The effect of food supplementation on the reproductive success of Black-billed Magpies Pica pica

Ibis ◽  
2008 ◽  
Vol 132 (4) ◽  
pp. 595-602 ◽  
Author(s):  
MANJIT S. DHINDSA ◽  
DAVID A. BOAG
2015 ◽  
Vol 282 (1812) ◽  
pp. 20150762 ◽  
Author(s):  
Simone Vincenzi ◽  
Scott Hatch ◽  
Thomas Merkling ◽  
Alexander S. Kitaysky

Supplementation of food to wild animals is extensively applied as a conservation tool to increase local production of young. However, in long-lived migratory animals, the carry-over effects of food supplementation early in life on the subsequent recruitment of individuals into natal populations and their lifetime reproductive success are largely unknown. We examine how experimental food supplementation early in life affects: (i) recruitment as breeders of kittiwakes Rissa tridactyla born in a colony on Middleton Island (Alaska) between 1996 and 2006 ( n = 1629) that bred in the same colony through 2013 ( n = 235); and (ii) breeding success of individuals that have completed their life cycle at the colony ( n = 56). Birds were raised in nests that were either supplemented with food (Fed) or unsupplemented (Unfed). Fledging success was higher in Fed compared with Unfed nests. After accounting for hatching rank, growth and oceanic conditions at fledging, Fed fledglings had a lower probability of recruiting as breeders in the Middleton colony than Unfed birds. The per-nest contribution of breeders was still significantly higher for Fed nests because of their higher productivity. Lifetime reproductive success of a subset of kittiwakes that thus far had completed their life cycle was not affected by the food supplementation during development. Our results cast light on the carry-over effects of early food conditions on the vital rates of long-lived animals and support food supplementation as an effective conservation strategy for long-lived seabirds.


1987 ◽  
Vol 65 (5) ◽  
pp. 1270-1274 ◽  
Author(s):  
Wesley M. Hochachka ◽  
David A. Boag

Supplemental food was provided to a breeding population of Black-billed Magpies (Pica pica), starting before and after eggs were laid, to determine if and when natural food was limited. The production of fledgling magpies was increased only when supplemental feeding was begun before laying. Laying date was also advanced when supplemental feeding began before laying, but clutch and egg size were not significantly changed. Because the two feeding treatments were conducted in different years, we cannot conclude whether natural food was limiting before or after egg laying. However, out data suggest that the former may have been the case. An improved design for food supplementation experiments, which can be used to determine the time of food shortage, is suggested.


The Condor ◽  
2001 ◽  
Vol 103 (4) ◽  
pp. 870-874 ◽  
Author(s):  
Michael S. Rodway ◽  
Fred Cooke

Abstract We investigated three types of decisions made by Harlequin Ducks (Histrionicus histrionicus) in moving between nearshore feeding and offshore resting areas: when to move, whether to move synchronously, and whether to form dense flocks on the roosting grounds. We used the spawning of Pacific herring (Clupea pallasi) as a natural food-supplementation experiment. Birds arrived at nearshore feeding areas a few minutes later and departed almost an hour earlier relative to sunrise and sunset when spawn was available than before and after. Cloud cover and high winds resulted in earlier departures, especially during spawning. Arriving, departing, and offshore groups consisted most frequently of two ducks, and birds showed little tendency to synchronize movements or to form dense flocks when resting. Results indicate that Harlequin Ducks avoid crepuscular and nocturnal periods near shore when not constrained by food availability and the length of daylight in which to feed. Efecto de la Disponibilidad de Alimento en las Decisiones de Arribo y Partida de Histrionicus histrionicus en Áreas de Alimentación Diurna Resumen. Investigamos tres tipos de decisiones hechas por Histrionicus histrionicus (Pato Arlequín) al moverse entre áreas de alimentación cercanas a la costa y áreas de reposo mar adentro: cuándo moverse, si se mueven de modo sincrónico, y si forman bandadas densas en las áreas de reposo. Utilizamos el desove del arenque del Pacífico (Clupea pallasi) como un experimento de suplemento de alimento natural. En relación al amanecer y anochecer, las aves llegaron a las áreas de alimentación cercanas a la costa unos minutos después y se fueron casi una hora más temprano cuando los huevos de peces estuvieron disponibles que cuando no lo estuvieron, ya sea antes o después. Cobertura de nubes y fuertes vientos trajeron aparejadas partidas más tempranas, especialmente durante la etapa de desove. Los grupos que llegaban, partían y los que se encontraban mar adentro estuvieron en su mayoría conformados por dos patos, y las aves en general no tendieron a sincronizar sus movimientos o a formar grupos densos durante el reposo. Los resultados indican que H. histrionicus evita permanecer cerca de la costa durante períodos crepusculares y nocturnos cuando no se haya limitado por la disponibilidad de alimentos y por la cantidad de horas de luz para alimentarse.


1976 ◽  
Vol 31 (5) ◽  
pp. 384-388 ◽  
Author(s):  
AARON LECHTIG ◽  
JEAN-PIERRE HABICHT ◽  
HERNAN DELGADO ◽  
ROBERT E. KLEIN ◽  
CHARLES YARBROUGH ◽  
...  

2019 ◽  
Author(s):  
Sarah A. Knutie

AbstractSupplemental feeding can increase the overall health of animals but also can have varying consequences for animals dealing with parasites. Furthermore, the mechanism mediating the effect of food supplementation on host-parasite interactions remains poorly understood.The goal of the study was to determine the effect of food supplementation on host defenses against parasitic nest flies and whether host gut microbiota, which can affect immunity, potentially mediates these relationships. In a fully crossed design, I experimentally manipulated the abundance of parasitic nest flies (Protocalliphora sialia) and food availability then characterized the gut microbiota, immune responses, and nest parasite abundance of nestling eastern bluebirds (Sialia sialis).Food supplemented birds had 75% fewer parasites than unsupplemented birds. Parasite abundance decreased throughout the breeding season for unsupplemented birds, but abundance did not change throughout the season for supplemented birds. Food supplementation increased overall fledging success. Parasitism had a sublethal effects on blood loss, but food supplementation mitigated these effects by increasing parasite resistance via the nestling IgY antibody response.Food supplementation increased the gut bacterial diversity in nestlings, which was negatively related to parasite abundance. Food supplementation also increased the relative abundance of Clostridium spp. in nestlings, which was positively related to their antibody response and negatively related to parasite abundance.Synthesis and applications. Overall, these results suggest that food supplementation, especially early in the breeding season, increases resistance to parasitism during the early life stage of the host, which could be mediated by the effect of supplementation on the gut microbiota. Wildlife food supplementation is a common pastime for humans worldwide and therefore it is important to determine the consequences of this activity on animal health. Furthermore, supplemental feeding could induce resistance to detrimental parasites (e.g. invasive parasites) in hosts when management of the parasite is not immediately possible.


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