The White-eared Ground-sparrow (Melozone leucotis) is a medium sized passerine bird that is commonly associated with dense thicket habitat. It belongs to the family Emberizidae and is found in the genus Melozone a relatively understudied genus of Neotropical birds. This species has a distribution that is documented from Mexico to Costa Rica (Stiles & Skutch 1989). M. leucotis is known to have a long breeding and nesting season that can run from the end of March to September. This species is assumed to be socially monogamous, meaning these birds mate and rear chicks in unison during the breeding season but aren’t know to form life long partnerships. M. leucotis forages and nests in the understory of densely packed thickets in unmanaged secondary forest habitats on middle elevation, pacific slope of Costa Rica. This terrestrial species is thought to be omnivorous eating a wide range of dietary supplementation from insects to fruits (Sandoval & Mennill 2012). M. leucotis is a territorial species that has been described to have a year-long territory which average around 60 x 60 meters and range from circular to rectangular patterns (Sandoval & Mennill 2012, Luis Sandoval unpublished). The association with secondary forest area lends conservation issues to this species due to the fact that successional secondary thicket habitat is not well protected or managed in this species range (Sandoval & Mennill 2012). This could lead to loss in habitat for this species, which could cause conservation concerns later on.
This species is identifiable by its distinctive white supraloral spot (this is the area located above the lore; the lore is recognized as the area between the eye and the base of the beak) and white ear coverts. The throat and chest of the bird have black. The ventral region is marked by a white or off-white coloration. The primaries (the twelve most outer feathers on the wings), retrices (or tail feather), and remaining feathers on the back are drab olive/tan coloration. This species can commonly be heard rummaging through leaf litter in densely thicketed secondary forest or coffee plantations. The average length of M. leucotis is 18 cm (Garrigues & Dean 2014).
This species has a Mesoamerican distribution that ranges from Chiapas, Mexico to the Central Valley in Costa Rica. Melozone leucotis has been documented to inhabit elevations between 500 – 2000 meters (Stiles & Skutch 1989). The distribution in Costa Rica lies primarily in the Central Valley area. These birds are known to be fairly common from the Pacific slope of Tiláran .Cordillera, which is the southern extent of the range. The northern extent of the species range is the pacific slope of Chiapas only, in southern Mexico. In Mexico these birds are also known the inhabit forest undergrowth and forest border that extends upslope between 300 meters and the highlands (Peterson & Chalif 1973).
This species of bird has close ties to densely vegetated forest because of its foraging strategy and life history traits. Melozone leucotis is highly terrestrial and spends most of its time on the forest floor or perched on low hanging vegetation for territory surveillance and foraging. This species inhabits successional forest that has densely packed vegetation. M. leucotis prefers secondary forest edges, areas with abundance of dense thickets, and coffee plantations (Stiles & Skutch 1989). These habitats are not of much concern to conservationists and biologist so the amount of unmanaged secondary forest habitat decrease may have detrimental affects on this species (Sandoval & Mennill 2012). However, in the Costa Rican populations the Central Valley is experiencing high rates of development relatively. This is diminishing territory in their range that may lead to population declines.
