Rio Bosque Wetlands Biological Treasure Hunt

The mourning dove is a medium-sized, slender dove approximately 31 cm (12 in) in length. Mourning doves weigh 112–170 g (4.0–6.0 oz), usually closer to 128 g (4.5 oz). The elliptical wings are broad, and the head is rounded. Its tail is long and tapered ("macroura" comes from the Greek words for "large" and "tail"). Mourning doves have perching feet, with three toes forward and one reversed. The legs are short and reddish colored. The beak is short and dark, usually a brown-black hue.

The plumage is generally light gray-brown and lighter and pinkish below. The wings have black spotting, and the outer tail feathers are white, contrasting with the black inners. Below the eye is a distinctive crescent-shaped area of dark feathers. The eyes are dark, with light skin surrounding them. The adult male has bright purple-pink patches on the neck sides, with light pink coloring reaching the breast. The crown of the adult male is a distinctly bluish-grey color. Females are similar in appearance, but with more brown coloring overall and a little smaller than the male. The iridescent feather patches on the neck above the shoulders are nearly absent, but can be quite vivid on males. Juvenile birds have a scaly appearance, and are generally darker.

All five subspecies of the mourning dove look similar and are not easily distinguishable. The nominate subspecies possesses shorter wings, and is darker and more buff-colored than the "average" mourning dove. Z. m. carolinensis has longer wings and toes, a shorter beak, and is darker in color. The western subspecies has longer wings, a longer beak, shorter toes, and is more muted and lighter in color. The Panama mourning dove has shorter wings and legs, a longer beak, and is grayer in color. The Clarion Island subspecies possesses larger feet, a larger beak, and is darker brown in color. less ↑

Adult killdeer range in length from 23–27 cm (9.1–10.6 in) with a wingspan averaging 17.5 cm (6.9 in). The largest ringed plover, killdeer weigh 88 g (3.1 oz) on average.

Killdeer have a characteristic large, round head, long tail, long flesh-colored legs, and long wings. The bill is short, dark, and thick. Plumage is brownish-tan on dorsal areas and white on the ventral belly and chest; the neck is also surrounded by a white collar. Two large, dark bands surround the upper breast with an additional band located on the head, spanning both the forehead and the area above the bill and continuing around the back of the head. The tail is brown with a black subterminal band, a white terminal band, and white outer tail feathers. Additional defining plumage characters include a brightly colored red-orange rump that is visible during flight and displays, white wing stripes visible during flight. Appearance does not vary between males and females, although breeding females may have additional brown plumage on the head. Juveniles resemble adults with the exception of buff fringe feathers and the presence of only one neck band

C. v. ternominatus

Cuba

C. v. ternominatus

Cuba less ↑

Adults have long pink legs and a long thin black bill. They are white below and have black wings and backs. The tail is white with some grey banding. A continuous area of black extends from the back along the hindneck to the head. There, it forms a cap covering the entire head from the top to just below eye-level, with the exception of the areas surrounding the bill and a small white spot above the eye. Males have a greenish gloss to the back and wings, particularly in the breeding season. This is less pronounced or absent in females, which have a brown tinge to these areas instead. Otherwise, the sexes look alike.

Downy young are light olive brown with lengthwise rows of black speckles (larger on the back) on the upperparts – essentially where adults are black – and dull white elsewhere, with some dark barring on the flanks.

Where their ranges meet in central Brazil, the black-necked and white-backed stilts intergrade. Such individuals often have some white or grey on top of the head and a white or grey collar separating the black of the hindneck from that of the upper back.

