Rapid change in host use of the common cuckooCuculus canoruslinked to climate change

Abstract

Parasites require synchrony with their hosts so if host timing changes with climate change, some parasites may decline and eventually go extinct. Residents and short-distance migrant hosts of the brood parasitic common cuckoo, Cuculus canorus, have advanced their phenology in response to climate change more than long-distance migrants, including the cuckoo itself. Because different parts of Europe show different degrees of climate change, we predicted that use of residents or short-distance migrants as hosts should have declined in areas with greater increase in spring temperature. Comparing relative frequency of parasitism of the two host categories in 23 European countries before and after 1990, when spring temperatures in many areas had started to increase, we found that relative parasitism of residents and short-distance migrants decreased. This change in host use was positively related to increase in spring temperature, consistent with the prediction that relative change in phenology for different migrant classes drives host-use patterns. These findings are consistent with the hypothesis that climate change affects the relative abundance of different host races of the common cuckoo.

Has climate change resulted in a mismatch between the spring arrival of the Common Cuckoo Cuculus canorus and its hosts in North Norway?

“…Earlier studies have suggested that a more rapid advance in arrival dates and the implicit advance in the initiation of breeding of short-distance migrant hosts in response to increases in temperature than that of the cuckoo may result in a decrease in availability of host nests and thus contribute to the population decline of the latter (Saino et al 2009, Møller et al 2011, Balmer et al 2013). This study, however, documents a significant advance of arrival dates of the cuckoo to North Norway over a 30 year period, with an acceleration since 1997 but not so of its main host the meadow pipit.…”

“…The arrival of the brambling, on the other hand, has advanced at over twice the rate (1.8 d yr -1 ) of that of the cuckoo since the late 1990s. Unless the brambling is (or has become -see Møller et al 2011) a more important host for the cuckoo in North Norway than in the rest of the country, there is thus no evidence of a progressive negative phenological mismatch between the cuckoo and its hosts that may contribute to a decline in the Norwegian population of the former. One explanation may be that the implicit relationship between arrival date and laying date does not exist, as recently postulated by Dunn & Møller (2014).…”

“…Causes of this decline are unclear and may be related to resource availability in the cuckoos' wintering quarters, along their migration routes and/or in the breeding area, or to declines in the abundance of their hosts (Douglas et al 2010, Erritzøe & Mann 2012. There is also evidence to show that climate change might be disrupting the close association between the migration and breeding phenology of the cuckoo and its hosts resulting in a mismatch in their respective nesting times (Saino et al 2009, Møller et al 2011. Whereas the cuckoo, itself a longdistance migrant wintering south of the Sahara in Africa, seems to be keeping track of the phenology of other long-distance, migratory hosts, this mismatch is especially evident between the cuckoo and its short-distance migrant hosts that winter in Europe or North Africa (Saino et al 2009).…”

A siblicidal origin for avian brood parasitism?

“…Variation in these same factors, exhibited by both parasite and host, have also been shown to influence the arms race between parasite strategy and host defense (Hoover and Hauber 2007;Saino et al 2009;Møller et al 2011). Natal philopatry in hosts may lead to the intergenerational transmission of parasitic egg acceptance; among Prothonotary Warblers Protonotaria citrea, daughters raised in nests with parasites were more philopatric and likely to be parasitized themselves than their counterparts raised without parasites (Hoover and Hauber 2007).…”

“…The reuse of nests within a season provides brood parasites multiple opportunities to parasitize a known location; some species of brood parasites have, in turn, evolved strategies to manipulate renesting behaviour of hosts, such as 'mafia' and 'farming' tactics (Hoover and Robinson 2007;Hauber 2009). Changes in climate have been shown to impact the timing of parasitic behaviour relative to host laying, as populations of hosts move or expand their range (Saino et al 2009;Møller et al 2011). Brood parasites may be effective invaders due to their ability to lay eggs far from their own feeding sites, adding another layer of feedback from migratory habits (Krüger and Davies 2002).…”