Feeding of House Wren Nestlings Afflicted by Hematophagous Ectoparasites: A Test of the Parental Compensation Hypothesis

Morrison, Brian L.; Johnson, L. Scott

doi:10.1093/condor/104.1.183

Cited by 9 publications

(5 citation statements)

References 19 publications

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“…Parasitized swallows and bluebirds did not effectively recover hemoglobin to nonparasitized levels, as found in other studies (Knutie et al, 2016;Morrison & Johnson, 2002;Råberg et al, 2007) (Table 3, Figure 3). Measuring micronuclei in red blood cells in the future would provide a proxy of whether any blood was recovered by the host .…”

Section: Discussionsupporting

confidence: 79%

“…Resistance mechanisms, such as mounting an immune response, can kill the parasite and therefore reduce the costs associated with parasite exposure, such as blood loss (Owen et al, 2010). Tolerance mechanisms, such as resource compensation or tissue repair, do not kill the parasite but instead allow the host to deal with greater parasite pressure (Christe, Richner, & Oppliger, 1996;Knutie et al, 2016;Medzhitov et al, 2012;Morrison & Johnson, 2002;Tripet & Richner, 1997).…”

Section: Introductionmentioning

confidence: 99%

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Host tolerance and resistance to parasitic nest flies differs between two wild bird species

Grab

Hiller

Hurlbert

et al. 2019

Ecology and Evolution

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Hosts have developed and evolved defense strategies to limit parasite damage. Hosts can reduce the damage that parasites cause by decreasing parasite fitness (resistance) or without affecting parasite fitness (tolerance). Because a parasite species can infect multiple host species, determining the effect of the parasite on these hosts and identifying host defense strategies can have important implications for multi‐host–parasite dynamics. Over 2 years, we experimentally manipulated parasitic flies (Protocalliphora sialia) in the nests of tree swallows (Tachycineta bicolor) and eastern bluebirds (Sialia sialis). We then determined the effects of the parasites on the survival of nestlings and compared defense strategies between host species. We compared resistance between host species by quantifying parasite densities (number of parasites per gram of host) and measured nestling antibody levels as a mechanism of resistance. We quantified tolerance by determining the relationship between parasite density and nestling survival and blood loss by measuring hemoglobin levels (as a proxy of blood recovery) and nestling provisioning rates (as a proxy of parental compensation for resources lost to the parasite) as potential mechanisms of tolerance. For bluebirds, parasite density was twice as high as for swallows. Both host species were tolerant to the effects of P. sialia on nestling survival at their respective parasite loads but neither species were tolerant to the blood loss to the parasite. However, swallows were more resistant to P. sialia compared to bluebirds, which was likely related to the higher antibody‐mediated immune response in swallow nestlings. Neither blood recovery nor parental compensation were mechanisms of tolerance. Overall, these results suggest that bluebirds and swallows are both tolerant of their respective parasite loads but swallows are more resistant to the parasites. These results demonstrate that different host species have evolved similar and different defenses against the same species of parasite.

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Section: Discussionsupporting

confidence: 79%

Section: Introductionmentioning

confidence: 99%

Host tolerance and resistance to parasitic nest flies differs between two wild bird species

Grab

Hiller

Hurlbert

et al. 2019

Ecology and Evolution

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“…Studies on similar systems in North America involving hematophagous larvae of Protocalliphora spp. also failed to show a significant difference in parental food provisioning in relation to infestation, as for example, Eastern Bluebirds ( Sialia sialis ) infested by the blowfly Protocalliphora sialia (Grab et al 2019 ), or House Wrens ( Troglodytes aedon ) infested by Protocalliphora parorum (Morrison and Johnson 2002 ).…”

Section: Discussionmentioning

confidence: 99%

“…However, parental compensation via a higher food supply to nestlings, or other behaviors, will increase current reproductive effort, but at the expense of reducing residual reproductive value (Perrin et al 1996 ), a life-history trade-off experimentally demonstrated in many studies (e.g., Richner and Tripet 1999 ). Higher food provisioning allows nestlings to allocate more resources to blood and tissue replacement and growth (Mason 1944 ; Johnson and Albrecht 1993 ; Morrison and Johnson 2002 ). The extent of parental compensation may be influenced by environmental conditions and the amount or quality of available food (Tremblay et al 2005 ), among other factors.…”

