Capped heron

Capped heron
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Pelecaniformes
Family: Ardeidae
Genus: Pilherodius
L. Reichenbach, 1853
Species: P. pileatus
Binomial name
Pilherodius pileatus
(Boddaert, 1783)
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The Capped Heron (Pilherodius pileatus) is a bird of the order pelacaniforme and the family Ardeidae.[2] It is endemic of the neotropic and inhabits the amazonin rainforest from the center of Panama to the south of Brazil.[3] It is the only species of the Phaenthon genera and one of the least known of the Ardeidae family. It is superficially similar to the group of the night herons, but this one is active during daytime or in the crepuscular.[4]

Description

This species is very distinct from the other herons because of being the only one with a blue peak and face, and a black crown. The belly, the chest and the neck are covered with yellowish-white or light-cream feathers. The wings and the back are covered with white feathers. Three to four white long feathers extend from the black crown.[3][5][6][7] It has not been registered a sexual dimorphism in the color or brightness.[8] The body length of an adult varies between 510 and 590 mm, the wing chords between 263 and 280 mm, the tail between 95 and 103 mm, and the tarsus between 92 and 99 mm.[5] The weight of and adult varies between 444 and 632 g.[9] The juveniles are very similar to the adults. They only differ in body length and the white feathers are slightly grey.[3]

Phylogeny

There is little known about the relationship of P. pileatus with the other species of the family Ardeidae, because of its exclusion in the genetic studies.[10][11][12] With the few information available it is believed that the closest living species is the whistling heron (Syrigma sibilatrix).[4]

Distribution

It is an endemic of the neotropic and almost exclusive of the amazonian rainforest.[13] It is present in Bolivia, Brazil, Colombia, Ecuador, French Guiana, Panama, Paraguay, Peru, Suriname and Venezuela.[2] Habita en tierras bajas hasta los 900 m.[13] In Venezuela it is only found until the 500 m,[14] and in Ecuador until the 400 m.[15] Although there are no migrations registered to this species and it is believed that is a sedentary, there may be seasonal move in Darien, Panama.[8][16]

Habitat

The capped heron normally inhabit swamps and ditches in wet grasslands or rainforests. In some occasions it can venture into deeper ponds and rivers. Prefer to forage in the shore or in the floating vegetation.[17] They have also been observed in trenches of coffee plantations and flooded rice fields.[18]

Feeding

Capped Heron hunt mainly for fish, but also aquatic insects and larva, tadpoles and frogs.[8] Fish tend to be between 1 and 5 cm long. The insects are hunted in the nearby vegetation along the river or pond, and the fishes in the shallow waters. In a typical hunting sequence the heron will stand erectly searching for a potential prey. When locating the prey they will crouch slowly and extend their neck. Finally they will introduce their beak in the water at a great speed to catch the prey. The frequency of success observed is 23%. They can also use the same sequence while walking in the shallows. They usually walk slowly covering the same area repeatedly pausing for a few seconds while slowly moving a foot to take a new step.[17] There are reports of individuals doing aerial hunting,[9] peaking, gleaning, foot paddling, dipping, swimming feeding, bill-vibrating.[17] Capped Herons move frequently between feeding sites, sometimes flying up to 100m. May be crepuscular,[3] but have been observed foraging during broad daylight, unlike the night-herons.[19] They usually hunt in solitary.[20]

Behaviour

Territoriality

Strongly territorial, so much so that the same bird may be seen at the same foraging site for weeks at a time.[21] One Capped Heron was seen chasing another away from a foraging site, until the other bird settled high in a tree.[19]

Interespecific and intraespecific behaviour

The capped heron is normally found in solitary, although there are cases that they can be found in couples or in groups till fourn individuals.[20] The capped heron is normally found in solitary, although there are cases that they can be found in couples or in groups till fourn individuals. Birds may be seen with other species such as Snowy Egrets (Egretta thula) and Scarlet Ibis (Eudocimus ruber), however other studies have found that they avoid large mixed-species flocks, appearing in fewer than 1% of 145 observed feeding aggregations.[17][20] Capped Herons appear to be submissive to Great Egrets (Ardea alba), but dominant to Snowy Egrets (Egretta thula) and Striated Herons (Butorides striatus).[17]

Reproduction

There is very little known about the reproduction of this species.[5][16][16] Captive breeding in Miami, USA indicates that a female may lay 2-4 dull white eggs, incubation lasts 26–27 days, and that the chick has white down.[22] However, these captive individuals failed to have any young survive, possibly due to a deficient diet or abnormal behavior in the adults. Based on birds with a similar biology, it's likely that they maintain family groups and care for young after fledging. There may be a two cycle breeding pattern, with northern and southern populations breeding at different times of the year.[7]

