Now the California gull, Larus californicus

This is the California gull, Larus californicus (Lawrence, 1854). It is subs. californicus.

California gull Larus californicus Ad 1

California gull Larus californicus 3cy 7

California gull Larus californicus 3cy 1

Here we see the white mirrors in P9 and P10, which are characteristic, and the white trailing edge to inner wing. This (both photos of same individual) is an adult (at least 4cy) with the winter plumage (hindneck has dense brown streaks). These first three photos were taken at Wilder Ranch State Park, Santa Cruz, along the coast line.

California gull Larus californicus 062

California gull Larus californicus 3cy  California gull Larus californicus 3cy

A detail of the wonderful head of this gull (same individual in these two photos, an ad). Note the dark iris, and the color pattern in the bill ring (black with red-orange tinted patch in the lower mandible). The bill is characteristically 4-colored: yellowish at the base, black ring, red-orange dot and ivory tip- this separates it from Ring-billed and Herring. The leg color is also characteristic (green-bluish) but apparently is very variable. I saw other ad birds with very yellow legs. These two photos were taken in San Lorenzo Park, Santa Cruz, CA.

California gull Larus californicus 3cy

This is a 3cy bird, finishing molt to 3rd winter. The bill ring is wholly black; there are no white patches on P feathers, nor white mirrors. The bill is longer than in Ring-billed and the head is more massive. The photo was taken at Moss Landing, Elkhorn Slough, CA.

California gull Larus californicus 2cy 6

This is a 1cy bird (juvenile molting into 1st winter plumage), with characteristic black-tipped bill with pale pink in the base. It has not yet started te molt of the scapulars, yet some grayish ones seem to be apparent- the median coverts look worn and faded, creating pale midwing-panel; so the bird is a bit delayed in its molt.

EXIF data:

e_Model NIKON D7000
e_LensModel AF-S VR Zoom-Nikkor 70-300mm f/4.5-5.6G IF-ED
e_CameraSerialNumber 6074229
e_FlashExposureComp 0
e_ISOSpeedRating 100
e_ColorModel RGB
e_Depth 16
e_FocalLength 300
e_PixelHeight 3264
e_ApertureValue 5.6
e_WhiteBalance 1
e_ShutterSpeed 0.002
e_Flash 16
e_CaptureDayOfMonth 13
e_CaptureMonthOfYear 10
e_CaptureYear 2013

Heermann’s gull in my recent trip to California

These are some shots of my recent trip to California, last October, where I had the opportunity to do a whale watching trip offshore Monterrey Bay, from Moss Landing. I’ll be posting more photos soon…

Heermann’s (Larus heermanni (Cassin, 1852) is one of my favorite gulls, with a beautiful plain grey plumage in the adult, contrasting with the white patches and the coral-red bill, and a smooth dark brown plumage of the immature birds.  They were common birds along the coast up to Santa Cruz, quite often in large flocks. The population size is estimated in ca. 150000 pairs.

Heermann s gull Larus heermanni1

The adult birds here seem to be starting with the winter plumage, with paler grey heads.

Heermann s gull Larus heermanni 1cy 12

This is a  typical juvenile bird facing its 1st winter. The head is very dark grey, with a creamy base of the bill.

Heermann s gull Larus heermanni Ad 2

I like the broad white trailing edge of the wing. It’s a very elegant gull in flight (well, as all the gulls). I’m getting a gull-addicted, even for the commonest species, which pose very nice identification problems when you try to get to the details of the plumage patterns and molt. Even the most common species (i.e., the yellow-legged here in S Spain) pose amazing identification challenges, especially in winter.

Heermann s gull Larus heermanni 2cyw with Humpback whale

And here, with the Humpback whale…

The photos were taken with the Nikon D7000, AF-S VR Zoom-Nikkor 70-300mm f/4.5-5.6G IF-ED, f8, 1/1000, ISO 400.

Collared pratincoles

These are several shots of Collared pratincoles (Glareola pratincola, Glareolidae) that I took last weekend, at Marismas de Barbate, Cádiz. It was a very nice day, cloudy, but I was lucky to get close to the birds, creeping a lot. These birds are really beautiful. The geographic distribution is very patchy in the Western Palaearctic, with few areas in the Iberian Peninsula. 

DSC 3204

DSC 3063

DSC 3113

DSC 3214

Our study on functional extinction of frugivores, published in Science

Our new paper “Functional Extinction of Birds Drives Rapid Evolutionary Changes in Seed Size”, just published in this week issue of Science.

Mauro Galetti, Roger Guevara, Marina C. Côrtes, Rodrigo Fadini, Sandro Von Matter, Abraão B. Leite, Fábio Labecca, Thiago Ribeiro, Carolina S. Carvalho, Rosane G. Collevatti, Mathias M. Pires, Paulo R. Guimarães Jr., Pedro H. Brancalion, Milton C. Ribeiro, and Pedro Jordano. 2013. Functional Extinction of Birds Drives Rapid Evolutionary Changes in Seed Size. Science 340: 1086-1090.
DOI: 10.1126/science.1233774.

