8/9/2019 agami_heron_report vikki thompson

1/4

Agami Heron (Agamia agami) Breeding Colony at

Cocococha Lake, Tambopata National Reserve, Peru.

Victoria Thompson

Abstract. This report describes a large breeding colony of Agami Herons (Agamia agamia), one of the

least known species of herons. Reports show that the species is known to breed in small colonies;

however, one exceptionally large colony of up to 900 nests is known to exist in French Guiana. With

over 123 nests, this appears to be one of the largest and most accessible colonies, providing much

scope for further study into this species. The report provides timings of key events over the breeding

season, and courtship behaviour, including beak duels and facial coloration are described, along with

predation of eggs by Brown Capuchin Monkeys (Cebus apella). Isolation and protection of breeding

sites are considered to be a factor in the suitability of a site to support large numbers for herons; due

to the importance of this colony in providing further insight into this species, every effort should be

made to ensure the site remains free from human disturbance. June 2007

______________________________________________

INTRODUCTION

The Agami heron is a small heron of up to

70cm, distinguishable by its long beak. Itoccurs in Central and South America. Due to

its rarity and secretive behaviour it is one of

the least known species of herons (Reynaud &Kushlan 2004). It is known to be a solitary

forager and to nest in small colonies, eitheralone or near to other species (Hancock &

Kushlan 1984). Scattered reports exist of a

number of small breeding colonies, and oneparticularly large colony in French Guiana,consisting of approximately 900 nests

(Reynaud & Kushlan 2004). This reportdescribes a large breeding colony at

Cocococha Lake, one of the largest oxbowlakes of the Tambopata National Reserve,

which is easily accessible by foot via a 5kmtrail from the Explorers Inn Lodge.

METHODS

The study was conducted over the period

December 2006 to April 2007. Observationswere made from a small catamaran, consistingof 2 metal canoes bolted together. The site

was only accessible by boat.Visits were made to the colony at various

times of the day and in various weatherconditions. No movement of birds to or from

the colony was seen between 7.30am or 6pm.As the majority of the herons were nesting

along the shore of the lake, and fairly visible,

an estimate of the population size wasproduced by counting the numbers of birds and

nests present during daylight hours. However,

it should be noted that the estimate is likely tobe an underestimate; although it was thought

that most birds were nesting along the lakeshore and fairly visible, some birds were

nesting along a small stream which leads from

the lake, and it is likely that other birds mayhave been nesting in denser vegetation further

into the forest.

The count was always made by the sameindividual, using 8x40 binoculars, from a

distance of approximately 25m. Any otherobservations such as, behaviour, predation and

development of chicks was documented. In

addition to field observations, information wassought from Elisban Armas, a local guide andlong-term resident of the area.

STUDY SITE

Cocococha Lake is situated in theTambopata National Reserve, a protected area

of 278,284ha in South-East Peru. The lake isaccessible via a 5km trail from Explorers Inn

lodge, a small ecolodge with a capacity of 60guests, located approximately 60km from the

city of Puerto Maldonado.

The Agami heron colony occurs at the farwestern end of Cocococha Lake. Thecolony is distributed in a semi-circle

around the end of the lake in an area ofapproximately 150m x 30m (see Figure

1). Other species present at the siteincluded Hoatzin (Opisthocomus hoazin)

and Anhinga (Anhinga anhinga).

Cocococha Lake is currently utilised by

Explorers Inn lodge for eco-tourism andresearch purposes. The majority of guests at

the lodge visit Cocococha, however, boat

access is restricted to a small portion of thelake (Figure 1) and they must be accompanied

8/9/2019 agami_heron_report vikki thompson

2/4

by a guide. The area of the lake utilised by theAgami heron colony is off-limits to tourists

and is only very rarely visited by researcherswho follow strict guidelines to prevent

disturbance to the colony.Cocococha Lake also lies within the

Indigenous Area of Infierno Community whoutilise the lake and surrounding areas for

subsistence hunting, collecting and fishing.However, members of the community do not

have boat access onto the lake itself and as thearea utilised by the Agami herons is fairly

inaccessible by foot it appears that this area is

rarely visited by Infierno community.

RESULTS

Agami herons first began to use this site in

1991, when six breeding pairs were seen to bebreeding (E. Armas, 2007, pers. comm. 5January) In 2001 the colony began to increase,

and has since been increasing to its current size(E. Armas, 2007, pers. comm. 5 January).

Nesting occurs in the rainy season. In2005 the whole colony was found to be present

at the site in late November; however, in 2006the first birds were not sighted until 19 th

December (6 birds). The full colony waspresent by 11th January. Nests were located

in bushes around the lakeshore, to a depth ofapproximately 20m from the lake edge. Nests

were between 0.5 and 3.5m above water.At the beginning of the breeding season, in lateDecember and January, beak duels were

common between the herons. Throughout the

day many birds were engaged in these duelswhich often lasted 30 minutes or more. The

loud sound of this rapid clicking of beakswas audible from a distance of at least 50m.

During this period of time what is presumed tobe the male herons also had a distinctive red

colouration on their cheeks. This lastedthroughout the courtship stage until the

beginning of February.

Nest building began in early January andwas completed by 20th January. On 23rd

February large chicks, of around 20cm in

length, were sighted sitting in nests; by 15th

March some chicks had fully fledged and were

seen perched on, and flying between bushes.On 15th March, however, some herons were

still incubating the characteristic bright blueeggs of Agami herons. By the end of this

study, on 3rd April 2007, there were few herons

still sat on nests; large numbers of fullyfledged juveniles were present in the colony

and it appeared that some adults had left the

breeding colony altogether.

