And another occasional bird: Swainson’s Flycatcher.
And a new bird species: Turkey Vulture

Black-backed Grosbeak Pheucticus aureoventris

Rasmus is Danish and visited Costanera in November. He sent us this male of Black-backed Grosbeak, an unusual species for Buenos Aires. Far from its area of distribution this individual of grosbeak is supposed to have escaped or to have been released. The previous record dates back to 2007. Rasmus took some other photographs which can be seen on his blog. Enjoy them. © Rasmus Due Nielsen

Striped Owl Asio clamator

© Claudia y Tito Di Mauro

Rufous-sided Crake Laterallus melanophaius

Also with grown up chicks, which we could not photographed. © Claudia y Tito Di Mauro

New birds species: Turkey Vulture Cathartes aura

This vulture initiates the Cathartidae family © Gonzalo Díaz

Swainson’s Flycatcher Myiarchus swainsoni

Seen on Viamonte Canal © Daniel Vago

Chotoy Spinetail Schoeniophylax phryganophilus

© Pablo Mosto

First photographed case of parasitism of this season Shiny Cowbird-Black-and-rufous Warbling-Finch Molothrus bonariensis-Poospiza nigrorufa
© C y T Di Mauro	© C y T Di Mauro
© C y T Di Mauro	© C y T Di Mauro
© C y T Di Mauro	© C y T Di Mauro
© C y T Di Mauro	© C y T Di Mauro
First photographed victim of the 2012-2013 season

Rufescent Tiger-Heron Tigrisoma lineatum

For the third year in a row we can see chicks of Rufescent Tiger-Heron. © J. Simón Tagtachian

Hooded Siskin Carduelis magellanica

A fledgeling © Milano-Muszkats

Mockingbird and Emerald Mimus saturninus – Chlorostilbon aureoventris

Milano-Muszkats

Checkered Woodpecker Veniliornis mixtus

A juvenile already out of the nest © Dolores Fernández

Masked Yellowthroat Geothlypis aequinoctialis

Male © J Simón Tagtachian

Rufescent Tiger-Heron Tigrisoma lineatum

© J. Simón Tagtachian

Camuatí Wasp Polybia scutellaris

The Viamonte nest which was built last year. This year a new layer was added. © Cora Rimoldi

Dark-billed cuckoo Coccyzus melacoryphus

Amelia and Pablo tell us that they were watching this Dark-billed Cuckoo feed for a long time. It moved about the tree, jumping form one branch to the other in search for the spittle masses, caught the bug and ate it. Last November I wrote something on the biology of the spittlebug (See Rosewood). In this opportunity it is a link in the food chain, being predated by this cuckoo. What surprises me most is how malleable the spittle is that it kneads into a spaghetti-like string and keeps sticky without breaking. Photos © Amelia Besana

Black-and-white Tegu Lizard Tupinambis merianae © Amelia Besana

These three videos show the previous moments to and the mating. Some interesting displays could be associated with courtship. To cover the female with the body. To march without moving. The female moving in a circle before mating. To mate the male holds the female by the neck and positions her to penetrate her vent with his hemipenes. These are not external organs. They are everted for defecation and copulation and then they retract into the base of the tail. CR

Wren House Troglodytes aedon
© Amelia Besana	© Amelia Besana
Diligent parents, hungry offspring

Checkered Woodpecker Veniliornis mixtus

The same Checkered Woodpecker of last November. Male (with red nape) and female going in and out of the nest and doing the cleaning. © Claudia y Tito Di Mauro