Palmito collage large

Photos, from top left, descending, to right:

1. Selenidera maculisrotris (male) handling a palmito seed.
2. Palmito fruits with beak marks, dropped beneath the palm, and regurgitated seeds.
3. Turdus flavipes trying to swallow a palmito fruit.
4. Ramphastos vitellinus (subsp. vitellinus) handling a fruit.
5. Selinedera maculirostris (male) picking a fruit.
6. Palmito seedling just after germination (note the seed still attached).
7. Palmito juçara, Euterpe edulis (Arecaceae).
8. Aburria (Pipile) jacutinga.
9. Baillonius (Pteroglossus) bailloni handling a fruit.
10. Turdus amaurochalinus (young), picking a fruit.
11. View of the ompbrphilous atlantic rainfrorest (Mata Atlántica) understory in Carlos Botelho park.
12. Penelope obscura.
13. Pyroderus scutatus, swallowing a fruit.
Photos by: Edson Endrigo, Pedro Jordano, Mauro Galetti, Marina Cortes, Guto Balieiro, and Lindolfo Souto.

The selective extinction of large frugivorous birds is associated with the rapid evolutionary reduction of seed size in a keystone palm.

Local extinctions have cascading effects on ecosystem functions, yet little is known about the potential for the rapid evolutionary change of species in human-modified scenarios. We show that the functional extinction of large-gape seed dispersers in the Brazilian Atlantic forest is associated with the consistent reduction of seed size of a keystone palm species. Among 22 palm populations, areas deprived of large avian frugivores for several decades present smaller seeds than non-defaunated forests, with negative consequences for palm regeneration. Coalescence and phenotypic selection models indicate that seed size reduction most likely occurred within the last 100 years, associated with human-driven fragmentation. The fast-paced defaunation of large vertebrates is most likely causing unprecedented changes in the evolutionary trajectories and community composition of tropical forests.

When we talk about biodiversity we normally refer to the number of species found in a given area. But these species have ecological functions that are essential to the functioning of ecosystems. The loss of a species also entails the loss of the ecological role it plays in the ecosystem, and this kind of extinction happens much unnoticed. We have documented the effect of functional extinction of large fruit-eating birds on an important plant trait – seed size – of a key plant species of the Atlantic Rainforest in Brazil, one of the biodiversity “hot-spots” on the planet. Our study is a natural experiment that takes advantage of the presence of fragmented areas of forest that have remained so since the early 1800s, when the development of crops such as coffee and sugar cane triggered the extensive deforestation of the Atlantic rainforest. Only 12% of the original forest persists, and over 80% of what remains are fragments are too small to maintain large animals. Our results show that the loss of large fruit-eating birds such as toucans leads to the size reduction of the seeds of a palm tree, which is a key species in these Atlantic forests. These evolutionary changes in fruit and seed size have occurred only in defaunated forests, where only small frugivorous birds persist. These small birds only successfully disperse smaller seeds.

PressReleaseImage 002

We studied 22 populations of this palm tree along the SE coast of Brazil. In the defaunated areas, which persist as fragments from several decades ago, the seed sizes are consistently smaller than in well-preserved forests, and this has negative consequences for regeneration. The smaller seed size in defaunated areas is not explained by other environmental or geographic variables. Fast natural selection: Small birds such as thrushes cannot swallow and disperse large seeds. Large birds, such as aracaris and toucans, play an important role in dispersing seeds of plants, especially of large seeds. In rainforests without toucans large seeds tend to disappear over time because undispersed seeds are attacked by seed predators. Small seeds are more vulnerable to desiccation and cannot withstand projected climate change.

We have combined a number of techniques including field work, genetic analyses, evolutionary models and statistical analyses. We collected ground data on a large number of palm trees in 22 populations, by collecting fruits, observing the avian frugivore assemblage and conducting germination experiments. We have also used DNA genetic markers to employ quantitative genetic models to estimate the intensity of selection on seed traits and coalescence theoretical models to infer the time of isolation of populations. Finally, we statistically analyzed the effect of different types of data, including climatic and environmental information, on seed size variation. 

Our work provides one of the few existing evidence that evolutionary change in natural populations can happen very fast as a direct result of changes induced by human action. The extinction of large vertebrates is happening all over the world and the implication is poorly known. These large bodied species maintain mutualistic interactions with plants: while flesh-fruited plants offer fruits as food sources, frugivores disperse their seeds. Such ecological process ensures natural regeneration of the forest. Unfortunately, the effect we document in our work is probably not an isolated case. The constant extirpation of large vertebrate in natural habitats is very likely causing unprecedented changes in evolutionary trajectories of many tropical species.