The number of visible nests was countedon 23rd February. 123 nests were counted in

total. The maximum number of birds countedwas 287 (11th January). The mean average of

birds counted during mid-January to mid-March was 272.

The characteristic low pitched rattling callof the species, called the Gr call (Kushlan &

Hancock, 2005) was given by the colonythroughout the day. This continued on

approach by the boat. Nest shading, andshading of juveniles as described by Reynaud

& Kushlan, (2004) was also observed.

An interesting observation occurred on 23rd

February when brown capuchin monkeys

(Cebus apella) were seen to predate eggs of the

Agami Heron colony. Noise level of the Grcall increased considerably and movement of

the herons between branches increased. Two

Brown Capuchin monkeys then came intoview, which were seen to take eggs from nestsof the herons. One monkey was seen to take 2

eggs, and another, one egg. These were thetaken to nearby aguaje palm tress where they

were consumed by the monkeys. It waspossible that more monkeys were present,

although only 2 were sighted. Shortly after thedeparture of the monkeys, noise levels and

movement of the birds reduced to a normallevel.

DISCUSSION

There are a number of reports of colonial

nesting of the Agami Heron (Micheneret al. 1964; de Vries 1968; Ramo &Busto1982; Marin 1989; Haverschmidt &Mees1994; Jones, 2002 and Reynaud &Kushlan, 2004). Much of the earlierliterature reports small colonies ofonly a few pairs of herons, however;

recently, a colony of over 80 nestswas reported in Belize (Jones, 2002)and a particularly large colonyestimated at around 900 nests wasreported in French Guiana (Reynaud& Kushlan, 2004). As the colony inFrench Guiana is only accessible byhelicopter, this colony, with at least123 nests, appears to be one of thelargest and most accessible breedingcolonies of Agami Herons.

Along with high availability offood, it has been suggested that

isolation and protection of sites maybe a factor in the suitability of a siteto support large numbers of breeding

8/9/2019 agami_heron_report vikki thompson

3/4

herons (Reynaud & Kushlan, 2004).Reynaud and Kushlan (2004) alsonote that behaviour of the colonysuggests site security is important.The site at Cocococha is situatedwithin the fully protected Tambopata

National Reserve and although easilyaccessible by boat, is at thismoment, relatively undisturbed byhuman activity. This protection ofthe site, along with a high availabilityof food are likely to be importantfactors in the attractiveness of thesite to the herons.The arrival of Agami Herons at thebreeding site appears to be stronglylinked with the arrival of the rainyseason. In 2005, the rainy season

began in November and the colonywas present by late November. In2006, the rainy season started laterthan usual and the first birds did notbegin to arrive until late December.The link between breeding of theherons and the rainy season is likelyto be due to a greater availability offood at this time.

Both movement of herons to andfrom the colony, and feeding ofyoung, were not observed atCocococha. Agami Herons are knownto enter and leave breeding sites indarkness (Reynaud & Kushlan, 2004)and it is possible that these heronsmay have been moving in the hoursof darkness between 6pm and7.30am. As no birds were seenentering or leaving the colony,nothing is known about the directionsof flight, or areas in which they maybe feeding.

It may also be possible that themaximum count of 287 herons

observed during daytime hours onlyrelates to a percentage of heronsactually breeding at the site.Reynaud and Kushlan (2004)observed that of 122 nests inspectedduring daylight hours, 75% wereunattended by adults. However,observations at Cocococha suggestthat most visible nests were attendedby at least one parent during daylighthours.

It has been suggested that AgamiHerons appear to be quite different

from other heron species (Reynaud &Kushlan, 2004). There is much

ground for further study of thisspecies and the accessibility of thiscolony provides much scope forfurther study. It is, however, vitallyimportant that the colony andsurrounding area keep the protection

currently afforded and remain freefrom human disturbance in order toensure the longevity of this largecolony of rare and secretive birds.

REFERENCES

De Vries, P. J. 1968. Nesting ofAgamia

agami.In F.Haverschmidt, Birds of Surinam.Edinburg & London.

Hancock, J. and J. A. Kushlan. 1984. The

Herons handbook. Crom Helm, London &Sydney.

Haverschmidt, F. and G. F. Mees. 1994. Birds

of Surinam. Vaco, Uitgeversmaatschappij,Paramaribo.

Jones, H. L. 2002. Central America. North

American Birds 56:484-495.

Kushlan, J. A. and J. A. Hancock. (2005). Theherons. Oxford University Press, Oxford.

Marin, M. 1989. Notes on the breeding of

Chesnut-bellied Herons (Agamia agami) inCosta Rica. Condor 91: 215-217.

Michener, M. C., J. S. Weske and R. B. Clapp.

1964. A breeding colony of Agami Herons inVeracruz. Condor 66: 77-78.

8/9/2019 agami_heron_report vikki thompson

4/4

Ramo, C. and B. Busto. 1982. Notes on thebreeding of the Chesnut-bellied Herons

(Agamia agami) in Venezuela. Auk 99: 784.

Reynaud, P.A and Kushlan, J.A. (2004).Nesting of the Agami Heron. Waterbirds 27

(3): 308-311.

Author:Victoria Thompson BSc (hons) AIEEM

7 High Portinscale, Keswick, Cumbria,CA12 5RN, ENGLAND.

Tel: 00441768773495

E-mail: vikkithompson1@hotmail.com