White-barred Piculet Picumnus cirratus

Hembra © Pablo Mosto

Spot-winged Pigeon Columba maculosa

© J Simón Tagtachian

White-winged Becard Pachyramphus polychopterus

Male © Pablo Mosto

Southern Screamer Chauna torquata

© Dolores Fernández

Black-crowned Night-Heron Butorides striatus

© J Simón Tagtachian

Black-necked Swan Cygnus melacoryphus

© C y T Di Mauro

Yellow-billed Cardinal Paroaria capitata

© Pablo Mosto

]]> http://www.reservacostanera.com.ar/en/2012/12/02/novedades-diciembre-2012/feed/ 0 http://www.reservacostanera.com.ar/en/2012/11/05/novedades-noviembre-2012/ http://www.reservacostanera.com.ar/en/2012/11/05/novedades-noviembre-2012/#comments Mon, 05 Nov 2012 02:06:58 +0000 cora.rimoldi http://www.reservacostanera.com.ar/?p=14462 Tawny-crowned Pygmy-Tyrant
Euscarthmus meloryphus © C y T Di Mauro

Green-backed Woodpecker Colaptes melanochloros

Male and female © Milano-Muszkats

Guira Cuckoo Guira guira
I’m off to the Viamonte Grill! © C y T Di Mauro	What a tasty morsel I’ve got! © C y T Di Mauro
It seems sweetbread © C y T Di Mauro	or is it thin skirt? © C y T Di Mauro

Spectacled Tyrant Hymenops perspicillatus

Male © Milano-Muzskats

Spectacled Tyrant Hymenops perspicillatus

Female © Milano-Muszkats

Glittering-bellied Emerald Chlorostilbon aureoventris

© C y T Di Mauro

Hornero Furnarius rufus
© C y T Di Mauro	© C y T Di Mauro
© C y T Di Mauro	© C y T Di Mauro
© C y T Di Mauro	© C y T Di Mauro
This Hornero built the nest before getting to the antenna towards the Middle Path, Flew to and from the nest many times carrying food for the chicks

Checkered Woodpecker Veniliornis mixtus
The nest © C y T Di Mauro	The owner of the nest © C y T Di Mauro
With food for the chicks © C y T Di Mauro	Going into the nest © C y T Di Mauro
The chick can barely be seen © C y T Di Mauro	© C y T Di Mauro
Almost inside © C y T Di Mauro	Going out again © C y T Di Mauro
With another piece © C y T Di Mauro	To fetch some more © C y T Di Mauro

Rufous-sided Crake Laterallus melanophaius
© C y T Di Mauro	© C y T Di Mauro
We saw the chicks but could not photograph them because it quickly hid them. They are in the Gull Pond, on the Lizard Path approximately 200 metres away from the Middle Path. CyT See L10 on map

Tropical Kingbird Tyrannus melancholicus

© J Simón Tagtachian

Brown-chested Martin Progne tapera

© J Simón Tagtachian

Glittering-bellied Emerald Chlorostilbon aureoventris

Male © J Simón Tagtachian

Sooty-fronted Spinetail Synallaxis frontalis

© J Simón Tagtachian

Warbling Doradito Pseudocolopteryx flaviventris

© Pablo Mosto

Dark-billed Cuckoo Coccyzus melacoryphus

© Pablo Mosto

Benteveo rayado Myiodynastes maculatus

© Carlos Gonzalez Ledo The Streaked Flycatcher is a migrant bird which nests in costanera. Every year they fly back and forth from northern South America to Argentina. It breeds here and goes back north to spend the austral winter. Out of the seven recognized subspecies of Streaked Flycatcher, Myiodynastes maculatus solitarius is the one that migrates to Argentina. Year after year we can count on this flycatcher. They stay from October to March approximately. As they arrive they have to establish their territory. They make a lot of fuss when they chase each other with rapid flights manouvering among trees and singing loudly. It is difficult to follow the scene since they get out of sight easily. They also compete against other species for holes in trees, like those of woodpeckers’, where they will nest. CR

