Adult RBGU and HERG look similar in flight, but are readily told apart when standing— adult RBGU have yellowish legs; HERG has pinkish legs. Adult HERG does not have a clean black ring across the bill, but instead has a red spot at the end of the lower mandible. Fledging RBGUs and HEGUs are similarly brownish in appearance, but the HEGU is almost uniformly brown; the RBGU has a subterminal, white tail band.
More information:
Ring-billed Gull
All About Birds
eBird Range Map
Birds of North America Account (subscription required).
Herring Gull
All About Birds
eBird Range Map
Birds of North America Account (subscription required).
Thanks to Sumner Matteson (WDNR) for preparing this account.