科创中国

Lesser kestrels Falco naumanni are migratory central-place foragers that breed in dynamic arable landscapes. After arriving from migration, kestrels have no knowledge of the distribution of crops, and consequently prey, around their colony. The energy demand of pairs increases as breeding season progresses, but at the same time prey abundance, and their knowledge on prey distribution, also increases. Wind can have a strong influence on flight cost and kestrels should try to reduce energy expendi- ture when possible. When prey abundance is low, kestrels have little knowledge of prey distribution, and pairs have no chicks, they could reduce foraging flight cost by leaving the colony with tailwinds. When prey is abundant, knowledge on prey distribu- tion has increased, and chick demand is high, kestrels should fly to the most favorable foraging patches. We analyzed foraging trips directions in a lesser kestrel colony along the breeding season and in relation to wind speed and direction. We recorded 664 foraging trips from 19 individuals using GPS-dataloggers. We found that outward flights direction changed from uniform to a concentrated distribution along the season, as prey abundance and individual experience increased. We also found a temporal trend in the angular difference between outward flights and wind directions, with low values early in the season and then increa- sing as expected, but again low values at the end, contrary to expectation. Results suggest changes in kestrels foraging strategy along the season in relation to wind. Kestrels depart more with tailwinds in exploratory flights early in the season, while there is a spurious coincidence in direction to preferred foraging patches and dominant wind direction at the end [Current Zoology 60 (5): 604-615, 2014].

Because antipredator behaviours are costly, the threat-sensitive predator avoidance hypothesis predicts that individual animals should express predator-avoidance behaviour proportionally to the perceived threat posed by the predator. Here, we experimentally tested this hypothesis by providing wild passerine birds supplemental food (on a raised feeding platform) at either 1 or 4 m from the edge of forest cover (potential refuge), in either the presence or absence of a nearby simulated predation threat (a sharp-shinned hawk Accipiter striatus model). Compared with the control treatment, we observed proportionally fewer bird visits to the food patch, and the birds took longer to re-emerge from forest refuge and return to feed at the food patch, after the hawk presentation than before it. The observed threat-sensitive latency-to-return response was stronger when the food patch was further away from the nearest refuge. Overall, our results are consistent with the predictions of the threat-sensitive predator avoidance hypothesis in that wild passerine birds (primarily black-capped chickadees Poecile atricapillus) exhibited more intense antipre- dator behavioural responses with increasing level of apparent threat. The birds were thus sensitive to their local perceived threat of predation and traded-off safety from predation (by refuging) and foraging gains in open habitat in a graded, threat-sensitive manner [Current Zoology 60 (6): 719-728, 2014].

Recursion?by?herbivores?is?the?repeated?use?of?the?same?site?or?plants.?Recursion?by?wild?animals?is?rarely?investigated?but?may?be?ubiquitous.?Optimal?foraging?theory?predicts?site?recursion?as?a?function?of?the?quality?of?the?site,?extent?of?its?last?use,?and?time?since?its?last?use?because?these?influence?site?resource?status?and?recovery.?We?used?GPS?collars,?behaviour?and?site?sampling?to?investigate?recursion?to?foraging?sites?for?two?elephant?Elephas?maximus?borneensis?herds?in?the?Lower?Kinabatangan?Wildlife?Sanctuary,?Borneo,?over?a?12?month?period.?Recursion?occurred?to?48?out?of?87?foraging?sites?and?was?most?common?within?48?hours?or?between?151-250?days,?indicating?two?different?types?ofrecursion.?Recursion?was?more?likely?to?occur?if?the?site?had?previously?been?occupied?for?longer.?Moreover,?the?time?spent?at?a?site?at?recursion?was?the?same?as?the?time?spent?at?the?site?on?the?first?occasion.?The?number?of?days?that?had?passed?between?the?first?visit?and?recursion?was?also?positively?correlated?with?how?much?time?was?spent?at?the?site?at?recursion.?Habitat?type?also?influenced?the?intensity?of?site-use,?with?more?time?spent?at?recursion?within?riverine/open?grass?areas?along?forest?margins?compared?to?other?habitat?types.?Recursion?is?a?common?behaviour?used?by?the?elephants?and?its?pattern?suggests?it?may?be?a?foraging?strategy?for?revisiting?areas?of?greater?value.?The?qualities?of?recursion?sites?might?usefully?be?incorporated?into?landscape?management?strategies?for?elephant?conservation?in?the?area?[Current?Zoology?60?(4):?551-559,?2014].