It rains under the rosewoods (Tipuana tipu) When November comes and rosewoods become green again an unusual phenomenon is witnessed for only a couple of weeks – it rains under the rosewoods no matter if it is a sunny or cloudy day. This is caused by an insect, the spittlebug, whose nymph feeds on this tree’s sap. The nymph produces a spittle mass around the stalks which is a good cover against predators and keeps it moist. The foam is the waste product eliminated after sap nutrients have been absorbed, into which air bubbles are introduced through a breathing tube which is at the end of the abdomen of the nymph.
© Carlos Gonzlez Ledo Nymphs are under the foam	© Roberto Ares I came across it when I enlarged the photo © Roberto Ares
When the spittle masses become too heave they disintegrate into drops. This is known as “the weeping of the rosewoods”. If dripping is intense puddles are formed on the ground.
© Roberto Ares	© Cora Rimoldi
This phenomenon may be experienced under the rosewoods planted on the streets. But this phenomenon may well pass unnoticed since “the weeding of the rosewoods” is confused with “the weeping of the balconies”.

Two exotics Man has always moved with his culture on his back throughout history. For whatever reason: cultural nostalgia, economic reasons, deliberately or accidentally the introduction of plant and animals has caused in the receiving environment an unequal struggle. The exotics have no their natural predators which control the spread of the population to such an extent that they grow out of control and become pests. This caused the regression of the autoctonous flora and fauna and became a call to attention, which has lead the Government to legislate on the protection and conservation of native flora and fauna. Nevertheless, fulfilment of the law is still not a priority. In this photo two introduced species: the European Starling Sturnus vulgaris with a fruit of the Mulberry Tree Morus nigra in its bill. This tree is native to Eurasia. Its fruit is fleshy and purple and is highly appreciated by birds which disseminate the seeds. In the reserve this tree has easily spread. The first records of the European Starling in Buenos Aires date back to the late ’80. According to investigations it has expanded along the coast of the Province of Buenos Aires till Mar del Tuyú. At Costanera this is a resident bird and its presence was first recorded in 1997 as Germán Pugnali points out. It is very aggressive: it pushes native birds or migratory birds in their competence for food and nests. It is opportunistic: it makes do with anything it can get. It has a high rate of reproduction: it would almost double their population yearly. The negative impact this bird caused at an economic an ecological level in other countries where it was also introduced have been broadly investigated. We must learn from this to avoid this situation. Population growth is so fast that it becomes imperative to take measures to erradicate this species before it is too late. CR

New bird species: White-throated Hummingbird Leucochloris albicollis

See more photos © J. Simón Tagtachian

Brazilian Duck Amazonetta brasiliensis
Female © J. Simón Tagtachian	Pair © J. Simón Tagtachian

Black-and-rufous Warbling-Finch Poospiza nigrorufaJuvenile © Carlos Gonzalez Ledo

Speckled Teal Anas flavirostrisAn there was another pair nearby © Carlos Gonzalez Ledo

Bran-colored Flycatcher Myiophobus fasciatus© Carlos Gonzalez Ledo

Goblet flower Cypella herbertii© Carlos Gonzalez Ledo

Visit to the Raptor Rehabilitation Center

Crowned Eagle Harpyhaliaetus coronatus © Carlos Gonzalez Ledo

Ringed juvenile Roadside Hawk Buteo magnirostris © Jesús Fernández

Learn the activities of this center. Read interview with Andrés Capdevielle who is in charge of the Raptor Rehabilitation Center in the reserve

Masked Gnatcatcher Polioptila dumicolaEvery year we can find them nesting. The male is incubating. © Claudia y Tito Di Mauro

Small-billed Elaenia Elaenia parvirostris© Claudia y Tito Di Mauro

Red-eyed Vireo Vireo olivaceous© Claudia y Tito Di Mauro

Hornero Furnarius rufusVery badly hurt on the head but alive and kicking © Claudia y Tito Di Mauro

Bay-winged Cowbird Agelaioides badiusWelcoming visitors © Claudia y Tito Di Mauro

Rufous-collared Sparrow Zonotrichia capensis© Claudia y Tito Di Mauro

White-winged Becard Pachyramphus polychopterus It seems this male doesn’t like juicy mullberries. It crushes one after the other against the branch forcing juice out. © J Simón Tagtachian

European Starling Sturnus vulgarisA white starling has been in the reserve for several years now. Will it be the same? © J Simón Tagtachian

