Morphological, olfactory, and vocal development in big brown bats

Abstract

Using a within subjects design, we documented morphological, bioacoustical and behavioral developmental changes in big brown bats. Eptesicus fuscus pups are born naked and blind but assume an adult-like appearance by post-natal day (PND) 45 and flight by PND 30. Adult females use spatial memory, acoustic and olfactory cues to reunite with offspring, but it is unclear if pups can recognize maternal scents. We tested the olfactory discrimination abilities of young E. fuscus pups and found they exhibited no odor preferences. Pups also emit distinct vocalizations called isolation calls (i-calls) that facilitate mother-offspring reunions, but how pups shift their vocalizations from i-calls to downward frequency modulated (FM) sweeps used in echolocation remains unclear. Between PND 0–9, pups emitted mainly long duration, tonal i-calls rich in harmonics, but after they switched to short duration, downward FM sweeps with fewer harmonics. Call maximum frequency and repetition rate showed minor changes across development. Signal duration, bandwidth, and number of harmonics decreased, whereas the maximum, minimum and bandwidth of the fundamental, and peak spectral frequency all increased. We recorded vocalizations during prolonged maternal separation and found that isolated pups called longer and at a faster rate, presumably to signal for maternal assistance. To assess how PND 13 pups alter their signals during interactions with humans we compared spontaneous and provoked vocalizations and found that provoked calls were spectrally and temporally more similar to those of younger bats suggesting that pups in distress emit signals that sound like younger bats to promote maternal assistance.

Social communication in bats

“…Mother–infant reciprocal signalling and recognition is known for some species [ Rousettus aegyptiacus (Kulzer, ); Pteropus poliocephalus (Nelson, ); Myotis lucifugus (Turner, Shaughnessy & Gould, ); Rhinolophus ferrumequinum (Matsumura, )], and antiphonal calling – a duet between mother and offspring – may also occur (Matsumura, ; Brown, Brown & Grinnell, ; Balcombe & McCracken, ). In species showing unidirectional recognition, female echolocation or directive calls [emitted in response to i‐calls (Brown, ; Matsumura, ; Esser & Schmidt, ; Balcombe & McCracken, ; Knörnschild & von Helversen, )] may encode individual identity (Yovel et al, ; Voigt‐Heucke et al, ; Jones & Siemers, ) that is recognized by adults (Boughman & Wilkinson, ; Pfalzer & Kusch, ) but not by pups, which neglect their mother's acoustic signals or olfactory cues (Balcombe, ; Knörnschild & von Helversen, ; Mayberry & Faure, ).…”

“…Isolation calls have been found to attract mothers both in natural (Watkins & Shump, 1981;Bohn, Wilkinson & Moss, 2007) and experimental settings (Matsumura, 1979;Balcombe, 1990;De Fanis & Jones, 1995;Schmidt-French et al, 2006;Bohn et al, 2007;Knörnschild, Feifel & Kalko, 2013). Call rates increase when pups are separated for longer periods (Matsumura, 1979;Mayberry & Faure, 2014) or their body temperature decreases (Camaclang, Hollis & Barclay, 2006), probably encoding the pup's status or motivation and thus altering the mother's response (Camaclang et al, 2006). Distressed Eptesicus fuscus young change i-call parameters to make calls similar to those produced at an earlier age and elicit a more rapid response from their mothers (Mayberry & Faure, 2014).…”

“…Call rates increase when pups are separated for longer periods (Matsumura, 1979;Mayberry & Faure, 2014) or their body temperature decreases (Camaclang, Hollis & Barclay, 2006), probably encoding the pup's status or motivation and thus altering the mother's response (Camaclang et al, 2006). Distressed Eptesicus fuscus young change i-call parameters to make calls similar to those produced at an earlier age and elicit a more rapid response from their mothers (Mayberry & Faure, 2014).…”

Гидроакустические Закономерности Пищевого Поведения Дельфинов

“…Гармоники внутренне присущи этому типу акустических сигналов дельфина. Следует специально отметить, что ЧМ-сигналы с такой же полосой частот и наличием гармоник используют летучие мыши в качестве зондирующих сигналов их эхолокатора [21,27,28]. В теории и технике эхолокации подобные ЧМсигналы, но без гармоник, применяются как зондирующие сигналы ЧМ-сонаров со сжатием импульса и ЧМ-доплеровских сонаров (и подобных радаров).…”

Frequency tuning of synaptic inhibition underlying duration-tuned neurons in the mammalian inferior colliculus

“…When they occurred, poststimulatory effects were most frequent when the NE tone was set to the cell's BEF. One interesting possibility is that cells with poststimulatory elevated spike counts could be displaying a weak form of delay tuning (Macías et al 2012;Wenstrup 1999, 2001) and/or interval tuning (Leary et al 2008), and such responses may help E. fuscus process ecologically relevant combinations of long-and short-duration sounds separated in time (e.g., during mother-pup social interactions; Mayberry and Faure 2014;Monroy et al 2011). Future studies should continue to explore any relationship that exists between duration tuning and delay tuning.…”