The black-necked stilt is distinguished from non-breeding vagrants of the Old World black-winged stilt by the white spot above the eye. Vagrants of the northern American form in turn is hard to tell apart from the resident Hawaiian stilt, in which only the eye-spot is markedly smaller. But though many stilt populations are long-distance migrants and during their movements can be found hundreds of miles offshore, actual trans-oceanic vagrants are nonetheless a rare occurrence. less ↑

As is the case with many raptors, the red-tailed hawk displays sexual dimorphism in size, as females are up to 25% larger than males. As is typical in large raptors, frequently reported mean body mass for Red-tailed Hawks are somewhat higher than expansive research reveals. Part of this weight is highly seasonally variable and due to clinal variation, male red-tailed hawks may weigh from 690 to 1,300 g (1.52 to 2.87 lb) and in females between 900 and 2,000 g (2.0 and 4.4 lb). However, research from nine studies occurring at migration sites in the United States and two breeding studies, one from the smallest race in Puerto Rico, the other from larger races in Wisconsin show that males weigh a mean of 837 g (1.845 lb) and females weigh a mean of 1,040.7 g (2.294 lb), about 15% lighter than prior species-wide published weights. The heaviest surveyed weights came from migrants in Cape May, New Jersey, where females weighed a mean of 1,278 g (2.818 lb), males a mean of 990.8 g (2.184 lb). The lightest were from the breeding population in forest openings of Puerto Rico, where the females and males weighed an average of 1,023 g (2.255 lb) and 795 g (1.753 lb), respectively, also the highest size sexual dimorphism in the species. Size variation in body mass reveals that the red-tailed hawks typically varies only a modest amount, racial variation in average weights of great horned owls show that mean body mass is nearly twice (the heaviest race is about 36% heavier than the lightest known race on average) as variable as that of the hawk (where the heaviest race is only just over 18% heavier on average than the lightest). Males can reportedly measure 45 to 60 cm (18 to 24 in) in total length, females measuring 48 to 65 cm (19 to 26 in) long. The wingspan can range from 105 to 141 cm (41 to 56 in) and, in the standard scientific method of measuring wing size, the wing chord is 325.1–444.5 mm (12.80–17.50 in) long. The tail measures 188 to 258.7 mm (7.40 to 10.19 in) in length. The exposed culmen was reported to range from 21.7 to 30.2 mm (0.85 to 1.19 in) and the tarsus averaged 74.7–95.8 mm (2.94–3.77 in). The middle toe (excluding talon) can range from 38.3 to 53.8 mm (1.51 to 2.12 in), with the hallux-claw (the talon of the rear toe, which has evolved to be the largest in accipitrids) measuring from 24.1 to 33.6 mm (0.95 to 1.32 in) in length.

Red-tailed hawk plumage can be variable, depending on the subspecies and the region. These color variations are morphs, and are not related to molting. The western North American population, B. j. calurus, is the most variable subspecies and has three color morphs: light, dark, and intermediate or rufus. The dark and intermediate morphs constitute 10–20% of the population.

Though the markings and hue vary across the subspecies, the basic appearance of the red-tailed hawk is consistent. Overall, this species is blocky and broad in shape, often appearing (and being) heavier than other Buteos of similar length. A whitish underbelly with a dark brown band across the belly, formed by horizontal streaks in feather patterning, is present in most color variations. Especially in younger birds, the underside may be otherwise covered with dark brown spotting. The red tail, which gives this species its name, is uniformly brick-red above and light buff-orange below. The bill is short and dark, in the hooked shape characteristic of raptors, and the head can sometimes appear small in size against the thick body frame. They have a relatively short, broad tails and thick, chunky wings. The cere, the legs, and the feet of the red-tailed hawk are all yellow.

Immature birds can be readily identified at close range by their yellowish irises. As the bird attains full maturity over the course of 3–4 years, the iris slowly darkens into a reddish-brown hue. In both the light and dark morphs, the tail of the immature red-tailed hawk is patterned with numerous darker bars. less ↑

The adult Say's phoebe is a drab, chunky bird. It is gray-brown above with a black tail and buffy cinnamon below, becoming more orange around the vent. The tail is long and the primaries end just past the rump on resting birds. The wings seem pale in flight and resemble a female mountain bluebird. The juvenile is similar to adult, but has buffy orange to whitish wingbars and a yellow gape. Adult birds are 7.5 in (19 cm) long. They have a 13 in (33 cm) wingspan and they weigh 0.75 oz (21 g). less ↑