Breeding of the Brown Creeper (Certhia americana) in Central America.
Abstract: We report the first nesting record of the Central American population of Brown Creeper (Certhia americana) in the La Montanona pine-oak (Pinus-Quercus) forest of Chalatenango Department, northern El Salvador. The nest was in a cavity in the trunk of a pine (Pinus oocarpa) tree. Most insectivorous birds in this region breed during the rainy season when insects are generally most abundant; however, nesting of the Brown Creeper occurred at the height of the dry season, during January and February.
Article Type: Report
Subject: Nest building (Research)
Authors: Funes, Carlos
Bolanos, Oscar
Komar, Oliver
Pub Date: 03/01/2012
Publication: Name: The Wilson Journal of Ornithology Publisher: Wilson Ornithological Society Audience: Academic Format: Magazine/Journal Subject: Biological sciences Copyright: COPYRIGHT 2012 Wilson Ornithological Society ISSN: 1559-4491
Issue: Date: March, 2012 Source Volume: 124 Source Issue: 1
Topic: Event Code: 310 Science & research
Geographic: Geographic Scope: El Salvador Geographic Code: 2ELSA El Salvador
Accession Number: 285207261
Full Text: The avian breeding season in the tropics is less well defined than in temperate zones, where breeding is constricted by climate. Avian breeding in tropical areas can extend over a longer period; some species, especially columbids, may breed year-round. Nectarivores such as hummingbirds (Trochilidae) and flowerpiercers (Diglossa spp.) typically breed during the dry season, when many plants are in flower. Most insectivorous birds time their breeding to match hatching with the onset of the rainy season, when insect abundance greatly increases (Skutch 1950). El Salvador, in northern Central America, has extremely marked wet and dry seasons. Most hatching of insectivorous birds occurs in May and June, similar to the breeding season in North American temperate zones (Dickey and van Rossem 1938).

The Brown Creeper (Certhia americana) is an insectivorous bark gleaner, distributed from North America to Mexico, and through mountainous areas of Guatemala and Honduras to northwest Nicaragua (Hejl et al. 2002). The species has been found since 1999 in all major pine-oak (Pinus-Quercus) forests of El Salvador along the northern border near Honduras between 1,175 and 1,850 m elevation (Komar 2002; OK, unpubl, data).The population resident in the mountains of eastern Guatemala, Honduras, northwestern Nicaragua, and presumably El Salvador, is known as Certhia americana extima, one of 13 recognized subspecies (Hejl et al. 2002). Hejl et al. (2002) report nesting in U.S. and Canada from April through July, and Land (1962) collected a male in Sierra de las Minas in eastern Guatemala with partially enlarged testes on 5 March.

We encountered an active nest of Brown Creeper during field work on the ecology of wintering birds in pine-oak forests. We observed the nest briefly during 2 days, documenting it with measurements and photographs, and observing behavior of the adults and nestlings.

OBSERVATIONS

Nest observations occurred during 1130-1230 and 1520-1625 hrs on 5 February 2010 at the La Montanona Forest, a protected natural area. We returned to photograph the nest and nestlings on 6 February 2010. This site is in the central part of Chalatenango Department, El Salvador, near the Honduras border. The specific site of the nest observation was 14[degrees] 08' 39" N, 88[degrees] 54' 25" W at 1,470 m elevation in the La Laguna municipality. The natural area contains ~2,500 ha of pine-oak forest, ranging from 900 to 1,600 m elevation.

An active Brown Creeper nest was located in a natural cavity -5 m above ground in the trunk of a 25-m pine (Pinus oocarpa), in somewhat open pine-oak forest. The cavity had a single entrance (Fig. 1A). The nest cavity was 28 cm high, from the nest cup at its base to the cavity roof, and 13 cm deep. Cavity width ranged from 2 to 5 cm. The nest cup, constructed mostly of dry pine needles, beard lichen (probably Usnea sp.), and mosses, measured -5 cm in diameter (Fig. 1B).

We observed two adults taking turns feeding three nestlings and removing fecal sacs from the nest. The adults, often together, visited the nest every 2 to 30 min (n = 8, mean [+ or -] SD = 10.1 [+ or -] 9.5 min). A passing Ivory-billed Woodcreeper (Xiphorhynchus flavigaster) extracted one of the nestlings while we watched, and flew away with the nestling hanging from its bill, dropping the nestling before disappearing, some 50 m distant near a ravine.

[FIGURE 1 OMITTED]

DISCUSSION

The timing of breeding in the middle of the dry season, when insectivores generally are not nesting and populations of visiting migratory birds are high, is of interest. We found nestlings, 1 week of age, on 5 February. Given an average incubation period of 15 days for Brown Creepers (Hejl et al. 2002), and laying of one egg per day, we estimate that egg-laying in El Salvador began ~12 January. Most other insectivorous bark gleaners in Central America are reported to breed later in the year (Table 1). The only other insectivorous bird species in Central America reported to breed in January or February (Skutch 1969) is the Lineated Woodpecker (Dryocopus lineatus) which occupies a similar feeding niche (tree bark) as the creeper, but is more than 20 times heavier. Some Golden-fronted Woodpeckers (Melanerpes aurifrons) may also begin egg-laying in early February (Skutch 1969).

