Facultative adjustment of pre-fledging mass recession by nestling chimney swifts Chaetura pelagica

2014 ◽  
Vol 45 (3) ◽  
pp. 247-252 ◽  
Author(s):  
Sagan Goodpaster ◽  
Gary Ritchison
2005 ◽  
Vol 83 (11) ◽  
pp. 1476-1485 ◽  
Author(s):  
Makiko Takenaka ◽  
Yasuaki Niizuma ◽  
Yutaka Watanuki

By manipulating meal size and frequency in an alcid, the rhinoceros auklet (Cerorhinca monocerata (Pallas, 1811)), we examined two hypotheses: (1) poorly fed chicks allocate resources preferentially to developing organs essential for fledging, and (2) intermittently fed chicks deposit more lipids than regularly fed ones. Chicks were fed normal (NORMAL; 40–80 g, mean meal mass in a normal year), small (LOW; 26–54 g, half of NORMAL), or large (HIGH; 80–160 g, twice as much as NORMAL) amounts of sandlance (Ammodytes personatus Girard, 1856) every day or the large meal (80–160 g) every 2 days (INTERMITTENT). Chicks fed more food grew faster. The HIGH group had the greatest fledging mass and shortest fledging period. The wingspan and brain mass of fledglings did not differ among groups. The heart, liver, and breast muscle at fledging were 15%–25% smaller in the LOW group than in the NORMAL group but did not differ between the NORMAL and HIGH groups. The total lipid was 43% greater in the HIGH group than in the NORMAL group, and that of the LOW group was 38% smaller. The INTERMITTENT group had a similar lipid mass to the NORMAL group. Chicks feeding on small meals seemed to maintain the growth of organs essential for fledging, while chicks feeding on large meals seemed to deposit a surplus as lipid rather than allocate more to the development of organs.


2020 ◽  
Vol 47 (6) ◽  
pp. 468
Author(s):  
Gemma Bell ◽  
Melanie J. Young ◽  
Philip J. Seddon ◽  
Yolanda van Heezik

Abstract Context Wildlife tourism is expanding and can detrimentally affect taxa such as penguins, if not managed carefully. The yellow-eyed penguin (Megadyptes antipodes) is an endangered species, with mainland populations projected to decline to extinction in the next 40 years, despite conservation interventions. Their nesting sites are exposed to increasing numbers of human visitors, which contributes to reduced reproductive success. AimsWe evaluated the effectiveness of a breeding colony (Boulder Beach) closure to the public, which was implemented to reduce visitor disturbance. MethodsWe compared reproductive success 5 years before and 5 years during the closure with success at an adjacent site (Sandfly Bay) that experiences high human disturbance, over the same time periods. Key resultsBeach closure did not result in an increase in chick mass or survival at Boulder Beach; however, trends at adjacent Sandfly Bay suggested that, without the closure, chick survival at Boulder Beach would likely have declined. Chick survival decreased at Sandfly Bay across the two 5-year periods, whereas chick survival at Boulder Beach did not decline, but remained constant during the closure years. ConclusionsThe beach closure was beneficial because it appeared to buffer environmental factors, so that mean chick survival remained constant rather than declining. Implications Beach closures might be difficult to implement because of public expectations regarding free access to coastal land in New Zealand, but they should be considered at sites where increasing numbers of visitors are likely to have detrimental impacts on wildlife. Without urgent action, these culturally important animals will likely be extinct on mainland New Zealand within the next few decades. Beach closures may represent an effective management measure to increase population resilience by decreasing the detrimental impacts of visitors on breeding success.


The Auk ◽  
2001 ◽  
Vol 118 (4) ◽  
pp. 944-957 ◽  
Author(s):  
Hans Schekkerman ◽  
G. Henk Visser ◽  
C. Blem

Abstract Understanding ecological consequences of avian developmental modes requires knowledge of energy requirements of chicks of different positions in the precocial–altricial spectrum, but those have rarely been measured in birds with self-feeding precocial young. We studied prefledging energy budgets in chicks of Black-tailed Godwit (Limosa limosa) and Northern Lapwing (Vanellus vanellus) in the field and in the laboratory. Lapwings show slower growth than godwits, reaching a 29% lower fledging mass (142 vs. 201 g) in a 32% longer period (33 vs. 25 days). Daily energy expenditure (DEE), measured by the doubly labelled water (DLW) technique, and daily metabolized energy (DEE plus energy deposited into tissue) increased proportionally to body mass at similar levels in both species. Total metabolized energy (TME) over the fledging period was 8,331 kJ in godwits and 6,982 kJ in lapwings, 39 and 29% higher than an allometric prediction (Weathers 1992). That suggests that self-feeding precocial chicks have high energy requirements compared with parent-fed species, due to costs of activity and thermoregulation associated with foraging. Those components made up 50–53% of TME in the shorebirds, more than twice as much as in seven parent-fed species for which DLW-based energy budgets are available. In captive lapwings and godwits growing up under favorable thermal conditions with food readily accessible, thermoregulation and activity costs were 53–58% lower and TME was 26–31% lower than in free-living chicks. The proportion of TME allocated to tissue formation (13–15% deposited as tissue plus 10–12% synthesis costs) was low in the shorebirds, and reductions in food intake may therefore sooner lead to stagnation of growth than in parent-fed chicks. Furthermore, the need to forage limits potential for saving energy by reducing activity in periods of food scarcity, because that will further decrease food intake. Self-feeding precocial chicks thus seem to operate within fairly narrow energetic margins. At the same time, self-feeding may allow birds to use food types that could not be profitably harvested if they had to be transported to the young.


2014 ◽  
Author(s):  
Tanner K. Steeves ◽  
Shannon B. Kearney-McGee ◽  
Margaret A. Rubega ◽  
Calvin L. Cink ◽  
Charles T. Collins
Keyword(s):  

2020 ◽  
Author(s):  
Tanner K. Steeves ◽  
Shannon B. Kearney-McGee ◽  
Margaret A. Rubega ◽  
Calvin L. Cink ◽  
Charles T. Collins
Keyword(s):  

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