Cowards or clever guys: an alternative nest defence strategy employed by shrikes against magpies

2021 ◽  
Author(s):  
Petr Veselý ◽  
Michaela Syrová ◽  
Michaela Voháňková ◽  
Jan Havlíček ◽  
Jana Nácarová ◽  
...  
Keyword(s):  
Nest Defence ◽  
Defence Strategy

Serbia and Croatia

2018 ◽  
Author(s):  
Filip Ejdus
Keyword(s):  
Foreign Policy ◽  
Cold War ◽  
Democratic Transition ◽  
Armed Forces ◽  
Small States ◽  
Foreign Policies ◽  
Defence Strategy ◽  
The Creation ◽  
The Cold War ◽  
National Defence

During the cold war, the Socialist Federative Republic of Yugoslavia was a middle-sized power pursuing a non-aligned foreign policy and a defence strategy based on massive armed forces, obligatory conscription, and a doctrine of ‘Total National Defence’. The violent disintegration of Yugoslavia in the early 1990s resulted in the creation of several small states. Ever since, their defence policies and armed forces have been undergoing a thorough transformation. This chapter provides an analysis of the defence transformation of the two biggest post-Yugoslav states—Serbia and Croatia—since the end of the cold war. During the 1990s, defence transformation in both states was shaped by the undemocratic nature of their regimes and war. Ever since they started democratic transition in 2000, and in spite of their diverging foreign policies, both states have pivoted towards building modern, professional, interoperable, and democratically controlled armed forces capable of tackling both traditional and emerging threats.

scholarly journals SEISMIC HAZARD IN TUSCANY: WHICH BEST DEFENCE STRATEGY?

2012 ◽  
Vol 3 (1) ◽  
pp. 45
Author(s):  
E. Mantovani ◽  
M. Viti ◽  
D. Babbucci ◽  
C. Tamburelli ◽  
N. Cenni ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Defence Strategy

scholarly journals Crying wolf to a predator: deceptive vocal mimicry by a bird protecting young

2015 ◽  
Vol 282 (1809) ◽  
pp. 20150798 ◽  
Author(s):  
Branislav Igic ◽  
Jessica McLachlan ◽  
Inkeri Lehtinen ◽  
Robert D. Magrath
Keyword(s):  
Indirect Effects ◽  
Trophic Levels ◽  
Alarm Calls ◽  
Toxic Species ◽  
Vocal Mimicry ◽  
Primary Nest ◽  
Defence Strategy ◽  
Multiple Species ◽  
Defensive Mimicry ◽  
As If

Animals often mimic dangerous or toxic species to deter predators; however, mimicry of such species may not always be possible and mimicry of benign species seems unlikely to confer anti-predator benefits. We reveal a system in which a bird mimics the alarm calls of harmless species to fool a predator 40 times its size and protect its offspring against attack. Our experiments revealed that brown thornbills ( Acanthiza pusilla ) mimic a chorus of other species' aerial alarm calls, a cue of an Accipiter hawk in flight, when predators attack their nest. The absence of any flying predators in this context implies that these alarms convey deceptive information about the type of danger present. Experiments on the primary nest predators of thornbills, pied currawongs ( Strepera graculina ), revealed that the predators treat these alarms as if they themselves are threatened by flying hawks, either by scanning the sky for danger or fleeing, confirming a deceptive function. In turn, these distractions delay attack and provide thornbill nestlings with an opportunity to escape. This sophisticated defence strategy exploits the complex web of interactions among multiple species across several trophic levels, and in particular exploits a predator's ability to eavesdrop on and respond appropriately to heterospecific alarm calls. Our findings demonstrate that prey can fool predators by deceptively mimicking alarm calls of harmless species, suggesting that defensive mimicry could be more widespread because of indirect effects on predators within a web of eavesdropping.

Influence of experimentally elevated testosterone on nest defence in dark-eyed juncos

1998 ◽  
Vol 56 (3) ◽  
pp. 617-621 ◽  
Author(s):  
J.MICHELLE CAWTHORN ◽  
DANA L MORRIS ◽  
ELLEN D KETTERSON ◽  
VAL NOLAN
Keyword(s):  
Nest Defence

scholarly journals Increased responsiveness in feeding behaviour of Caenorhabditis elegans after experimental coevolution with its microparasite Bacillus thuringiensis

2011 ◽  
Vol 8 (2) ◽  
pp. 234-236 ◽  
Author(s):  
Rebecca D. Schulte ◽  
Barbara Hasert ◽  
Carsten Makus ◽  
Nico K. Michiels ◽  
Hinrich Schulenburg
Keyword(s):  
Caenorhabditis Elegans ◽  
Bacillus Thuringiensis ◽  
Feeding Activity ◽  
Free Food ◽  
Immune System Activation ◽  
Evolution Experiment ◽  
Food Conditions ◽  
System Activation ◽  
Defence Strategy ◽  
Host Parasite

Immune responses, either constitutive or induced, are costly. An alternative defence strategy may be based on behavioural responses. For example, avoidance behaviour reduces contact with pathogens and thus the risk of infection as well as the requirement of immune system activation. Similarly, if pathogens are taken up orally, preferential feeding of pathogen-free food may be advantageous. Behavioural defences have been found in many animals, including the nematode Caenorhabditis elegans . We here tested nematodes from a laboratory based evolution experiment which had either coevolved with their microparasite Bacillus thuringiensis (BT) or evolved under control conditions. After 48 generations, coevolved populations were more sensitive to food conditions: in comparison with the controls, they reduced feeding activity in the presence of pathogenic BT strains while at the same time increasing it in the presence of non-pathogenic strains. We conclude that host–parasite coevolution can drive changes in the behavioural responsiveness to bacterial microbes, potentially leading to an increased defence against pathogens.

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