Conservation

This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend is not known, but the population is not believed to be decreasing sufficiently rapidly to approach the thresholds under the population trend criterion (>30% decline over ten years or three generations). The population size has not been quantified, but it is not believed to approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.[2] Nevertheless, this species occurs in very low densities and it is considered as “rare” in Ecuador, Colombia, Venezuela and Panama.[3][14][15][23]

It seems there are no great threats for capped heron since it appears to be adaptable and may be expanding its use of man made habitats.[7] People have found some individuals in pools along the Transamazonian Highway Brasil.[24] However, given that it is mainly a riverine forest species, the loss of this habitat due to logging and the conversion of forest to pasture, might pose long term threats.[8]

References

  1. ↑ BirdLife International (2012). "Pilherodius pileatus". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013.
  2. 1 2 3 BirdLife International 2009. Pilherodius pileatus In: 2010 IUCN Red List of Threatened Species
  3. 1 2 3 4 5 Ridgely, R. S., & Gwynne, J. A. (1989). A guide to the birds of Panama: with Costa Rica, Nicaragua, and Honduras. Princeton University Press.
  4. 1 2 Payne, R. B., & Risley, C. J. (1976). Systematics and evolutionary relationships among the herons (Ardeidae). Museum of Zoology, University of Michigan.
  5. 1 2 3 Wetmore, A., Pasquier, R. F., & Olson, S. L. (1965). The Birds of the Republic of Panama: Tinamidae (tinamous) to Rynchopidae (skimmers) (Vol. 1). Smithsonian Institution.
  6. ↑ Blake, E. R. (1977). Manual of Neotropical birds (Vol. 1). University of Chicago Press.
  7. 1 2 3 Hancock, J., Elliott, H. F., Hayman, P., & Gillmor, R. (1978). Herons of the world. London Editions.
  8. 1 2 3 4 Kushlan, J. A., & Hancock, J. A. (2005). Herons. OUP Oxford.
  9. 1 2 Willard, D. E. (1985). Comparative feeding ecology of twenty-two tropical piscivores. Ornithological Monographs, 788-797.
  10. ↑ Sheldon, F. H., Jones, C. E., & McCracken, K. G. (2000). Relative patterns and rates of evolution in heron nuclear and mitochondrial DNA. Molecular Biology and Evolution, 17(3), 437-450.
  11. ↑ Sheldon, F. H., & Slikas, B. (1997). Advances in ciconiiform systematics 1976-1996. Colonial Waterbirds, 106-114.
  12. ↑ Sheldon, F. H. (1987). Phylogeny of herons estimated from DNA-DNA hybridization data. The Auk, 97-108.
  13. 1 2 Stotz, D. F., Fitzpatrick, J. W., Parker III, T. A., Moskovits, D. K., & Snow, D. (1996). Neotropical birds: ecology and conservation (No. 598.298 N438). Chicago: University of Chicago Press.
  14. 1 2 Hilty, S. L. (2002). Birds of Venezuela. Princeton University Press.
  15. 1 2 Ridgely, R. S., & Greenfield, P. J. (2001). The birds of Ecuador: status, distribution, and taxonomy (Vol. 1). Cornell University Press.
  16. 1 2 3 Hancock, J., & Kushlan, J. A. (2010). The herons handbook. A&C Black.
  17. 1 2 3 4 5 Kushlan, J. A., Hancock, J. A., Pinowski, J., & Pinowska, B. (1982). Behavior of Whistling and Capped Herons in the seasonal savannas of Venezuela and Argentina. Condor, 255-260.
  18. ↑ Haverschmidt, F. (1952). More bird weights from Surinam. The Wilson Bulletin, 234-241.
  19. 1 2 Haverschmidt, F. (1958). The feeding habits of the Capped Heron (Pilherodius pileatus). The Auk, 75(2), 214-214.
  20. 1 2 3 Ogden, J. C., & Thomas, B. T. (1985). A colonial wading bird survey in the Central Llanos of Venezuela. Colonial Waterbirds, 23-31.
  21. ↑ Heckman, C. W. (2013). The Pantanal of Poconé: biota and ecology in the northern section of the world’s largest pristine wetland (Vol. 77). Springer Science & Business Media.
  22. ↑ Martinez-Vilalta, A., & Motis, A. (1992). Family Ardeidae (Herons). Handbook of the Birds of the World, 1, 376-429.
  23. ↑ Hilty, S. L., & Brown, B. (1986). A guide to the birds of Colombia. Princeton University Press.
  24. ↑ Sick, H. (1993). Birds in Brazil. Princeton Univ. Press, Princeton, New Jersey.
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