Section: Introductionmentioning

confidence: 99%

Parental food provisioning and nestling growth under Philornis downsi parasitism in the Galapagos Green Warbler-Finch, classified as ‘vulnerable’ by the IUCN

et al. 2023

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In the Galapagos Islands, many endemic landbird populations are declining due to habitat degradation, food availability, introduced species and other factors. Given nestlings typically lack efficient defense mechanisms against parasites, hematophagous ectoparasites such as the larvae of the introduced Avian Vampire Fly, Philornis downsi, can impose high brood mortality and cause threatening population declines in Darwin finches and other landbirds. Here, we assess whether the food compensation hypothesis (i.e., the parents’ potential to compensate for deleterious parasite effects via increased food provisioning) applies to the Green Warbler-Finch. We differentiated nests with low or high infestation levels by P. downsi and quantified food provisioning rates of male and female parents, time females spent brooding nestlings, and nestling growth. Male provisioning rates, total provisioning rates and female brooding time did not significantly vary in relation to infestation levels, nor by the number of nestlings. Opposed to the predictions of the food compensation hypothesis, females showed significantly reduced provisioning rates at high infestation levels. Nestling body mass was significantly lower and there was a reduction of skeletal growth, although not significantly, in highly infested nests. The females’ response to high infestation may be due to parasites directly attacking and weakening brooding females, or else that females actively reduce current reproductive effort in favor of future reproduction. This life-history trade-off may be typical for Darwin finches and many tropical birds with long lifespans and therefore high residual reproductive value. Conservation strategies may not build on the potential for parental food compensation by this species.

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“…Most studies on host parental care in response to ectoparasites have tested the food compensation hypothesis, which predicts that parents will increase food delivery to offspring at parasitized nests to compensate for the nutritional and energetic costs of parasitism [15,16]. Evidence for the food compensation hypothesis has been mixed [17][18][19][20][21], perhaps due to sex differences in the value of current versus future broods [20].…”

Section: Introductionmentioning

confidence: 99%

Female in-nest attendance predicts the number of ectoparasites in Darwin's finch species

Kleindorfer

Common

O’Connor³

et al. 2021

Proc. R. Soc. B.

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Selection should act on parental care and favour parental investment decisions that optimize the number of offspring produced. Such predictions have been robustly tested in predation risk contexts, but less is known about alternative functions of parental care under conditions of parasitism. The avian vampire fly ( Philornis downsi ) is a myasis-causing ectoparasite accidentally introduced to the Galápagos Islands, and one of the major mortality causes in Darwin's finch nests. With an 11-year dataset spanning 21 years, we examine the relationship between parental care behaviours and number of fly larvae and pupae in Darwin's finch nests. We do so across three host species ( Camarhynchus parvulus , C. pauper , Geospiza fuliginosa ) and one hybrid Camarhynchus group. Nests with longer female brooding duration (minutes per hour spent sitting on hatchlings to provide warmth) had fewer parasites, and this effect depended on male food delivery to chicks. Neither male age nor number of nest provisioning visits were directly associated with number of parasites. While the causal mechanisms remain unknown, we provide the first empirical study showing that female brooding duration is negatively related to the number of ectoparasites in nests. We predict selection for coordinated host male and female behaviour to reduce gaps in nest attendance, especially under conditions of novel and introduced ectoparasites.

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Feeding of House Wren Nestlings Afflicted by Hematophagous Ectoparasites: A Test of the Parental Compensation Hypothesis

Cited by 9 publications

References 19 publications

Host tolerance and resistance to parasitic nest flies differs between two wild bird species

Host tolerance and resistance to parasitic nest flies differs between two wild bird species

Parental food provisioning and nestling growth under Philornis downsi parasitism in the Galapagos Green Warbler-Finch, classified as ‘vulnerable’ by the IUCN

Female in-nest attendance predicts the number of ectoparasites in Darwin's finch species

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