Melozone leucotis has a long breeding season that has been recorded to have a duration lasting from March to September (Sandoval & Mennill 2012). In the range of the species that exist in Costa Rica the birds seem to have peak breeding in April and May. This would indicate this species breeds from the middle to late dry season and throughout the rainy season, with peaks in the early rainy season. Eggs were documented to have a white base with variable brown spotting on the eggshell. Eggs were documented to be 23-27 mm long (Sandoval & Mennill 2012). Two nesting types were discovered in the Costa Rica population. The traditional nest that was documented in the species is a densely woven cup nest that consists of loosely woven plant material that surround a tighter woven area consisting of plant material. These nests have been documented in many places including between main stems on trees, under leaves of a species of Araceae, ground under overhanging rocks, one upon exposed roots near trails, beneath group of dead branches, and the last between the leaves of a Dracaena sp. bush (Sandoval & Mennill 2012). It is proposed that this nest architecture may provide more answers for microhabitat selection and nest structure. The bulkier architecture nest was usually found in between branches of trees and off the ground. This suggests that the bulkier more padded nest may be because the birds are adjusting for increased protection of the eggs and to create a more ideal thermal environment (Sandoval & Mennill 2012). The second documented nest was created using loosely woven dead leaf petioles and thin plant fibers. Twice Sandoval and Mennill (2012) recorded this nesting type on the ground in a rocky substrate. This nest type may be an adaptation to creating a less conspicuous nest to lower predation rates because of its location on the ground. Another possible reason could be that the ground provides a firm substrate for the nest when compared to trees so the foundation of the nest is not as important (Sandoval & Mennill 2012). Females appear to be the only gender to incubate eggs in this species. It is documented that both parents will feed the hatchlings, however the female is the only parent to feed fledglings. Research has also indicated that the male may sing to females and fledglings as an indication as to where food is located. Interestingly, observed reports indicate that if an observer is near a nest the female will approach the observer producing a broken leg display and emitting harsh calls. Meanwhile, the male will stay within 2 -10 meters of the nest. After this display the female and male will return to duet and then sing solo songs (Sandoval & Mennill 2012).
White-eared ground-sparrows are highly territorial birds. This species has been observed to hold year-round territories as a pair of one male and one female. These territories have been described to be rectangular to circular in geometry and on average are about 60 m x 60 m (Luis Sandoval, unpublished). The duetting pair will actively defend their territory again conspecifics. In an ongoing study there has been observed behavior of aggression used against conspecific neighbors and strangers (S. Keyser, unpublished). This behavior can be characterized as the territorial male and female hearing a conspecific in their territory and then flying within approximately 10 meters of the individual. Once they have located the individual in the territory the pair will transmit short “tseet” call and then both will perch together on the same branch. This call is used for communication when male and female are far from one another and before starting a duet (Sandoval et al. 2016). It is also studied that males can produce a solo song. These songs are normally comprised of three sections: “(1) songs began with high frequency elements similar to chip calls; (2) the middle section of songs contained frequency-modulated elements; and (3) songs concluded with a short trill” (Sandoval et al. 2016). Then the two will produce a loud “tsip” duet that decreases in frequency along a span of roughly five seconds. Individuals will then continue to survey the territory for up to 7 minutes and may produce the song a few more times. The song of Melozone leucotis has also been documented to be a communication device between male and females for foraging. If the male locates food while foraging away from the female he will sing his song to notify her and the juveniles (Sandoval & Mennill 2012). White-eared ground-sparrow males showed a high level in individual song distinctness in a study by Sandoval et al (2014). This study also displayed that at least some males that share territory boundaries would have high similarity in repertoire (Sandoval et al. 2014). This is important for explaining how male white-eared ground-sparrows can use repertoire and fine scale acoustic structure to differentiate between other males in the surrounding area. This species has been documented in the field to forage mainly on the forest floor. White-eared ground-sparrows have been observed to preform a “kicking-up” motion in which they stir up the leaf litter in order to locate potential insects and fruits in the litter. M. leucotis has been documented to feed chicks moths, fruits of Ficus sp., fruits of Melastomataceae, and Acnistus arborecens (Sandoval & Mennill 2012). These birds frequently hop when they are moving through the thickets to forage. These birds have also been documented to follow army ants. Three observations have been documented of M. leucotis foraging around army ants. M. leucotis is generally a insectivorous bird so this foraging style is fairly understandable (Vallely 2001).