Monk Parakeet Myiopsitta monachus© J Simón Tagtachian

]]> http://www.reservacostanera.com.ar/en/2012/11/05/novedades-noviembre-2012/feed/ 0 http://www.reservacostanera.com.ar/en/2012/10/07/novedades-octubre-2012/ http://www.reservacostanera.com.ar/en/2012/10/07/novedades-octubre-2012/#comments Sun, 07 Oct 2012 23:14:01 +0000 cora.rimoldi http://www.reservacostanera.com.ar/?p=14148 Picture of all birds of October 2012 Unicolored Blackbird F Unicolored Blackbird M House Wren Speckled Teal Guira cuckoo Yellow-winged Blackbird F Rufous-bellied Thrush Ferruginous Pygmy-Owl Monk Parakeet Chestnut-capped Blackbird M Great Kiskadee Bran-colored Flycatcher Great Egret Rufous-collared Sparrow Small-billed Elaenia Chalk-browed Mockingbird White-crested Tyrannulet Picazuro Pigeon Rufescent Tiger-Heron Creamy-bellied Thrush Southern-crested Caracara Roadside Hawk Masked Gnatcatcher F Glittering-bellied Emerald F Masked Gnatcatcher M Hooded Siskin M Sayaca Tanager Saffron YellowFinch M Rufous Hornero Checkered Woodpecker F Hepatic Tanager M House Sparrow M European Starling Hooded Siskin F Sooty-fronted Spinetail Cocoi Heron Bay-winged Cowbird Green-barred Woodpecker F Golden-crowned Warbler Gilded Sapphire Epaulet Oriole Tropical Kingbird Vermilion Flycatcher M Brown-chested Martin Black-and-rufous Warbling-Finch Screaming Cowbird Shiny Cowbird M Shiny Cowbird F Eared Dove Pied Water-Tyrant Narrow-billed Woodcreeper Red-eyed Vireo Freckle-breasted Thornbird Yellow-browed Tyrant White-rumped Swallow Snowy Egret American Kestrel M Long-winged Harrier Harris's Hawk Yellow-winged Blackbird M Blue-and-yellow Tanager M Bare-faced Ibis Wattled Jacana Black-hooded Parakeet Green-winged Saltator Black-capped Warbling- Finch Neotropic Cormorant White-lined Tanager M Glittering-bellied Emerald M Spectacled Tyrant F Saffron YellowFinch F Golden-billed Saltator Tawny-crowned Pygmy-Tyrant Yellow-billed Cardinal Streaked Flycatcher Double-collared Seedeater M Campo Troupial Dark-billed Cuckoo Tropical Parula Fork-tailed Flycatcher Solitary Black Cacique Checkered Woodpecker M Great Pampa-Finch Maked Yellowthroat M Red-crested Cardinal Chimango Caracara

Rufous-collared SparrowChingolo Zonotrichia capensis© J. Simón Tagtachian

Checkered Woodpecker Veniliornis mixtusA woodpecker building a nest in a natural hole of a tree. Its bill is dirty with chips © Milano-Muszkats

Chalk-browed Mockingbird and Tegu Lizard Mimus saturninus – Tupinambis merianae
© Milano-Muszkats	© Milano-Muszkats
Near the water tank at the Viamonte entrance we saw a tegu lizard and two mockingbirds, which kept harrassing and pecking the tail of the lizard. We don’t know why. Afterwards the lizard sneaked away. © Milano-Muszkats

Tawny-crowned Pygmy-Tryant Euscarthmus meloryphusThere were two individuals: only one of them had the crest erect. But on both the orange crest was visible. See more photos © J. Simón Tagtachian

Dark-billed Cuckoo Coccyzus melacoryphus© Pablo Serur

Streaked Flycatcher Myiodinastes maculatus© Pablo Serur

Fork-tailed Flycatcher Tyranus savanna© J. Simón Tagtachian

Campo Troupial Icterus jamacaii© Pablo Serur

Tropical Parula Parula pitiayumi© Pablo Serur

Glittering-bellied Emerald Chlorostilbon aureoventrisMacho © Carlos Gonzalez Ledo