We do not have evidence that creepers or any other birds breed regularly or frequently during the dry season in the pine-oak forest ecosystem in El Salvador. We searched the La Montanona pine-oak forest for birds during 5 days each winter from 2007 to 2010, and invested equal efforts at three similar sites in El Salvador where Brown Creepers also were found. We spent 16 weeks observing the dry-season bird communities in pine-oak forest of El Salvador. The only indication of nesting behavior of any bird species other than the nest reported here was the observation of a pair of Lineated Woodpeckers widening a potential nest hole in December 2008. Bird monitoring data from a mist-netting station in pine-oak forest at Montecristo National Park provided no indication of insectivorous birds in breeding condition during January or February, despite 5,600 net hrs during those months (SalvaNATURA, 2003-2009, unpubl, data).

One Brown Creeper at Montecristo National Park, captured on 10 April 2008 and classified as second year, was molting contour feathers and still retained heavily worn juvenile flight feathers; this is consistent with hatching during February 2007. The bird had a completely ossified skull (confirming it was likely born the previous year), and no fat, consistent with a resident, nonmigratory individual. The bird was not in breeding condition. We have heard Brown Creepers singing from February to July at Montecristo National Park. Singing is suggestive of breeding behavior, although migratory birds in more northern wintering areas occasionally sing during the nonbreeding season (OK, pers. obs.).

Winter nesting in Central America raises questions about the ecology of Brown Creepers. The species is assumed to be a permanent resident in Central America, but the observation of nesting in winter raises the possibility that northern populations migrating to Mexico or as far south as Central America (which has not been documented) could conceivably encounter resources sufficient for double nesting, which has been reported recently for other migratory species (Rohwer et al. 2009). Early nesting in Central America also may indicate the local subspecies is on a separate evolutionary track from more northern subspecies and may eventually evolve phenological barriers to gene flow.

ACKNOWLEDGMENTS

This study was conducted while undertaking monitoring work funded by Texas Parks and Wildlife Department with funds from the U.S. Fish and Wildlife Service. The Ministry of Environment and Natural Resources of El Salvador provided the research permit. Local lodging and land access was granted by the Comite Representativo de Beneficiarios de La Montanona (CORBELAM). Roselvy Juarez collected data from a captured Brown Creeper at Montecristo National Park as part of the Permanent Bird Monitoring Program conducted by SalvaNATURA. We are grateful to C. E. Braun, Knut Eisermann, and Steven Latta, for comments that improved the manuscript.

Received 19 April 2011. Accepted 15 August 2011.

LITERATURE CITED

DICKEY, D. R. AND A. J. VAN ROSSEM. 1938. The birds of El Salvador. Field Museum of Natural History, Chicago, Illinois, USA.

HEJL, S. J., K. R. NEWLON, M. E. MCFADZEN, J. S. YOUNG, AND C. K. GHALAMBOR. 2002. Brown Creeper (Certhia americana). The birds of North America. Number 669.

KOMAR, O. 2002. The birds of Montecristo National Park. Ornitologia Neotropical 13:167-193.

LAND, H. C. 1962. A collection of birds from the Sierra de las Minas, Guatemala. Wilson Bulletin 74:267-283.

ROHWER, S., K. A. HOBSON, AND V. G. ROHWER. 2009. Migratory double breeding in neotropical migrant birds. Proceedings of the National Academy of Sciences of the USA. 106:19050-19055.

SKUTCH, A. F. 1950. The nesting season of Central American birds in relation to climate and food supply. Ibis 92:185-222.

SNUTCH, A. F. 1969. Life histories of Central American birds. III. Pacific Coast Avifauna 35:374-547.

VEGA RIVERA, J. H., D. AYALA, AND C. A. HAAS. 2003. Home-range size, habitat use, and reproduction of the Ivory-billed Woodcreeper (Xiphorhynchus flavigaster) in dry forest of western Mexico. Journal of Field Ornithology 74:141-151.

Carlos Funes, (1) Oscar Bolanos, (1) and Oliver Komar (1, 2, 3)

(1) Programa de Ciencias para la Conservacion, SalvaNATURA, Colonia Flor Bianca, 33 Avenida Sur #640, San Salvador, El Salvador.

(2) Present address: Instituto Regional de Biodiversidad, Zamorano University, Km 35, Carretera a Danli, Francisco Morazan, Honduras.

(3) Corresponding author; e-mail: okomar@zamorano.edu
TABLE 1. Reported nesting season for selected Central American bark-
gleaning insectivorous bird species.

Species                                             Earliest
                                                    reported
                                                    egg dates

Ivory-billed Woodcreeper                            Apr
  (Xiphorhynchus flavigaster)
Spot-crowned Woodcreeper (Lepidocolaptes affinis)   Apr
Streak-headed Woodcreeper (L. souleyetii)           Late Mar
Golden-fronted Woodpecker (Melanerpes aurifrons)    Early Feb
Lineated Woodpecker (Dr yocopus lineatus)           Jan (possibly
                                                    late Dec)
Hairy Woodpecker (Picoides villosus)                Apr

Species                                             References

Ivory-billed Woodcreeper                            Dickey and van
  (Xiphorhynchus flavigaster)                       Rossem 1938, Vega
                                                    Rivera et al. 2003
Spot-crowned Woodcreeper (Lepidocolaptes affinis)   Skutch 1969
Streak-headed Woodcreeper (L. souleyetii)           Skutch 1969
Golden-fronted Woodpecker (Melanerpes aurifrons)    Skutch 1969
Lineated Woodpecker (Dr yocopus lineatus)           Skutch 1969
Hairy Woodpecker (Picoides villosus)                Skutch 1969
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