scholarly journals Niche segregation of sand lizard (Lacerta agilis) and green lizard (Lacerta viridis) in an urban semi-natural habitat

2015 ◽  
Vol 36 (4) ◽  
pp. 389-399 ◽  
Author(s):  
Botond Heltai ◽  
Péter Sály ◽  
Dániel Kovács ◽  
István Kiss

Different types of semi natural habitats has important role in long-term survival and maintenance of reptile species in urban environments. Heterogeneous urban green islands can provide conditions that enable competing species to live together in relatively small areas. However, the key mechanism of coexistence could vary from types of habitats and taxa. We investigated the population structure, the fine scale habitat segregation and diel activity pattern of two lizard species (Lacerta viridis and L. agilis) coexisting populations in a town cemetery. We hypothesized, that fine scale habitat segregation is a more important factor in coexistence than differences in diel activity pattern, because of the environmental dependent thermoregulation constrain. During the study, 178 L. agilis and 79 L. viridis occurrences were recorded. The daily activity patterns of both species were very similar, with peaks found in the forenoon and afternoon. Lizards were found to be the most active at 31-32°C. The probability of occurrence of the species was influenced more by the differences in the random selection of parcels rather than the random differences in the survey days. Around the proximate observation point the bush covered areas was significantly higher than average in the parcels. Our results showed that niche segregation based on fine scale habitat patches had a fundamental role in the coexistence of the two lizard species. L. agilis preferred the more open spaces, whereas L. viridis preferred areas with more bushes, but there was no difference in the daily activity pattern of the two species.

2010 ◽  
Vol 8 (4) ◽  
pp. 893-898 ◽  
Author(s):  
Leo G. Nico

Several Pterygoplichthys species, members of the Neotropical catfish family Loricariidae, have been widely introduced outside their native ranges. In this paper, I present observations on the diel activity pattern of non-native Pterygoplichthys, tentatively identified as P. disjunctivus, with respect to their attachment and grazing on endangered Florida manatees, Trichechus manatus latirostris. The study was conducted in December 2009 at Volusia Blue Spring, an artesianal spring system in the St. Johns River basin, Florida (USA). Supplemented by information gathered during previous visits to the spring site, this study revealed that adult Pterygoplichthys are active throughout the diel period (day, twilight and night). However, juvenile Pterygoplichthys were largely nocturnal and only at night did they consistently join adults in attaching to manatees. The juveniles generally remain hidden during the day, probably responding to presence of diurnal predators, mainly birds. Differences in diel behaviors among different Pterygoplichthys size classes in Florida are consistent with published observations on loricariids inhabiting clearwater streams within their native ranges.


1980 ◽  
Vol 37 (9) ◽  
pp. 1454-1458 ◽  
Author(s):  
James S. Diana

Movements of six northern pike (Esox lucius) were monitored for 5 to 51 days by ultrasonic transmitters implanted surgically. The pike were inactive during 80% of the eight hundred and eighty-nine 5-min intervals monitored during summer and winter. No regular diel changes in activity were noted, except that pike were inactive at night. Swimming velocities calculated from gross displacements were maximum, 42 cm/s (0.91 body lengths (BL)/s); average, 23.1 cm/s (0.45 BL/s).Key words: movements, diel activity, seasonal activity, northern pike, Esox lucius; swimming speeds


2019 ◽  
Vol 11 (8) ◽  
pp. 13960-13966
Author(s):  
Kangaraj Muthamizh Selvan ◽  
Bawa Mothilal Krishnakumar ◽  
Pasiyappazham Ramasamy ◽  
Thangadurai Thinesh

Sympatric and similar body-sized species exhibit interspecific competition for resources.  The present study investigated diel activity of five meso-carnivore species (Canis aureus, Felis chaus, Paradoxurus hermaphroditus, Viverricula indica, and Herpestes edwardsii) in a human-dominated region of Auroville and around Pondicherry University using camera-trap survey data.  Diel activity pattern and overlap were estimated using the kernel density method.  The Jungle Cat Felis chaus and the Golden Jackal Canis aureus exhibited cathemeral diel activity with a high overlap between them (Δ̂1 = 0.78).  The Indian Grey Mongoose Herpestes edwardsii displayed a diurnal activity pattern and had low overlap with the Small Indian Civet Viverricula indica (Δ̂1 = 0.34).  Moderate overlap was found between the Small Indian Civet and the Palm Civet Paradoxurus hermaphroditus (Δ̂1 = 0.32).  Therefore, diel activity patterns of mesocarnivores indicate inter- and intra-specific trade-off competition avoidance resulting in successful foraging.  The present camera-trap survey has provided insights into diel activity patterns and more attention is required to be paid to the study of feeding and breeding ecology of these species in human-dominated landscapes. 


1976 ◽  
Vol 54 (9) ◽  
pp. 1481-1487 ◽  
Author(s):  
P. A. Anderson ◽  
J. W. Nowosielski ◽  
N. A. Croll

The emergence pattern of cercariae of Trichobilharzia ocellata from Lymnaea stagnalis was examined at 2-h intervals from infected snails acclimatized to 12 h light – 12 h dark periods. A marked diel pattern of emergence was found during the periods of illumination; this was reversed when the light–dark regime was reversed.A method for the continuous recording of the locomotory activity of L. stagnalis is described. Snails acclimatized to either normal or reversed dark–light regimes showed a consistent diel pattern of activity during illumination. Peak activity occurred in the first few hours of illumination.It is proposed that the diel activity pattern results from an internal rhythm in which the snail becomes entrained to the lighting regime. The close association between the diel activity pattern of the snail and the emergence of T. ocellata indicates that host movement stimulates cercarial emergence. Light is thought to influence the cercariae directly and indirectly through the snail.


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