Urutu Pit Viper Bothrops alternatus© Carlos Gonzalez Ledo

Tawny-crowned Pygmy-Tyrant Euscarthmus meloryphusSeen on the path leading from the triangle to the canal, about 50 meters before reaching it. (See H 18 on sector map) © Claudia y Tito Di Mauro

Monk Parakeet Myiopsitta monachusThis Parakeet not only holds the fruit with its foot but also takes it to its mouth © Carlos Gonzalez Ledo

Four waterbirds

Rufous-bellied Thrush Turdus rufiventrisAnother featherless-tailed bird. See Fright or shock molt © Claudia y Tito Di Mauro

Cocoi Heron Ardea cocoiPlacing the prey headfirst © J Simón Tagtachian

Screaming Cowbird Molothrus rufoaxillaris© J. Simón Tagtachian

Red-eyed Vireo Vireo olivaceus© Claudia y Tito Di Mauro

Great Kiskadee Pitangus sulphuratusTwo trips with a piece of bread each to feed the chicks? © Claudia y Tito Di Mauro

Vermilion Flycatcher Pyrocephalus rubinusJuvenile © J Simón Tagtachian

Freckle-breasted Thornbird Phacellodomus striaticollis© Claudia y Tito Di Mauro

White-rumped Swallow Tachycineta leucorrhoa© J Simón Tagtachian

American Kestrel Falco sparveriusAdult (right) and juvenile © J Simón Tagtachian

Rufous Hornero Furnarius rufusBuilding their love nest © Carlos Gonzalez Ledo

Green-winged Saltator Saltator similis© J. Simón Tagtachian

Pied Water-Tyrant Fluvicola pica

Seen at Viamonte Canal © Pablo Serur

Two new plant species
Lavander trumpet vine Bignonia callistegioides	Blue Heliotrope Monteiroa glomerata
Replacing exotic with native species is a task systematically being carried out at the reserve. Along the paths stakes may be seen with young plants tied to them. These are raised from seeds or cuttings in the nursery. When time comes they are planted either by the personnel or those who join planting activities open to public. The blue heliotrope and the lavander trumpet vine were brought to be introduced into the reserve. These are native plants which were part of the flora of this area and in this way it may be recovered.

Bran-colored Flycatcher Myiophobus fasciatus

© C. y D. Bastías

Unicolored Blackbird Agelasticus cyanopus

© J. Simón Tagtachian

Ferruginous Pygmy-Owl Glaucidium brasilianum

With a rat. Can you see the tail? © J. Simón Tagtachian

]]> http://www.reservacostanera.com.ar/en/2012/10/07/novedades-octubre-2012/feed/ 0 http://www.reservacostanera.com.ar/en/2012/09/09/novedades-setiembre-2010-2/ http://www.reservacostanera.com.ar/en/2012/09/09/novedades-setiembre-2010-2/#comments Sun, 09 Sep 2012 02:24:58 +0000 cora.rimoldi http://www.reservacostanera.com.ar/?p=13860 Rose-billed Pochard
Netta peposaca © J. Simón Tagtachian

Long-tailed Reed-Finch Donacospiza albifrons

© J. Simón Tagtachian

Rusty-collared Seedeater Sporophila collaris

Female © J. Simón Tagtachian

Striped Owl Asio clamator

© Claudia y Diego Bastías

Spot-winged Pigeon Columba maculosa

© Claudia y Diego Bastías

Sharp-billed Canastero Asthenes pyrrholeuca

A very shy bird which quickly hides in the vegetation. Here the orange throat spot is seen. © Pablo Mosto