Habitat loss and species extinction is causing drastic changes in the composition and structure of ecosystems. This involves the loss of key ecosystem functions that can determine evolutionary changes much faster than we anticipated. Our work highlights the importance of identifying these key functions to quickly diagnose functional collapse of ecosystems.

Components of pollination effectiveness and their consequences in insular pollinator assemblages

Our paper “Quantity and quality components of effectiveness in insular pollinator assemblages” online in Oecologia. Thanks Cande and Alfredo. This is a field study of the pollination of Isoplexis canariensis by birds and lizards in the Canary Islands, a part of Cande Rodríguez PhD project.

Ecologically isolated habitats (e.g., oceanic islands) favor the appearance of small assemblages of pollinators, generally characterized by highly contrasted life modes (e.g., birds, lizards), and opportunistic nectar-feeding behavior. Different life modes should promote a low functional equivalence among pollinators, while opportunistic nectar feeding would lead to reduced and unpredictable pollination effectiveness (PE) compared to more specialized nectarivores.

857052 10200090196872009 1279714827 o

857170 10200090195551976 1653077443 o

859289 10200090199552076 2043863556 o

Dissecting the quantity (QNC) and quality (QLC) components of PE, we studied the opportunistic bird–lizard pollinator assemblage of Isoplexis canariensis from the Canary Islands to experimentally evaluate these potential characteristics. Birds and lizards showed different positions in the PE landscape, highlighting their low functional equivalence. Birds were more efficient than lizards due to higher visitation frequency (QNC). Adult lizards differed from juveniles in effecting a higher production of viable seeds (QLC). The disparate life modes of birds and lizards resulted in ample intra- and inter-specific PE variance. The main sources of PE variance were visitation frequency (both lizards and birds), number of flowers probed (lizards) and proportion of viable seeds resulting from a single visit (birds).

The non-coincident locations of birds and lizards on the PE landscape indicate potential constraints for effectiveness. Variations in pollinator abundance can result in major effectiveness shifts only if QLC is relatively high, while changes in QLC would increase PE substantially only at high QNC. The low functional equivalence of impoverished, highly contrasted pollinator assemblages may be an early diagnostic signal for pollinator extinction potentially driving the collapse of mutualistic services.

Muriquis

Muriquis (Brachyteles arachnoides) are the largest neotropical primates and the largest mammal endemic to Brazil, reaching more than 12 kg (Reis et al., 2006). They are endemic to the SE Brazil.

Previously recorded as different subspecies, muriquis are currently recognized as two distinct species, the northern muriqui B. hypoxanthus and southern muriqui B. arachnoides (Rylands et al., 1997). Aguirre (1971) estimated that before the arrival of Europeans there were about 400,000 muriquis in the Atlantic rainforest, distributed from southern Bahia to northern Paraná, and in 1971 there were no more than 3,000 individuals. Currently the northern muriqui occurs in southern Bahia, Espirito Santo and Minas Gerais and the southern muriqui occurs in southern Rio de Janeiro, São Paulo and northern Paraná (Melo and Dias 2005, Hirsch et al., 2006).

The muriquis live in groups of more than 30 individuals present social fission-fusion system where the group is divided into independent sub-groups of variable size. When in pristine areas they have a higher home ranges, ca. 1000ha, within daily displacements more than 5 km. I was fortunate enough to watch a group of 10-11 muriquis in Intervales, relatively close to the Carmo base. They were 3 males, 2-3 juveniles and 3 females, two of them carrying babies. Some of the individuals were feeding on the catkins of Cecropia glazeouvi. I approached them on a very steep slope and observed them for ca. 30 min. They were moving slowly among the canopies of the trees but with an extraordinary agility, always helping themselves with the tail. After a period close to me they moved quickly uphill.

Muriquis are herbivores, adapted to the handling, chewing and digestion of leaves or fleshy fruits, and they also consume flowers, seeds and bamboo (Strier 1991; Talebi et al., 2005). In relation to frugivory, muriquis have lower consumption of fruits (21% to 33%) in semi-deciduous Atalantic forest (Strier 1991, Martins 2006, 2008), but more intense consumption (35% to 71%) in ombrophilous Atlantic rain forests (Petroni 1993, 2000, Carvalho et al ., 2004; Talebi et al., 2005).

My friend Rafael Bueno did his master project (finished in 2010) on this species and tapirs [Frugivoria e efetividade de dispersão de sementes dos últimos grandes frugívoros da Mata Atlântica: a anta (Tapirus terrestris) e o muriqui (Brachyteles arachnoides)]. He did a great job showing the relevance of these frugivores for the dynamics of the Atlantic forest. Many tree species (at least 28 species) critically depend on their service for seed dispersal. Rafael recorded daily movements of muriqui groups ranging between 0.5 and 5.4 km. He estimated that on average, individual muriquis may disperse ca. 11,000 seeds/year. These amazing data show how relevant plant-animal mutualistic interactions are for the maintenance of tropical forests.