Resting together, foraging apart: Network structure of foraging bats is not explained by energy expenditure or foraging efficiency

Group foraging animals may change their spatial relationships in response to the resource landscape. The strength of social network ties across foraging groups could then reflect the energy balance of individual group members through their effect on foraging efficiency. To test this, we tracked individuals in three social groups of Phyllostomus hastatus (greater spear-nosed bats) in Bocas del Toro, Panama. Phyllostomus hastatus seasonally feed on balsa flowers, and group-specific social calls are hypothesized to coordinate social foraging. We found that bats commuted alone but then joined group members in small foraging patches with high densities of flowering balsas, approximately 25 km from their roost. Their estimated energy expenditure was not related to their proximity social network, and network strength did not predict foraging efficiency. Bats in the same foraging patch did not coordinate foraging movement, but close proximity among individuals increased resting bout duration and synchrony. Bats across all social groups used the same resting areas, potentially due to the resting site's physical characteristics, proximity to abundant food resources or predation avoidance. These results indicate that factors other than increased feeding efficiency may structure network relationship of group members while foraging.

Plaguicidas organoclorados en murciélagos (Chiroptera) asociados al bosque húmedo tropical en Córdoba, Colombia

Investigaciones sobre toxicidad ambiental por pesticidas se han realizado principalmente en mamíferos terrestres, pero existe poca información sobre plaguicidas organoclorados en murciélagos. Teniendo en cuenta el papel funcional de este grupo en varios procesos ecosistémicos como insectívoros, frugívoros y polinizadores, su afectación puede estar causando un impacto negativo en la salud de los ecosistemas naturales. En Colombia, no hay estudios que documenten esta problemática; por tanto, el objetivo fue determinar la presencia de plaguicidas organoclorados en el ensamblaje de murciélagos del bosque húmedo tropical (bh-T) en Córdoba, Colombia. Se evaluó la presencia de organoclorados en hígado y músculo de murciélagos del sector Manso-Tigre, un área protegida con ocupación campesina. La concentración de plaguicidas organoclorados como Aldrin, Dieldrin, Endrin, Heptacloro epóxido, α-BCH, βBCH, γ-BCH, 2,4-DDD, 2,4-DDT, 4,4-DDE y 4,4-DDT, se determinó por cromatografía de gases. Niveles de organoclorados en hígado y músculo presentaron diferencias significativas (P<0,05). Se detectó mayor contenido de organoclorados en hígado en las especies Trachops cirrhosus (α–BCH, γ-BCH, Endrin, pp-DDE), Desmodus rotundus (β-BCH), Micronycteris microtis (Aldrin), Platyrrhinus helleri (Heptacloro) y Phyllostomus hastatus (pp-DDT). En tejido muscular, la concentración de organoclorados fue mayor en Trachops cirrhosus (α-BCH, γ-BCH, Endrin, pp-DDE), Artibeus planirostris (β-BCH), Micronycteris microtis (Aldrin, Heptacloro) y Phyllostomus hastatus (pp-DDT). La contaminación por organoclorados en murciélagos posiblemente está relacionada con el uso de agroquímicos, insecticidas y compuestos fosfatados para uso agrícola. Los resultados permiten reconocer a los murciélagos como bioindicadores de contaminación ambiental al indicar procesos de cambios o disturbios en los hábitats.

Fauna de ectoparásitos en el vampiro común Desmodus rotundus (Geoffroy, 1810) (Chiroptera: Phyllostomidae) de Huarochiri, Lima, y una lista de los ectoparásitos en murciélagos del Perú