Masked Yellowthroat Geothlypis aequinoctialis

Male. Another summer visitor. © Pablo Serur

Vermilion Flycatcher Pyrocephalus rubinus

Male and a juvenile? © Carlos Gonzalez Ledo

Sharp-billed Canastero Asthenes pyrrholeuca

Rufous outer rectrices © Pablo Serur

Roseate Spoonbill Platalea ajaja

Flying past Brasil’s huts © J. Simón Tagtachian

New mammal species: South American Fur Seal Arctocephalus australis

On 9th of September three visitors (Federico, Manuel y Rodrigo) helped to rescue a South American Fur Seal pup which was on the coast. It was taken to the verterinary sector to be examined. They believed this calf had been lost for several days and far from its mother which nursed and taught the calf to catch fish. Unluckily it died a few hours later. The story (in Spanish)(Buscando refugio) of these three young men also teaches us we must be cautious in a situation like this. Good for them they sent for the personnel, but we must wait for them to act. But not all the cases of strayed calves end so dramatically. I invite you to read the report which Eduardo Haene has gently sent us (A South American Fur Seal calf appeared on the coast of Costanera Sur Ecological Reserve) 6-2012 © Eduardo Haene

Hooded Siskin Carduelis magellanica

© J. Simón Tagtachian

Blue-and-yellow Tanager Thraupis bonariensis
	Juvenile and male. © J. Simón Tagtachian

Scissor-tailed Nightjar Hydropsalis torquata

Male. An unvaluable photo, since this bird of nocturnal habits is rarely seen during the day. © Claudia y Diego Bastías

Solitary Cacique Procacicus solitarius

Just beginning to build the nest © Pablo Mosto

Scarlet-headed Blackbird Amblyramphus holosericeus

A photo taken at a far distance © Amelia Besana

Green-barred Woodpecker Colaptes melanochloros

Female entering nest © Pablo Mosto

White-rumped Swallow Tachycineta leucorrhoa

A couple of White-rumped Swallows were flying about. This swallow leant on the edge, introduced its head and rapidly flew off. Was it looking for a place to nest? It was carrying nothing in the bill © Pablo Mosto

Yellow-browed Tyrant Satrapa icterohprys

© Pablo Mosto

Brown-and-yellow Marshbird Pseudoleistes virescens

© Pablo Mosto

Rufescent Tiger-Heron Tigrisoma lineatum A pair that will set people talking
© J. Simón Tagtachian
We were looking forward to the Tiger-Heron’s nesting. Finally, they were seen fixing last year’s nest. To our surprise this year the pair is formed with an adult and an individual still in juvenal plumage.
© J. Simón Tagtachian	© J. Simón Tagtachian
© J. Simón Tagtachian	© J. Simón Tagtachian

Gilded Sapphire Hylaris chrysura

Hummingbirds have also shown up © J. Simón Tagtachian

Two martin species have arrived
Brown-chested Martin Progne tapera© J. Simón Tagtachian	Gray-breasted Martin Progne chalybea© J. Simón Tagtachian
Black-and-rufous Warbling-Finch Poospiza nigrorufa © Amelia Besana	Ultramarine Grosbeak Cyanocompsa brissoniiMale © Amelia Besana
Fawn-breasted Tanager Pipraeidea melanonota© J. Simón Tagtachian	Hepatic Tanager Piranga flavaMale © J. Simón Tagtachian

Side-necked Turtle Phrynops hilarii

© J. Simón Tagtachian

]]> http://www.reservacostanera.com.ar/en/2012/09/09/novedades-setiembre-2010-2/feed/ 0 http://www.reservacostanera.com.ar/en/2012/08/13/novedades-agosto-2012/ http://www.reservacostanera.com.ar/en/2012/08/13/novedades-agosto-2012/#comments Mon, 13 Aug 2012 01:09:55 +0000 cora.rimoldi http://www.reservacostanera.com.ar/?p=13572 Fawn-breasted Tanager
Pipraeidea melanonota © J. Simón Tagtachian

Freckle-breasted Thornbird Phacellodomus striaticollis © J. Simón Tagtachian

Ultramarine Grosbeak Cyanocompsa brissonii Male © Carlos Gonzalez Ledo

Great Grebe Podiceps major © J. Simón Tagtachian

Black-hooded Parakeet Nandayus nenday Eating the fruit of Melia azederach © Milano-Muszkats