Nest parasitism has been documented in white-eared ground-sparrows. Nests have been parasitized by Bronzed Cowbirds (Molothrus aenneus). Two nests were demonstrated to be multiply parasitized by the cowbirds, containing 6 - 7 parasitic eggs (Sandoval & Mennill 2012). It was stated that the reproductive success for the sparrows that had been parasitized was low. This may be because of a decrease in ability to incubate the original sparrow eggs with many cowbird eggs. It has also been documented that parental ground-sparrows have been seen to feed fledging cowbird chicks that were parasitized. The parasitism rate in the White-eared ground-sparrow population in Costa Rica was high, 50%, containing eggs or chicks of cowbirds (Sandoval & Mennill 2012). It has been predicted that the parasitism by Bronzed Cowbirds on M. leucotis will have negative affects for populations and reproductive success in the species where nest are highly parasitized.
The white-eared ground sparrow (Melozone leucotis) is a large American sparrow which occurs locally in Middle America, mostly in foothills, from southern Mexico and Guatemala to northern Costa Rica.
This bird is found typically at altitudes between 500 and 2,000 m (1,600 and 6,600 ft) in the undergrowth and thickets of ravines, forest edge, and other semi-open woodland including second growth and large gardens. The nest, built by the female, is a massive bowl of stems, twigs and other plant material constructed on the ground or less than 75 cm (2.46 ft) up, and hidden amongst banana plants, orchids or similar cover. The female lays two brown-blotched white eggs, which she incubates for 12–14 days. The male helps in feeding the chicks.
The white-eared ground sparrow is on average 17.5 cm (6.9 in) long and weighs 43 g (1.5 oz). The adult has a stubby dark-grey bill and unstreaked olive-brown upperparts. The head is mainly black with a broken white eye ring and white patches in front of and behind the eye. The nape is green and the sides of the neck are bright yellow. The throat and breast patch are black, separated by a thin rufous-grey line, and the rest of the underparts are mainly white with grey on the flanks. Young birds have yellower underparts, and a duller indistinct head pattern.
North Nicaragua birds, M. l. nigrior, have a much broader black breast spot than the nominate Costa Rican form, and the northernmost of the three subspecies, M. l. occipitalis, has a grey crown stripe, obvious yellow supercilium, and very small breast spot.
White-eared ground sparrow calls include a thin tsip. The male's song is an explosive whistled spit-CHUR see-see-see.
The white-eared ground sparrow feeds on the ground on seeds, fallen berries, insects and spiders. It is usually in pairs, and is a shy species best seen at near or dusk, although easier to find than its skulking relative, Prevost's ground sparrow.
The white-eared ground sparrow (Melozone leucotis) is a large American sparrow which occurs locally in Middle America, mostly in foothills, from southern Mexico and Guatemala to northern Costa Rica.
This bird is found typically at altitudes between 500 and 2,000 m (1,600 and 6,600 ft) in the undergrowth and thickets of ravines, forest edge, and other semi-open woodland including second growth and large gardens. The nest, built by the female, is a massive bowl of stems, twigs and other plant material constructed on the ground or less than 75 cm (2.46 ft) up, and hidden amongst banana plants, orchids or similar cover. The female lays two brown-blotched white eggs, which she incubates for 12–14 days. The male helps in feeding the chicks.
The white-eared ground sparrow is on average 17.5 cm (6.9 in) long and weighs 43 g (1.5 oz). The adult has a stubby dark-grey bill and unstreaked olive-brown upperparts. The head is mainly black with a broken white eye ring and white patches in front of and behind the eye. The nape is green and the sides of the neck are bright yellow. The throat and breast patch are black, separated by a thin rufous-grey line, and the rest of the underparts are mainly white with grey on the flanks. Young birds have yellower underparts, and a duller indistinct head pattern.
North Nicaragua birds, M. l. nigrior, have a much broader black breast spot than the nominate Costa Rican form, and the northernmost of the three subspecies, M. l. occipitalis, has a grey crown stripe, obvious yellow supercilium, and very small breast spot.
White-eared ground sparrow calls include a thin tsip. The male's song is an explosive whistled spit-CHUR see-see-see.
The white-eared ground sparrow feeds on the ground on seeds, fallen berries, insects and spiders. It is usually in pairs, and is a shy species best seen at near or dusk, although easier to find than its skulking relative, Prevost's ground sparrow.