El murciélago hematófago Desmodus rotundus (Geoffroy, 1810) es una especie de importancia zoonótica y amplia distribución. El propósito de este estudio fue evaluar su fauna ectoparasitaria y elaborar una lista de los artrópodos parásitos presentes en los murciélagos del Perú. Los murciélagos fueron capturados en el distrito de San Bartolomé, provincia de Huarochirí, Lima, Perú. La preparación de la lista se llevó a cabo mediante la búsqueda en las principales bases de datos en línea. Se estudiaron 27 murciélagos, de los cuales el 70,37 % (n = 19) estaban infectados con al menos una especie de ectoparásito. Se registraron las especies de Diptera Strebla wiedemanni Kolenati, 1856, y Trichobius parasiticus Gervais, 1844, y el ixódido Ornithodoros peruvianus Kohls, Clifford & Jones, 1969. La especie de mayor abundancia y prevalencia fue O. peruvianus. Se reportan tres especies de piojos en D. rotundus, que consideramos como parásitos accidentales. En cuanto a la lista, hasta la fecha se han reportado 104 especies de ectoparásitos distribuidos entre los grupos principales: Diptera, Hemiptera, Siphonaptera, Phthiraptera, Mesostigmata e Ixodida a partir de ejemplares de 75 especies de murciélagos en 19 departamentos del Perú. Aspidoptera falcata Wenzel, 1976, y Megistopoda aranea (Coquillett, 1899) (Streblidae) son los ectoparásitos con el mayor número de huéspedes registrados. Lophostoma silvicolum d’Orbigny, 1836; Phyllostomus elongatus (Geoffroy, 1810) y Phyllostomus hastatus (Pallas, 1767) son los huéspedes con el mayor registro de ectoparásitos en murciélagos del Perú (s = 10). Según el nivel de especificidad de los ectoparásitos para sus huéspedes, las especies monoxenas (s = 47) fueron las dominantes, seguidas por las oligoxenas (s = 21). Las regiones geográficas con mayor información acerca de ectoparásitos huéspedes fueron Loreto y Madre de Dios. Es necesario ampliar los estudios ya que el 60.3% de las especies de murciélagos del Perú no tienen registros de ectoparásitos.

Cytoarchitecture of the medial nucleus of trapezoid body of three neotropical species of bats (Noctilio leporinus, Phyllostomus hastatus, and Carollia perspicillata) with different foraging behavior

The present study was taken to test the hypothesis that the medial nucleus of the trapezoid body (MNTB) of echolocating neotropical bats with different foraging behavior will exhibit morphological variations in relative size, degree of complexity and spatial distribution. The brains were collected from six male adult bats of each species: Noctilio leporinus (fish-eating), Phyllostomus hastatus (carnivorous/ omnivorous) and Carollia perspicillata (fruit-eating) and were double-embedded and transverse serial sections were cut and stained with cresyl fast violet. The results showed that the MNTB is well developed in all the bats in general and the mean length of the MNTB was 1160 ± 124 µm in N. leporinus, 400 ± 59 µm in P. hastatus and 320 ± 25µm in C. perspicillata. The body and brain weight do not reflect proportionately on the size of the MNTB in the present study. The hearing frequency spectrum did not covary with the size of the MNTB among the bats studied. The MNTB is clearly demarcated from the ventral nucleus of the trapezoid body (VNTB) only in P. hastatus. The MNTB comprised mainly three types of cells in all three bats: dense-staining multipolar cells (12.5 µm and 25.0 µm diameter); light-staining multipolar cells measuring (12.5 µm and 25.0 µm diameter) and light-staining round cells (5.0 µm diameter). The large sized MNTB was observed in N. leporinus, which suggests that it relies heavily on echolocation whereas P. hastatus and C. perspicillata use echolocation as well but also rely on hearing, smell and vision.

Cytoarchitecture of the superior olivary complex of three neotropical species of bats (Noctilio leporinus, Phyllostomus hastatus and Carollia perspicillata) with different foraging behavior

The understanding of the echolocation by studying different auditory nuclei of echolocating bats can be an important link in elucidating questions arising in relation to their foraging behavior. The superior olivary complex (SOC) is the primary center for processing the binaural cues used in sound localization since echo locating bats rely on acoustic cues to navigate and capture prey while in flight. The present study was taken to test the hypothesis that the SOC of echolocating neotropical bats with different foraging behavior will exhibit morphological variations in relative size, degree of complexity and spatial distribution. The brains were collected from six male adult bats of each species: Noctilio leporinus (fish eating), Phyllostomus hastatus (carnivorous/omnivorous) and Carollia perspicillata (fruit eating). They were double-embedded and transverse serial sections were cut and stained with cresyl fast violet. The SOC measured as 640 ± 70 µm in the N. leporinus bat, 480 ± 50 µm in the P. hastatus and 240 ± 30 µm in the C. perspicillata bat. The principal nuclei of the SOC of in all three bats were the LSO, MSO and MNTB. The MSO and LSO were very well developed in N. leporinus bats. The MSO of N. leporinus bat subdivided into DMSO and VMSO. The main cell type of cells present in MSO and LSO are dark staining multipolar cells in all the bats studied. The well-developed MSO and LSO of N. leporinus bats indicate that these bats are highly sensitive to low frequency sounds and interaural intensity differences, which help these bats to forage over water by using various types of echolocation signals. The average size of SOC in P. hastatus and C. perspicillata bats can be attributed to the fact that these bats use vision and smell along with echolocation to forage the food.