Roadside Hawk Buteo magnirostris © J. Simón Tagtachian

Sooty-fronted Spinetail Synallaxis frontalis

© J. Simón Tagtachian A spinetail with a featherless tail It is strange to see a bird with a featherless tail. Generally one or two feathers may be missing when birds are molting but not all of them at the same time. This massive feather molt may occur as a response to the fact of being grabbed by the tail by a predator. The bird sacrifices its tail, but saves its life. It is believed that there must be a relaxation of the muscles holding the feather which causes its detachment. As the whole piece is lost, the feather grows back right away. This molt is known as shock molt or fright molt. This phenomenon has also been reported in cases with birds being handled and has been registered after catastrophic events. CR

New bird species: Suiriri Flycatcher Suiriri suiriri

© J. Simón Tagtachian

Vermilion Flycatcher Pyrocephalus rubinus

The males are arriving © J. Simón Tagtachian

Red-rumped Warbling-Finch Poospiza lateralis
© J. Simón Tagtachian	© J. Simón Tagtachian

Hepatic Tanager Piranga flava
Female © J. Simón Tagtachian	Female © J. Simón Tagtachian

Speckled Teal Anas flavirostris

How nice to see at least one family of ducks at Costanera! A scene so common not so long ago! © J. Simón Tagtachian

Water in the Coypu Pond

See more photos on www.siyc.com.ar/fotonaturaleza/historia/fotos.php?archivo=20120818.inc © J. Simón Tagtachian

Ferruginous Pygmy-Owl Glaucidium brasilianum
© J. Simón Tagtachian	© J. Simón Tagtachian
An atypical Ferruginous Pygmy-Owl with grey face (?)

Red-rumped Warbling-Finch Poospiza lateralis

© J. Simón Tagtachian

Snowy-crowned Tern Sterna trudeaui

© J. Simón Tagtachian

Limpkin Aramus guarauna

© J. Simón Tagtachian

Hooded Siskin Carduelis magellanica

A small flock. © J. Simón Tagtachian

Cattle Tyrant Machitornis rixosa© J. Simón Tagtachian	Shiny Cowbird Molothrus bonariensisFemale and male © J. Simón Tagtachian
White-tipped Dove Letotila verreauxi© J. Simón Tagtachian	Whistling Heron Syrigma sibilatrix© J. Simón Tagtachian
Speckled Teal Anas flavirostris© J. Simón Tagtachian	Red-fronted Coot Fulica rufifrons© J. Simón Tagtachian

Blue-billed Black-Tyrant Knipolegus cyanirostris

Female. Rectrices edged rufous © J. Simón Tagtachian

Green-winged Saltator Saltator similis
© J. Simón Tagtachian	© J. Simón Tagtachian
Same juvenile a week later

White-rumped Swallow Tachycineta leucorrhoa

Seen two weeks ago but photographed only yesterday. A small group of 5 individuals was flying around. The first to arrive. © Furman-Bastías

Brown-hooded Gull Chroicocephalus maculipennis

The breeding season comes and we note that birds are more active. They seem to wake up.There are chases, displays, increase in vocalizations, etc. and there are also changes in their appearance, many of which pass unnoticed to the untrained eye. But the nuptial or alternate plumage leaps to the eye. This gull’s nuptial or alternate plumage is a brown hood which covers its head, which is practically white in its basic (also called winter) plumage. These changes are due to the preparation of the reproductive system for a new breeding cycle. Environmental factors such as day length, light intensity, temperature, etc regulate the activity of the pituitary gland which segregates the hormones which stimulate these changes. Late in the reproductive season these hormones are inhibited by others which curb all this efervescence till the next cycle. © J. Simón Tagtachian

Striped Owl Asio clamator

© Milano-Muszkats

Campo Troupial Icterus jamacaii

© Milano-Muszkats

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