Biologia de Phyllostomus hastatus (Pallas, 1767) (Chiroptera, Mammalia) em dois parques urbanos no Estado do Rio de Janeiro, Brasil

Studies about bats biology encompassing diet, reproduction and parasitology are important to understand the role of these small animals in the ecosystem. However, few studies present such information. Therefore, the present paper was made to congregate information about biology of Phyllostomus hastatus, and compare the results between two urban parks at Rio de Janeiro City (Rio de Janeiro, Brazil): Parque Natural Municipal da Freguesia (PNMF) and Parque Estadual da Pedra Branca (PEPB), the latter being considerably larger than the other one. Long-term fieldworks were conducted in both areas and data on biometry, reproduction, parasites and diet were assembled. Animals were captured in mists nets and put in cotton sacs, from where fecal material was collected for further analysis. They were measured alive and inspected for reproductive stage; ectoparasites were collected and blood smears were made whenever possible. Bats were released at the end of the fieldwork. The feces and blood material were analyzed at the lab. Thus, 53 specimens of Phyllostomus were captured, 13 from PNMF and 40 from PEPB. We found individuals with smaller measurements at the most anthropized park – the Freguesia Park; reproduction occurred between September and December at both parks; diet included Curcubitaceae, Urticaceae, Bombacaceae, Lythraceae, Coleoptera, Lepidoptera, Hemiptera and Diptera. Concerning ectoparasites, Diptera and Acari were recorded; no haemoparasites were found in the blood smears. Although specimens from the smaller park seem to be most affected by anthropization, our results reinforce the idea that the creation of small parks is important for species maintenance, since it may serve as ecological corridor and as a food source for the animals.

El tamaño, pero no la forma, reflejaría diferencias en las mandíbulas de dos especies de murciélagos de hoja nasal (Phyllostomus Lacépède, 1799) (Chiroptera, Phyllostomidae)

La mandíbula es un modelo para la evolución de las estructuras morfológicas complejas debido a que presenta una integración del desarrollo de sus diferentes estructuras. A diferencia de otras partes del cráneo, que albergan estructuras con funciones diferentes (protección del cerebro y de los órganos sensoriales), la principal demanda funcional para la mandíbula se relaciona con la alimentación. Por ello, es esperable que sea la dieta su principal agente selectivo. En esta investigación se presenta un estudio basado en morfometría geométrica, de mandíbulas pertenecientes a dos especies de murciélagos de hoja nasal, Phyllostomidae: el murciélago nariz de hoja pálido (Phyllostomus discolor Wagner, 1843) (n= 29) y el murciélago nariz de hoja lanceolada [Phyllostomus hastatus (Pallas, 1767)] (n= 6), ambas especies omnívoras, con tendencia nectarívora. Las diferencias en tamaño y forma de la mandíbula fueron examinadas usando 13 hitos anatómicos situados en la cara lateral de las hemimandíbulas. Los resultados revelaron diferencias entre ambas especies para el tamaño, pero no para la forma, siendo insignificante la variación alométrica. Se concluye que una alimentación parecida para ambas especies ha hecho evolucionar hacia una forma mandibular similar, aunque el tamaño para ambas haya evolucionado de manera independientemente.

Infracommunities of Streblidae and Nycteribiidae (Diptera) on bats in an ecotone area between Cerrado and Atlantic Forest in the state of Mato Grosso do Sul

ABSTRACT We described infracommunities, prevalence and mean intensity of infestation of ecotoparasite flies (Nycteribiidae and Streblidae) on bats in an ecotone area of Cerrado as predominant vegetation, with influence of Atlantic Forest, in the southeast of Mato Grosso do Sul. In 36 sampling nights between April 2015 and August 2016 (23,328 m².h), we captured 17 bat species, of which ten were infested, and 14 species of fly. The most abundant bats were the phyllostomids Artibeus planirostris (Spix, 1823), Glossophaga soricina (Pallas, 1776) and Carollia perspicillata (Linnaeus, 1758) and the most abundant flies were the streblids Trichobius longipes (Rudow, 1871), T. joblingi Wenzel, 1966 and Megistopoda aranea (Coquillett, 1899). Phyllostomus hastatus (Pallas, 1767) was the bat species that presented the highest infestation rate. Platyrrhinus lineatus (É. Geoffroy, 1810) and Desmodus rotundus (É. Geoffroy, 1810) were not infested. Besides that, the frequency of bats that were infested by a single species of fly was higher than the frequency of bats infested for two or more, and it may be a pattern.